Class CharBuffer
- All Implemented Interfaces:
Appendable,CharSequence,Comparable<CharBuffer>,Readable
This class defines four categories of operations upon char buffers:
Absolute and relative
getandputmethods that read and write single chars;Absolute and relative
bulk getmethods that transfer contiguous sequences of chars from this buffer into an array;Absolute and relative
bulk putmethods that transfer contiguous sequences of chars from a char array, a string, or some other char buffer into this buffer;A method for
compactinga char buffer.
Char buffers can be created either by allocation, which allocates space for the buffer's
content, by wrapping an existing
char array or string into a buffer, or by creating a
view of an existing byte buffer.
Like a byte buffer, a char buffer is either direct or non-direct. A
char buffer created via the wrap methods of this class will
be non-direct. A char buffer created as a view of a byte buffer will
be direct if, and only if, the byte buffer itself is direct. Whether or not
a char buffer is direct may be determined by invoking the isDirect method.
This class implements the CharSequence interface so that
character buffers may be used wherever character sequences are accepted, for
example in the regular-expression package java.util.regex.
The methods defined by CharSequence operate relative to the current
position of the buffer when they are invoked.
Methods in this class that do not otherwise have a value to return are specified to return the buffer upon which they are invoked. This allows method invocations to be chained. The sequence of statements
cb.put("text/");
cb.put(subtype);
cb.put("; charset=");
cb.put(enc);
cb.put("text/").put(subtype).put("; charset=").put(enc);
Optional operations
Methods specified as optional operations throw a ReadOnlyBufferException when invoked on a read-only CharBuffer. The methods array and arrayOffset throw an UnsupportedOperationException if the CharBuffer is not backed by an accessible char array (irrespective of whether the CharBuffer is read-only).- Since:
- 1.4
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Method Summary
Modifier and TypeMethodDescriptionstatic CharBufferallocate(int capacity) Allocates a new char buffer.append(char c) Appends the specified char to this buffer (optional operation).append(CharSequence csq) Appends the specified character sequence to this buffer (optional operation).append(CharSequence csq, int start, int end) Appends a subsequence of the specified character sequence to this buffer (optional operation).final char[]array()Returns the char array that backs this buffer (optional operation).final intReturns the offset within this buffer's backing array of the first element of the buffer (optional operation).abstract CharBufferCreates a new, read-only char buffer that shares this buffer's content.final charcharAt(int index) Reads the character at the given index relative to the current position.final CharBufferclear()Clears this buffer.abstract CharBuffercompact()Compacts this buffer (optional operation).intcompareTo(CharBuffer that) Compares this buffer to another.abstract CharBufferCreates a new char buffer that shares this buffer's content.booleanTells whether or not this buffer is equal to another object.final CharBufferflip()Flips this buffer.abstract charget()Relative get method.get(char[] dst) Relative bulk get method.get(char[] dst, int offset, int length) Relative bulk get method.abstract charget(int index) Absolute get method.get(int index, char[] dst) Absolute bulk get method.get(int index, char[] dst, int offset, int length) Absolute bulk get method.final booleanhasArray()Tells whether or not this buffer is backed by an accessible char array.inthashCode()Returns the current hash code of this buffer.abstract booleanisDirect()Tells whether or not this char buffer is direct.final booleanisEmpty()Returnstrueif this character buffer is empty.final intlength()Returns the length of this character buffer.final CharBufferlimit(int newLimit) Sets this buffer's limit.final CharBuffermark()Sets this buffer's mark at its position.intmismatch(CharBuffer that) Finds and returns the relative index of the first mismatch between this buffer and a given buffer.abstract ByteOrderorder()Retrieves this buffer's byte order.final CharBufferposition(int newPosition) Sets this buffer's position.abstract CharBufferput(char c) Relative put method (optional operation).final CharBufferput(char[] src) Relative bulk put method (optional operation).put(char[] src, int offset, int length) Relative bulk put method (optional operation).abstract CharBufferput(int index, char c) Absolute put method (optional operation).put(int index, char[] src) Absolute bulk put method (optional operation).put(int index, char[] src, int offset, int length) Absolute bulk put method (optional operation).put(int index, CharBuffer src, int offset, int length) Absolute bulk put method (optional operation).final CharBufferRelative bulk put method (optional operation).Relative bulk put method (optional operation).put(CharBuffer src) Relative bulk put method (optional operation).intread(CharBuffer target) Attempts to read characters into the specified character buffer.final CharBufferreset()Resets this buffer's position to the previously-marked position.final CharBufferrewind()Rewinds this buffer.abstract CharBufferslice()Creates a new char buffer whose content is a shared subsequence of this buffer's content.abstract CharBufferslice(int index, int length) Creates a new char buffer whose content is a shared subsequence of this buffer's content.abstract CharBuffersubSequence(int start, int end) Creates a new character buffer that represents the specified subsequence of this buffer, relative to the current position.toString()Returns a string containing the characters in this buffer.static CharBufferwrap(char[] array) Wraps a char array into a buffer.static CharBufferwrap(char[] array, int offset, int length) Wraps a char array into a buffer.static CharBufferwrap(CharSequence csq) Wraps a character sequence into a buffer.static CharBufferwrap(CharSequence csq, int start, int end) Wraps a character sequence into a buffer.Methods declared in class java.nio.Buffer
