目錄
簡介
字段hb,offset,isReadOnly，2個構造函數
方法allocate,4個wrap,read,slice,duplicate,asReadOnlyBuffer
方法4個get,7個put
方法hasArray,array,arrayOffset,compact,isDirect,equals,compareTo
方法2個toString,length,charAt,subSequence,3個append,order,chars
簡介
由于CharBuffer與ByteBuffer很像，大部分地方都是将byte直接改成char，是以這部分不進行翻譯和注釋，隻對CharBuffer特有的一些地方進行注釋
package java.nio;
import java.io.IOException;
import java.util.Spliterator;
import java.util.stream.StreamSupport;
import java.util.stream.IntStream;
/**
* 一個字元緩沖區。
*
* <p>
* 這個類定義了字元緩沖區上的四類操作:
*
* <ul>
*
* <li>
* <p>
* 讀取和寫入單個字元的絕對和相對get和put方法;
* </p>
* </li>
*
* <li>
* <p>
* 相對批量擷取方法，該方法将連續的字元序列從該緩沖區轉移到數組中;和
* </p>
* </li>
*
* <li>
* <p>
* 将連續的字元序列從一個字元數組、字元串或其他字元緩沖區轉移到這個緩沖區的相對批量放置方法;和
* </p>
* </li>
*
* <li>
* <p>
* 壓縮、複制和切片char緩沖區的方法。
* </p>
* </li>
*
* </ul>
*
* <p>
* Char緩沖區可以通過配置設定allocate(即為緩沖區的内容配置設定空間)、
*将現有的Char數組或字元串wrap到緩沖區中
*或建立現有位元組緩沖區的視圖來建立。
*
* <p>
* 與位元組緩沖區一樣，char緩沖區也是直接的或非直接的。
* 通過這個類的wrap方法建立的char緩沖區将是非直接的。
* 作為位元組緩沖區的視圖建立的char緩沖區将是直接的，并且隻有在位元組緩沖區本身是直接的情況下。
* charbuffer是否是直接的可以通過調用isDirect方法來确定。
* </p>
*
* <p>
* 這個類實作了CharSequence接口，
* 這樣就可以在字元序列被接受的地方使用字元緩沖區，
* 例如在正規表達式包java.util.regex中。
* </p>
*
* <p>
* 該類中不需要傳回值的方法被指定為傳回調用它們的緩沖區。
*這允許方法調用被連結。語句序列
*
* The sequence of statements
*
* <blockquote>
*
* <pre>
* cb.put("text/");
* cb.put(subtype);
* cb.put("; charset=");
* cb.put(enc);
* </pre>
*
* </blockquote>
*
* can, for example, be replaced by the single statement
*
* <blockquote>
*
* <pre>
* cb.put("text/").put(subtype).put("; charset=").put(enc);
* </pre>
*
* </blockquote>
*
*
* @author Mark Reinhold
* @author JSR-51 Expert Group
* @since 1.4
*/
public abstract class CharBuffer extends Buffer implements Comparable<CharBuffer>, Appendable, CharSequence, Readable
字段hb,offset,isReadOnly，2個構造函數
// These fields are declared here rather than in Heap-X-Buffer in order to
// reduce the number of virtual method invocations needed to access these
// values, which is especially costly when coding small buffers.
//
final char[] hb; // Non-null only for heap buffers
final int offset;
boolean isReadOnly; // Valid only for heap buffers
// Creates a new buffer with the given mark, position, limit, capacity,
// backing array, and array offset
//
CharBuffer(int mark, int pos, int lim, int cap, // package-private
char[] hb, int offset) {
super(mark, pos, lim, cap);
this.hb = hb;
this.offset = offset;
}
// Creates a new buffer with the given mark, position, limit, and capacity
//
CharBuffer(int mark, int pos, int lim, int cap) { // package-private
this(mark, pos, lim, cap, null, 0);
}
方法allocate,4個wrap,read,slice,duplicate,asReadOnlyBuffer
/**
* Allocates a new char buffer.
*
* <p>
* The new buffer's position will be zero, its limit will be its capacity, its
* mark will be undefined, and each of its elements will be initialized to zero.
* It will have a {@link #array backing array}, and its {@link #arrayOffset
* array offset} will be zero.
*
* @param capacity The new buffer's capacity, in chars
*
* @return The new char buffer
*
* @throws IllegalArgumentException If the <tt>capacity</tt> is a negative
* integer
*/
public static CharBuffer allocate(int capacity) {
if (capacity < 0)
throw new IllegalArgumentException();
return new HeapCharBuffer(capacity, capacity);
}
/**
* Wraps a char array into a buffer.
*
* <p>
* 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 <tt>array.length</tt>, its position will be
* <tt>offset</tt>, its limit will be <tt>offset + length</tt>, and its mark
* will be undefined. Its {@link #array backing array} will be the given array,
* and its {@link #arrayOffset array offset} will be zero.
* </p>
*
* @param array The array that will back the new buffer
*
* @param offset The offset of the subarray to be used; must be non-negative and
* no larger than <tt>array.length</tt>. The new buffer's position
* will be set to this value.
*
* @param length The length of the subarray to be used; must be non-negative and
* no larger than <tt>array.length - offset</tt>. The new buffer's
* limit will be set to <tt>offset + length</tt>.
*
* @return The new char buffer
*
* @throws IndexOutOfBoundsException If the preconditions on the <tt>offset</tt>
* and <tt>length</tt> parameters do not hold
*/
public static CharBuffer wrap(char[] array, int offset, int length) {
try {
return new HeapCharBuffer(array, offset, length);
} catch (IllegalArgumentException x) {
throw new IndexOutOfBoundsException();
}
}
/**
* Wraps a char array into a buffer.
*
* <p>
* 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 <tt>array.length</tt>, its position will
* be zero, and its mark will be undefined. Its {@link #array backing array}
* will be the given array, and its {@link #arrayOffset array offset>} will be
* zero.
* </p>
*
* @param array The array that will back this buffer
*
* @return The new char buffer
*/
public static CharBuffer wrap(char[] array) {
return wrap(array, 0, array.length);
}
/**
* 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.
*
* @param target the buffer to read characters into
* @return The number of characters added to the buffer, or -1 if this source of
* characters is at its end
* @throws IOException if an I/O error occurs
* @throws NullPointerException if target is null
* @throws ReadOnlyBufferException if target is a read only buffer
* @since 1.5
*/
public int read(CharBuffer target) throws IOException {
// Determine the number of bytes n that can be transferred
int targetRemaining = target.remaining();
int remaining = remaining();
if (remaining == 0)
return -1;
int n = Math.min(remaining, targetRemaining);
int limit = limit();
// Set source limit to prevent target overflow
if (targetRemaining < remaining)
limit(position() + n);
try {
if (n > 0)
target.put(this);
} finally {
limit(limit); // restore real limit
}
return n;
}
/**
* Wraps a character sequence into a buffer.
*
* <p>
* The content of the new, read-only buffer will be the content of the given
* character sequence. The buffer's capacity will be <tt>csq.length()</tt>, its
* position will be <tt>start</tt>, its limit will be <tt>end</tt>, and its mark
* will be undefined.
* </p>
*
* @param csq The character sequence from which the new character buffer is to
* be created
*
* @param start The index of the first character to be used; must be
* non-negative and no larger than <tt>csq.length()</tt>. The new
* buffer's position will be set to this value.
*
* @param end The index of the character following the last character to be
* used; must be no smaller than <tt>start</tt> and no larger than
* <tt>csq.length()</tt>. The new buffer's limit will be set to
* this value.
*
* @return The new character buffer
*
* @throws IndexOutOfBoundsException If the preconditions on the <tt>start</tt>
* and <tt>end</tt> parameters do not hold
*/
public static CharBuffer wrap(CharSequence csq, int start, int end) {
try {
return new StringCharBuffer(csq, start, end);
} catch (IllegalArgumentException x) {
throw new IndexOutOfBoundsException();
}
}
/**
* Wraps a character sequence into a buffer.