capacity, hasRemaining, isReadOnly, limit, position, remainingMethods declared in class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, waitMethods declared in interface java.lang.CharSequence
chars, codePoints
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Method Details
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allocate
Allocates a new char buffer.The new buffer's position will be zero, its limit will be its capacity, its mark will be undefined, each of its elements will be initialized to zero, and its byte order will be the
native orderof the underlying hardware. It will have abacking array, and itsarray offsetwill be zero.- Parameters:
capacity- The new buffer's capacity, in chars- Returns:
- The new char buffer
- Throws:
IllegalArgumentException- If thecapacityis a negative integer
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wrap
Wraps a char array into a buffer.The new buffer will be backed by the given char array; that is, modifications to the buffer will cause the array to be modified and vice versa. The new buffer's capacity will be
array.length, its position will beoffset, its limit will beoffset + length, its mark will be undefined, and its byte order will be thenative orderof the underlying hardware. Itsbacking arraywill be the given array, and itsarray offsetwill be zero.- Parameters:
array- The array that will back the new bufferoffset- The offset of the subarray to be used; must be non-negative and no larger thanarray.length. The new buffer's position will be set to this value.length- The length of the subarray to be used; must be non-negative and no larger thanarray.length - offset. The new buffer's limit will be set tooffset + length.- Returns:
- The new char buffer
- Throws:
IndexOutOfBoundsException- If the preconditions on theoffsetandlengthparameters do not hold
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wrap
Wraps a char array into a buffer.The new buffer will be backed by the given char array; that is, modifications to the buffer will cause the array to be modified and vice versa. The new buffer's capacity and limit will be
array.length, its position will be zero, its mark will be undefined, and its byte order will be thenative orderof the underlying hardware. Itsbacking arraywill be the given array, and itsarray offsetwill be zero.- Parameters:
array- The array that will back this buffer- Returns:
- The new char buffer
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read
Attempts to read characters into the specified character buffer. The buffer is used as a repository of characters as-is: the only changes made are the results of a put operation. No flipping or rewinding of the buffer is performed. If the length of the specified character buffer is zero, then no characters will be read and zero will be returned.- Specified by:
readin interfaceReadable- Parameters:
target- the buffer to read characters into- Returns:
- The number of characters added to the buffer, possibly zero, or -1 if this source of characters is at its end
- Throws:
IOException- if an I/O error occursReadOnlyBufferException- if target is a read only buffer, even if its length is zero- Since:
- 1.5
-
wrap
Wraps a character sequence into a buffer.The content of the new, read-only buffer will be the content of the given character sequence. The buffer's capacity will be
csq.length(), its position will bestart, its limit will beend, and its mark will be undefined.- Parameters:
csq- The character sequence from which the new character buffer is to be createdstart- The index of the first character to be used; must be non-negative and no larger thancsq.length(). The new buffer's position will be set to this value.end- The index of the character following the last character to be used; must be no smaller thanstartand no larger thancsq.length(). The new buffer's limit will be set to this value.- Returns:
- The new character buffer
- Throws:
IndexOutOfBoundsException- If the preconditions on thestartandendparameters do not hold
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wrap
Wraps a character sequence into a buffer.The content of the new, read-only buffer will be the content of the given character sequence. The new buffer's capacity and limit will be
csq.length(), its position will be zero, and its mark will be undefined.- Parameters:
csq- The character sequence from which the new character buffer is to be created- Returns:
- The new character buffer
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slice
Creates a new char buffer whose content is a shared subsequence of this buffer's content.The content of the new buffer will start at this buffer's current position. Changes to this buffer's content will be visible in the new buffer, and vice versa; the two buffers' position, limit, and mark values will be independent.
The new buffer's position will be zero, its capacity and its limit will be the number of chars remaining in this buffer, its mark will be undefined, and its byte order will be identical to that of this buffer. The new buffer will be direct if, and only if, this buffer is direct, and it will be read-only if, and only if, this buffer is read-only.
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slice
Creates a new char buffer whose content is a shared subsequence of this buffer's content.The content of the new buffer will start at position
indexin this buffer, and will containlengthelements. Changes to this buffer's content will be visible in the new buffer, and vice versa; the two buffers' position, limit, and mark values will be independent.The new buffer's position will be zero, its capacity and its limit will be
length, its mark will be undefined, and its byte order will be identical to that of this buffer. The new buffer will be direct if, and only if, this buffer is direct, and it will be read-only if, and only if, this buffer is read-only.- Specified by:
slicein classBuffer- Parameters:
index- The position in this buffer at which the content of the new buffer will start; must be non-negative and no larger thanlimit()length- The number of elements the new buffer will contain; must be non-negative and no larger thanlimit() - index- Returns:
- The new buffer
- Throws:
IndexOutOfBoundsException- Ifindexis negative or greater thanlimit(),lengthis negative, orlength > limit() - index- Since:
- 13
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duplicate
Creates a new char buffer that shares this buffer's content.The content of the new buffer will be that of this buffer. Changes to this buffer's content will be visible in the new buffer, and vice versa; the two buffers' position, limit, and mark values will be independent.
The new buffer's capacity, limit, position, mark values, and byte order will be identical to those of this buffer. The new buffer will be direct if, and only if, this buffer is direct, and it will be read-only if, and only if, this buffer is read-only.
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asReadOnlyBuffer
Creates a new, read-only char buffer that shares this buffer's content.The content of the new buffer will be that of this buffer. Changes to this buffer's content will be visible in the new buffer; the new buffer itself, however, will be read-only and will not allow the shared content to be modified. The two buffers' position, limit, and mark values will be independent.
The new buffer's capacity, limit, position, mark values, and byte order will be identical to those of this buffer.
If this buffer is itself read-only then this method behaves in exactly the same way as the
duplicatemethod.- Returns:
- The new, read-only char buffer
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get
public abstract char get()Relative get method. Reads the char at this buffer's current position, and then increments the position.- Returns:
- The char at the buffer's current position
- Throws:
BufferUnderflowException- If the buffer's current position is not smaller than its limit
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put
Relative put method (optional operation).Writes the given char into this buffer at the current position, and then increments the position.
- Parameters:
c- The char to be written- Returns:
- This buffer
- Throws:
BufferOverflowException- If this buffer's current position is not smaller than its limitReadOnlyBufferException- If this buffer is read-only
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get
public abstract char get(int index) Absolute get method. Reads the char at the given index.- Parameters:
index- The index from which the char will be read- Returns:
- The char at the given index
- Throws:
IndexOutOfBoundsException- Ifindexis negative or not smaller than the buffer's limit
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put
Absolute put method (optional operation).Writes the given char into this buffer at the given index.