*
* <p>
* 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
* <tt>csq.length()</tt>, its position will be zero, and its mark will be
* undefined.
* </p>
*
* @param csq The character sequence from which the new character buffer is to
* be created
*
* @return The new character buffer
*/
public static CharBuffer wrap(CharSequence csq) {
return wrap(csq, 0, csq.length());
}
/**
* Creates a new char buffer whose content is a shared subsequence of this
* buffer's content.
*
* <p>
* 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.
*
* <p>
* The new buffer's position will be zero, its capacity and its limit will be
* the number of chars remaining in this buffer, and its mark will be undefined.
* 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.
* </p>
*
* @return The new char buffer
*/
public abstract CharBuffer slice();
/**
* Creates a new char buffer that shares this buffer's content.
*
* <p>
* 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.
*
* <p>
* The new buffer's capacity, limit, position, and mark values 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.
* </p>
*
* @return The new char buffer
*/
public abstract CharBuffer duplicate();
/**
* Creates a new, read-only char buffer that shares this buffer's content.
*
* <p>
* 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.
*
* <p>
* The new buffer's capacity, limit, position, and mark values will be identical
* to those of this buffer.
*
* <p>
* If this buffer is itself read-only then this method behaves in exactly the
* same way as the {@link #duplicate duplicate} method.
* </p>
*
* @return The new, read-only char buffer
*/
public abstract CharBuffer asReadOnlyBuffer();
方法4個get,7個put
// -- Singleton get/put methods --
/**
* Relative <i>get</i> method. Reads the char at this buffer's current position,
* and then increments the position.
*
* @return The char at the buffer's current position
*
* @throws BufferUnderflowException If the buffer's current position is not
* smaller than its limit
*/
public abstract char get();
/**
* Relative <i>put</i> method <i>(optional operation)</i>.
*
* <p>
* Writes the given char into this buffer at the current position, and then
* increments the position.
* </p>
*
* @param c The char to be written
*
* @return This buffer
*
* @throws BufferOverflowException If this buffer's current position is not
* smaller than its limit
*
* @throws ReadOnlyBufferException If this buffer is read-only
*/
public abstract CharBuffer put(char c);
/**
* Absolute <i>get</i> method. Reads the char at the given index.
*
* @param index The index from which the char will be read
*
* @return The char at the given index
*
* @throws IndexOutOfBoundsException If <tt>index</tt> is negative or not
* smaller than the buffer's limit
*/
public abstract char get(int index);
/**
* Absolute <i>get</i> method. Reads the char at the given index without any
* validation of the index.
*
* @param index The index from which the char will be read
*
* @return The char at the given index
*/
abstract char getUnchecked(int index); // package-private
/**
* Absolute <i>put</i> method <i>(optional operation)</i>.
*
* <p>
* Writes the given char into this buffer at the given index.
* </p>
*
* @param index The index at which the char will be written
*
* @param c The char value to be written
*
* @return This buffer
*
* @throws IndexOutOfBoundsException If <tt>index</tt> is negative or not
* smaller than the buffer's limit
*
* @throws ReadOnlyBufferException If this buffer is read-only
*/
public abstract CharBuffer put(int index, char c);
// -- Bulk get operations --
/**
* Relative bulk <i>get</i> method.
*
* <p>
* 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
* <tt>length</tt> <tt>></tt> <tt>remaining()</tt>, then no chars
* are transferred and a {@link BufferUnderflowException} is thrown.
*
* <p>
* Otherwise, this method copies <tt>length</tt> chars 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 by
* <tt>length</tt>.
*
* <p>
* In other words, an invocation of this method of the form
* <tt>src.get(dst, off, len)</tt> has exactly the same effect as the
* loop
*
* <pre>
* {@code
* for (int i = off; i < off + len; i++)
* dst[i] = src.get():
* }
* </pre>
*
* except that it first checks that there are sufficient chars in this buffer
* and it is potentially much more efficient.