- Parameters:
index- The index at which the char will be writtenc- The char value to be written- Returns:
- This buffer
- Throws:
IndexOutOfBoundsException- Ifindexis negative or not smaller than the buffer's limitReadOnlyBufferException- If this buffer is read-only
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get
Relative bulk get method.This method transfers chars from this buffer into the given destination array. If there are fewer chars remaining in the buffer than are required to satisfy the request, that is, if
length>remaining(), then no chars are transferred and aBufferUnderflowExceptionis thrown.Otherwise, this method copies
lengthchars from this buffer into the given array, starting at the current position of this buffer and at the given offset in the array. The position of this buffer is then incremented bylength.In other words, an invocation of this method of the form
src.get(dst, off, len)has exactly the same effect as the loopexcept that it first checks that there are sufficient chars in this buffer and it is potentially much more efficient.for (int i = off; i < off + len; i++) dst[i] = src.get();- Parameters:
dst- The array into which chars are to be writtenoffset- The offset within the array of the first char to be written; must be non-negative and no larger thandst.lengthlength- The maximum number of chars to be written to the given array; must be non-negative and no larger thandst.length - offset- Returns:
- This buffer
- Throws:
BufferUnderflowException- If there are fewer thanlengthchars remaining in this bufferIndexOutOfBoundsException- If the preconditions on theoffsetandlengthparameters do not hold
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get
Relative bulk get method.This method transfers chars from this buffer into the given destination array. An invocation of this method of the form
src.get(a)behaves in exactly the same way as the invocationsrc.get(a, 0, a.length)- Parameters:
dst- The destination array- Returns:
- This buffer
- Throws:
BufferUnderflowException- If there are fewer thanlengthchars remaining in this buffer
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get
Absolute bulk get method.This method transfers
lengthchars from this buffer into the given array, starting at the given index in this buffer and at the given offset in the array. The position of this buffer is unchanged.An invocation of this method of the form
src.get(index, dst, offset, length)has exactly the same effect as the following loop except that it first checks the consistency of the supplied parameters and it is potentially much more efficient:for (int i = offset, j = index; i < offset + length; i++, j++) dst[i] = src.get(j);- Parameters:
index- The index in this buffer from which the first char will be read; must be non-negative and less thanlimit()dst- The destination arrayoffset- The offset within the array of the first char to be written; must be non-negative and less thandst.lengthlength- The number of chars to be written to the given array; must be non-negative and no larger than the smaller oflimit() - indexanddst.length - offset- Returns:
- This buffer
- Throws:
IndexOutOfBoundsException- If the preconditions on theindex,offset, andlengthparameters do not hold- Since:
- 13
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get
Absolute bulk get method.This method transfers chars from this buffer into the given destination array. The position of this buffer is unchanged. An invocation of this method of the form
src.get(index, dst)behaves in exactly the same way as the invocation:src.get(index, dst, 0, dst.length)- Parameters:
index- The index in this buffer from which the first char will be read; must be non-negative and less thanlimit()dst- The destination array- Returns:
- This buffer
- Throws:
IndexOutOfBoundsException- Ifindexis negative, not smaller thanlimit(), orlimit() - index < dst.length- Since:
- 13
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put
Relative bulk put method (optional operation).This method transfers the chars remaining in the given source buffer into this buffer. If there are more chars remaining in the source buffer than in this buffer, that is, if
src.remaining()>remaining(), then no chars are transferred and aBufferOverflowExceptionis thrown.Otherwise, this method copies n =
src.remaining()chars from the given buffer into this buffer, starting at each buffer's current position. The positions of both buffers are then incremented by n.In other words, an invocation of this method of the form
dst.put(src)has exactly the same effect as the loopexcept that it first checks that there is sufficient space in this buffer and it is potentially much more efficient. If this buffer and the source buffer share the same backing array or memory, then the result will be as if the source elements were first copied to an intermediate location before being written into this buffer.while (src.hasRemaining()) dst.put(src.get());- Parameters:
src- The source buffer from which chars are to be read; must not be this buffer- Returns:
- This buffer
- Throws:
BufferOverflowException- If there is insufficient space in this buffer for the remaining chars in the source bufferIllegalArgumentException- If the source buffer is this bufferReadOnlyBufferException- If this buffer is read-only
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put
Absolute bulk put method (optional operation).This method transfers
lengthchars into this buffer from the given source buffer, starting at the givenoffsetin the source buffer and the givenindexin this buffer. The positions of both buffers are unchanged.In other words, an invocation of this method of the form
dst.put(index, src, offset, length)has exactly the same effect as the loopexcept that it first checks the consistency of the supplied parameters and it is potentially much more efficient. If this buffer and the source buffer share the same backing array or memory, then the result will be as if the source elements were first copied to an intermediate location before being written into this buffer.for (int i = offset, j = index; i < offset + length; i++, j++) dst.put(j, src.get(i));- Parameters:
index- The index in this buffer at which the first char will be written; must be non-negative and less thanlimit()src- The buffer from which chars are to be readoffset- The index within the source buffer of the first char to be read; must be non-negative and less thansrc.limit()length- The number of chars to be read from the given buffer; must be non-negative and no larger than the smaller oflimit() - indexandsrc.limit() - offset- Returns:
- This buffer
- Throws:
IndexOutOfBoundsException- If the preconditions on theindex,offset, andlengthparameters do not holdReadOnlyBufferException- If this buffer is read-only- Since:
- 16
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put
Relative bulk put method (optional operation).This method transfers chars into this buffer from the given source array. If there are more chars to be copied from the array than remain in this buffer, that is, if
length>remaining(), then no chars are transferred and aBufferOverflowExceptionis thrown.Otherwise, this method copies
lengthchars from the given array into this buffer, starting at the given offset in the array and at the current position of this buffer. The position of this buffer is then incremented bylength.In other words, an invocation of this method of the form
dst.put(src, off, len)has exactly the same effect as the loopexcept that it first checks that there is sufficient space in this buffer and it is potentially much more efficient.for (int i = off; i < off + len; i++) dst.put(src[i]);- Parameters:
src- The array from which chars are to be readoffset- The offset within the array of the first char to be read; must be non-negative and no larger thansrc.lengthlength- The number of chars to be read from the given array; must be non-negative and no larger thansrc.length - offset- Returns:
- This buffer
- Throws:
BufferOverflowException- If there is insufficient space in this bufferIndexOutOfBoundsException- If the preconditions on theoffsetandlengthparameters do not holdReadOnlyBufferException- If this buffer is read-only
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put
Relative bulk put method (optional operation).This method transfers the entire content of the given source char array into this buffer. An invocation of this method of the form
dst.put(a)behaves in exactly the same way as the invocationdst.put(a, 0, a.length)- Parameters:
src- The source array- Returns:
- This buffer
- Throws:
BufferOverflowException- If there is insufficient space in this bufferReadOnlyBufferException- If this buffer is read-only
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put
Absolute bulk put method (optional operation).This method transfers
lengthchars from the given array, starting at the given offset in the array and at the given index in this buffer. The position of this buffer is unchanged.An invocation of this method of the form
dst.put(index, src, offset, length)has exactly the same effect as the following loop except that it first checks the consistency of the supplied parameters and it is potentially much more efficient:for (int i = offset, j = index; i < offset + length; i++, j++) dst.put(j, src[i]);- Parameters:
index- The index in this buffer at which the first char will be written; must be non-negative and less thanlimit()src- The array from which chars are to be readoffset- The offset within the array of the first char to be read; must be non-negative and less thansrc.lengthlength- The number of chars to be read from the given array; must be non-negative and no larger than the smaller oflimit() - indexandsrc.length - offset- Returns:
- This buffer
- Throws:
IndexOutOfBoundsException- If the preconditions on theindex,offset, andlengthparameters do not holdReadOnlyBufferException- If this buffer is read-only- Since:
- 13
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put
Absolute bulk put method (optional operation).This method copies chars into this buffer from the given source array. The position of this buffer is unchanged. An invocation of this method of the form
dst.put(index, src)behaves in exactly the same way as the invocation:dst.put(index, src, 0, src.length);- Parameters:
index- The index in this buffer at which the first char will be written; must be non-negative and less thanlimit()src- The array from which chars are to be read- Returns:
- This buffer
- Throws:
IndexOutOfBoundsException- Ifindexis negative, not smaller thanlimit(), orlimit() - index < src.lengthReadOnlyBufferException- If this buffer is read-only- Since:
- 13
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put
Relative bulk put method (optional operation).This method transfers chars from the given string into this buffer. If there are more chars to be copied from the string than remain in this buffer, that is, if
end - start>remaining(), then no chars are transferred and aBufferOverflowExceptionis thrown.Otherwise, this method copies n =
end-startchars from the given string into this buffer, starting at the givenstartindex and at the current position of this buffer. The position of this buffer is then incremented by n.In other words, an invocation of this method of the form
dst.put(src, start, end)has exactly the same effect as the loopexcept that it first checks that there is sufficient space in this buffer and it is potentially much more efficient.for (int i = start; i < end; i++) dst.put(src.charAt(i));- Parameters:
src- The string from which chars are to be readstart- The offset within the string of the first char to be read; must be non-negative and no larger thanstring.length()end- The offset within the string of the last char to be read, plus one; must be non-negative and no larger thanstring.length()- Returns:
- This buffer
- Throws:
BufferOverflowException- If there is insufficient space in this bufferIndexOutOfBoundsException- If the preconditions on thestartandendparameters do not holdReadOnlyBufferException- If this buffer is read-only
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put
Relative bulk put method (optional operation).This method transfers the entire content of the given source string into this buffer. An invocation of this method of the form
dst.put(s)behaves in exactly the same way as the invocationdst.put(s, 0, s.length())- Parameters:
src- The source string- Returns:
- This buffer
- Throws:
BufferOverflowException- If there is insufficient space in this bufferReadOnlyBufferException- If this buffer is read-only
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hasArray
public final boolean hasArray()Tells whether or not this buffer is backed by an accessible char array.If this method returns
truethen thearrayandarrayOffsetmethods may safely be invoked. -
array
public final char[] array()Returns the char array that backs this buffer (optional operation).Modifications to this buffer's content will cause the returned array's content to be modified, and vice versa.
Invoke the
hasArraymethod before invoking this method in order to ensure that this buffer has an accessible backing array.- Specified by:
arrayin classBuffer- Returns:
- The array that backs this buffer
- Throws:
ReadOnlyBufferException- If this buffer is backed by an array but is read-onlyUnsupportedOperationException- If this buffer is not backed by an accessible array
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arrayOffset
public final int arrayOffset()Returns the offset within this buffer's backing array of the first element of the buffer (optional operation).If this buffer is backed by an array then buffer position p corresponds to array index p +
arrayOffset().Invoke the
hasArraymethod before invoking this method in order to ensure that this buffer has an accessible backing array.- Specified by:
arrayOffsetin classBuffer- Returns:
- The offset within this buffer's array of the first element of the buffer
- Throws:
ReadOnlyBufferException- If this buffer is backed by an array but is read-onlyUnsupportedOperationException- If this buffer is not backed by an accessible array
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position
Sets this buffer's position. If the mark is defined and larger than the new position then it is discarded. -
limit
Sets this buffer's limit. If the position is larger than the new limit then it is set to the new limit. If the mark is defined and larger than the new limit then it is discarded. -
mark
Sets this buffer's mark at its position. -
reset
Resets this buffer's position to the previously-marked position.Invoking this method neither changes nor discards the mark's value.