*
* @param dst The array into which chars are to be written
*
* @param offset The offset within the array of the first char to be written;
* must be non-negative and no larger than <tt>dst.length</tt>
*
* @param length The maximum number of chars to be written to the given array;
* must be non-negative and no larger than
* <tt>dst.length - offset</tt>
*
* @return This buffer
*
* @throws BufferUnderflowException If there are fewer than <tt>length</tt>
* chars remaining in this buffer
*
* @throws IndexOutOfBoundsException If the preconditions on the <tt>offset</tt>
* and <tt>length</tt> parameters do not hold
*/
public CharBuffer get(char[] dst, int offset, int length) {
checkBounds(offset, length, dst.length);
if (length > remaining())
throw new BufferUnderflowException();
int end = offset + length;
for (int i = offset; i < end; i++)
dst[i] = get();
return this;
}
/**
* Relative bulk <i>get</i> method.
*
* <p>
* This method transfers chars from this buffer into the given destination
* array. An invocation of this method of the form <tt>src.get(a)</tt> behaves
* in exactly the same way as the invocation
*
* <pre>
* src.get(a, 0, a.length)
* </pre>
*
* @param dst The destination array
*
* @return This buffer
*
* @throws BufferUnderflowException If there are fewer than <tt>length</tt>
* chars remaining in this buffer
*/
public CharBuffer get(char[] dst) {
return get(dst, 0, dst.length);
}
// -- Bulk put operations --
/**
* Relative bulk <i>put</i> method <i>(optional operation)</i>.
*
* <p>
* 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
* <tt>src.remaining()</tt> <tt>></tt> <tt>remaining()</tt>, then
* no chars are transferred and a {@link BufferOverflowException} is thrown.
*
* <p>
* Otherwise, this method copies <i>n</i> = <tt>src.remaining()</tt>
* chars from the given buffer into this buffer, starting at each buffer's
* current position. The positions of both buffers are then incremented by
* <i>n</i>.
*
* <p>
* In other words, an invocation of this method of the form
* <tt>dst.put(src)</tt> has exactly the same effect as the loop
*
* <pre>
* while (src.hasRemaining())
* dst.put(src.get());
* </pre>
*
* except that it first checks that there is sufficient space in this buffer and
* it is potentially much more efficient.
*
* @param src The source buffer from which chars are to be read; must not be
* this buffer
*
* @return This buffer
*
* @throws BufferOverflowException If there is insufficient space in this
* buffer for the remaining chars in the source
* buffer
*
* @throws IllegalArgumentException If the source buffer is this buffer
*
* @throws ReadOnlyBufferException If this buffer is read-only
*/
public CharBuffer put(CharBuffer src) {
if (src == this)
throw new IllegalArgumentException();
if (isReadOnly())
throw new ReadOnlyBufferException();
int n = src.remaining();
if (n > remaining())
throw new BufferOverflowException();
for (int i = 0; i < n; i++)
put(src.get());
return this;
}
/**
* Relative bulk <i>put</i> method <i>(optional operation)</i>.
*
* <p>
* 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 <tt>length</tt> <tt>></tt> <tt>remaining()</tt>,
* then no chars are transferred and a {@link BufferOverflowException} is
* thrown.
*
* <p>
* Otherwise, this method copies <tt>length</tt> chars 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 by
* <tt>length</tt>.
*
* <p>
* In other words, an invocation of this method of the form
* <tt>dst.put(src, off, len)</tt> has exactly the same effect as the
* loop
*
* <pre>
* {@code
* for (int i = off; i < off + len; i++)
* dst.put(a[i]);
* }
* </pre>
*
* except that it first checks that there is sufficient space in this buffer and
* it is potentially much more efficient.