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clear
Clears this buffer. The position is set to zero, the limit is set to the capacity, and the mark is discarded.Invoke this method before using a sequence of channel-read or put operations to fill this buffer. For example:
buf.clear(); // Prepare buffer for reading in.read(buf); // Read dataThis method does not actually erase the data in the buffer, but it is named as if it did because it will most often be used in situations in which that might as well be the case.
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flip
Flips this buffer. The limit is set to the current position and then the position is set to zero. If the mark is defined then it is discarded.After a sequence of channel-read or put operations, invoke this method to prepare for a sequence of channel-write or relative get operations. For example:
buf.put(magic); // Prepend header in.read(buf); // Read data into rest of buffer buf.flip(); // Flip buffer out.write(buf); // Write header + data to channelThis method is often used in conjunction with the
compactmethod when transferring data from one place to another. -
rewind
Rewinds this buffer. The position is set to zero and the mark is discarded.Invoke this method before a sequence of channel-write or get operations, assuming that the limit has already been set appropriately. For example:
out.write(buf); // Write remaining data buf.rewind(); // Rewind buffer buf.get(array); // Copy data into array -
compact
Compacts this buffer (optional operation).The chars between the buffer's current position and its limit, if any, are copied to the beginning of the buffer. That is, the char at index p =
position()is copied to index zero, the char at index p + 1 is copied to index one, and so forth until the char at indexlimit()- 1 is copied to index n =limit()-1- p. The buffer's position is then set to n+1 and its limit is set to its capacity. The mark, if defined, is discarded.The buffer's position is set to the number of chars copied, rather than to zero, so that an invocation of this method can be followed immediately by an invocation of another relative put method.
- Returns:
- This buffer
- Throws:
ReadOnlyBufferException- If this buffer is read-only
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isDirect
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hashCode
public int hashCode()Returns the current hash code of this buffer.The hash code of a char buffer depends only upon its remaining elements; that is, upon the elements from
position()up to, and including, the element atlimit()-1.Because buffer hash codes are content-dependent, it is inadvisable to use buffers as keys in hash maps or similar data structures unless it is known that their contents will not change.
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equals
Tells whether or not this buffer is equal to another object.Two char buffers are equal if, and only if,
They have the same element type,
They have the same number of remaining elements, and
The two sequences of remaining elements, considered independently of their starting positions, are pointwise equal.
A char buffer is not equal to any other type of object.
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compareTo
Compares this buffer to another.Two char buffers are compared by comparing their sequences of remaining elements lexicographically, without regard to the starting position of each sequence within its corresponding buffer. Pairs of
charelements are compared as if by invokingCharacter.compare(char,char).A char buffer is not comparable to any other type of object.
- Specified by:
compareToin interfaceComparable<CharBuffer>- Parameters:
that- the object to be compared.- Returns:
- A negative integer, zero, or a positive integer as this buffer is less than, equal to, or greater than the given buffer
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mismatch
Finds and returns the relative index of the first mismatch between this buffer and a given buffer. The index is relative to thepositionof each buffer and will be in the range of 0 (inclusive) up to the smaller of theremainingelements in each buffer (exclusive).If the two buffers share a common prefix then the returned index is the length of the common prefix and it follows that there is a mismatch between the two buffers at that index within the respective buffers. If one buffer is a proper prefix of the other then the returned index is the smaller of the remaining elements in each buffer, and it follows that the index is only valid for the buffer with the larger number of remaining elements. Otherwise, there is no mismatch.
- Parameters:
that- The byte buffer to be tested for a mismatch with this buffer- Returns:
- The relative index of the first mismatch between this and the given buffer, otherwise -1 if no mismatch.
- Since:
- 11
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toString
Returns a string containing the characters in this buffer.The first character of the resulting string will be the character at this buffer's position, while the last character will be the character at index
limit()- 1. Invoking this method does not change the buffer's position.- Specified by:
toStringin interfaceCharSequence- Overrides:
toStringin classObject- Returns:
- The specified string
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length
public final int length()Returns the length of this character buffer.When viewed as a character sequence, the length of a character buffer is simply the number of characters between the position (inclusive) and the limit (exclusive); that is, it is equivalent to
remaining().- Specified by:
lengthin interfaceCharSequence- Returns:
- The length of this character buffer
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isEmpty
public final boolean isEmpty()Returnstrueif this character buffer is empty.- Specified by:
isEmptyin interfaceCharSequence- Returns:
trueif there are0remaining characters, otherwisefalse- Since:
- 15
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charAt
public final char charAt(int index) Reads the character at the given index relative to the current position.- Specified by:
charAtin interfaceCharSequence- Parameters:
index- The index of the character to be read, relative to the position; must be non-negative and smaller thanremaining()- Returns:
- The character at index
position() + index - Throws:
IndexOutOfBoundsException- If the preconditions onindexdo not hold
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subSequence
Creates a new character buffer that represents the specified subsequence of this buffer, relative to the current position.The new buffer will share this buffer's content; that is, if the content of this buffer is mutable then modifications to one buffer will cause the other to be modified. The new buffer's capacity will be that of this buffer, its position will be
position()+start, its limit will beposition()+end, and its byte order will be identical to that of this buffer. The new buffer will be direct if, and only if, this buffer is direct, and it will be read-only if, and only if, this buffer is read-only.- Specified by:
subSequencein interfaceCharSequence- Parameters:
start- The index, relative to the current position, of the first character in the subsequence; must be non-negative and no larger thanremaining()end- The index, relative to the current position, of the character following the last character in the subsequence; must be no smaller thanstartand no larger thanremaining()- Returns:
- The new character buffer
- Throws:
IndexOutOfBoundsException- If the preconditions onstartandenddo not hold
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append
Appends the specified character sequence to this buffer (optional operation).An invocation of this method of the form
dst.append(csq)behaves in exactly the same way as the invocationdst.put(csq.toString())Depending on the specification of
toStringfor the character sequencecsq, the entire sequence may not be appended. For instance, invoking thetoStringmethod of a character buffer will return a subsequence whose content depends upon the buffer's position and limit.- Specified by:
appendin interfaceAppendable- Parameters:
csq- The character sequence to append. Ifcsqisnull, then the four characters"null"are appended to this character buffer.- Returns:
- This buffer
- Throws:
BufferOverflowException- If there is insufficient space in this bufferReadOnlyBufferException- If this buffer is read-only- Since:
- 1.5
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append
Appends a subsequence of the specified character sequence to this buffer (optional operation).An invocation of this method of the form
dst.append(csq, start, end)whencsqis notnull, behaves in exactly the same way as the invocationdst.put(csq.subSequence(start, end).toString())- Specified by:
appendin interfaceAppendable- Parameters:
csq- The character sequence from which a subsequence will be appended. Ifcsqisnull, then characters will be appended as ifcsqcontained the four characters"null".start- The index of the first character in the subsequenceend- The index of the character following the last character in the subsequence- Returns:
- This buffer
- Throws:
BufferOverflowException- If there is insufficient space in this bufferIndexOutOfBoundsException- Ifstartorendare negative,startis greater thanend, orendis greater thancsq.length()ReadOnlyBufferException- If this buffer is read-only- Since:
- 1.5
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append
Appends the specified char to this buffer (optional operation).An invocation of this method of the form
dst.append(c)behaves in exactly the same way as the invocationdst.put(c)- Specified by:
appendin interfaceAppendable- Parameters:
c- The 16-bit char to append- Returns:
- This buffer
- Throws:
BufferOverflowException- If there is insufficient space in this bufferReadOnlyBufferException- If this buffer is read-only- Since:
- 1.5
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order
Retrieves this buffer's byte order.The byte order of a char buffer created by allocation or by wrapping an existing
chararray is thenative orderof the underlying hardware. The byte order of a char buffer created as a view of a byte buffer is that of the byte buffer at the moment that the view is created.- Returns:
- This buffer's byte order
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