*
* @param src The array from which chars are to be read
*
* @param offset The offset within the array of the first char to be read; must
* be non-negative and no larger than <tt>array.length</tt>
*
* @param length The number of chars to be read from the given array; must be
* non-negative and no larger than <tt>array.length - offset</tt>
*
* @return This buffer
*
* @throws BufferOverflowException If there is insufficient space in this
* buffer
*
* @throws IndexOutOfBoundsException If the preconditions on the <tt>offset</tt>
* and <tt>length</tt> parameters do not hold
*
* @throws ReadOnlyBufferException If this buffer is read-only
*/
public CharBuffer put(char[] src, int offset, int length) {
checkBounds(offset, length, src.length);
if (length > remaining())
throw new BufferOverflowException();
int end = offset + length;
for (int i = offset; i < end; i++)
this.put(src[i]);
return this;
}
/**
* Relative bulk <i>put</i> method <i>(optional operation)</i>.
*
* <p>
* This method transfers the entire content of the given source char array into
* this buffer. An invocation of this method of the form <tt>dst.put(a)</tt>
* behaves in exactly the same way as the invocation
*
* <pre>
* dst.put(a, 0, a.length)
* </pre>
*
* @param src The source array
*
* @return This buffer
*
* @throws BufferOverflowException If there is insufficient space in this buffer
*
* @throws ReadOnlyBufferException If this buffer is read-only
*/
public final CharBuffer put(char[] src) {
return put(src, 0, src.length);
}
/**
* Relative bulk <i>put</i> method <i>(optional operation)</i>.
*
* <p>
* 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
* <tt>end - start</tt> <tt>></tt> <tt>remaining()</tt>,
* then no chars are transferred and a {@link BufferOverflowException} is
* thrown.
*
* <p>
* Otherwise, this method copies
* <i>n</i> = <tt>end</tt> - <tt>start</tt> chars from the
* given string into this buffer, starting at the given <tt>start</tt> index and
* at the current position of this buffer. The position of this buffer is then
* incremented by <i>n</i>.
*
* <p>
* In other words, an invocation of this method of the form
* <tt>dst.put(src, start, end)</tt> has exactly the same effect as
* the loop
*
* <pre>
* {@code
* for (int i = start; i < end; i++)
* dst.put(src.charAt(i));
* }
* </pre>
*
* except that it first checks that there is sufficient space in this buffer and
* it is potentially much more efficient.
*
* @param src The string from which chars are to be read
*
* @param start The offset within the string of the first char to be read; must
* be non-negative and no larger than <tt>string.length()</tt>
*
* @param end The offset within the string of the last char to be read, plus
* one; must be non-negative and no larger than
* <tt>string.length()</tt>
*
* @return This buffer
*
* @throws BufferOverflowException If there is insufficient space in this
* buffer
*
* @throws IndexOutOfBoundsException If the preconditions on the <tt>start</tt>
* and <tt>end</tt> parameters do not hold
*
* @throws ReadOnlyBufferException If this buffer is read-only
*/
public CharBuffer put(String src, int start, int end) {
checkBounds(start, end - start, src.length());
if (isReadOnly())
throw new ReadOnlyBufferException();
if (end - start > remaining())
throw new BufferOverflowException();
for (int i = start; i < end; i++)
this.put(src.charAt(i));
return this;
}
/**
* Relative bulk <i>put</i> method <i>(optional operation)</i>.
*
* <p>
* This method transfers the entire content of the given source string into this
* buffer. An invocation of this method of the form <tt>dst.put(s)</tt> behaves
* in exactly the same way as the invocation
*
* <pre>
* dst.put(s, 0, s.length())
* </pre>
*
* @param src The source string
*
* @return This buffer
*
* @throws BufferOverflowException If there is insufficient space in this buffer
*
* @throws ReadOnlyBufferException If this buffer is read-only
*/
public final CharBuffer put(String src) {
return put(src, 0, src.length());
}
方法hasArray,array,arrayOffset,compact,isDirect,equals,compareTo
// -- Other stuff --
/**
* Tells whether or not this buffer is backed by an accessible char array.
*
* <p>
* If this method returns <tt>true</tt> then the {@link #array() array} and
* {@link #arrayOffset() arrayOffset} methods may safely be invoked.
* </p>
*
* @return <tt>true</tt> if, and only if, this buffer is backed by an array and
* is not read-only
*/
public final boolean hasArray() {
return (hb != null) && !isReadOnly;
}
/**
* Returns the char array that backs this buffer <i>(optional
* operation)</i>.
*
* <p>
* Modifications to this buffer's content will cause the returned array's
* content to be modified, and vice versa.
*
* <p>
* Invoke the {@link #hasArray hasArray} method before invoking this method in
* order to ensure that this buffer has an accessible backing array.
* </p>
*
* @return The array that backs this buffer
*
* @throws ReadOnlyBufferException If this buffer is backed by an array
* but is read-only
*
* @throws UnsupportedOperationException If this buffer is not backed by an
* accessible array
*/
public final char[] array() {
if (hb == null)
throw new UnsupportedOperationException();
if (isReadOnly)
throw new ReadOnlyBufferException();
return hb;
}
/**
* Returns the offset within this buffer's backing array of the first element of
* the buffer <i>(optional operation)</i>.
*
* <p>
* If this buffer is backed by an array then buffer position <i>p</i>
* corresponds to array index <i>p</i> + <tt>arrayOffset()</tt>.
*
* <p>
* Invoke the {@link #hasArray hasArray} method before invoking this method in
* order to ensure that this buffer has an accessible backing array.
* </p>
*
* @return 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-only
*
* @throws UnsupportedOperationException If this buffer is not backed by an
* accessible array
*/
public final int arrayOffset() {
if (hb == null)
throw new UnsupportedOperationException();
if (isReadOnly)
throw new ReadOnlyBufferException();
return offset;
}
/**
* Compacts this buffer <i>(optional operation)</i>.
*
* <p>
* 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
* <i>p</i> = <tt>position()</tt> is copied to index zero, the char at
* index <i>p</i> + 1 is copied to index one, and so forth until the
* char at index <tt>limit()</tt> - 1 is copied to index
* <i>n</i> = <tt>limit()</tt> - <tt>1</tt> - <i>p</i>.
* The buffer's position is then set to <i>n+1</i> and its limit is set to its
* capacity. The mark, if defined, is discarded.
*
* <p>
* 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 <i>put</i> method.
* </p>
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
* @return This buffer
*
* @throws ReadOnlyBufferException If this buffer is read-only
*/
public abstract CharBuffer compact();
/**
* Tells whether or not this char buffer is direct.
*
* @return <tt>true</tt> if, and only if, this buffer is direct
*/
public abstract boolean isDirect();
/**
* Returns the current hash code of this buffer.
*
* <p>
* The hash code of a char buffer depends only upon its remaining elements; that
* is, upon the elements from <tt>position()</tt> up to, and including, the
* element at <tt>limit()</tt> - <tt>1</tt>.
*
* <p>
* 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.
* </p>
*
* @return The current hash code of this buffer
*/
public int hashCode() {
int h = 1;
int p = position();
for (int i = limit() - 1; i >= p; i--)
h = 31 * h + (int) get(i);
return h;
}
/**
* Tells whether or not this buffer is equal to another object.
*
* <p>
* Two char buffers are equal if, and only if,
*
* <ol>
*
* <li>
* <p>
* They have the same element type,
* </p>
* </li>
*
* <li>
* <p>
* They have the same number of remaining elements, and
* </p>
* </li>
*
* <li>
* <p>
* The two sequences of remaining elements, considered independently of their
* starting positions, are pointwise equal.
*
*
*
*
*
*
*
* </p>
* </li>
*
* </ol>
*
* <p>
* A char buffer is not equal to any other type of object.
* </p>
*
* @param ob The object to which this buffer is to be compared
*
* @return <tt>true</tt> if, and only if, this buffer is equal to the given
* object
*/
public boolean equals(Object ob) {
if (this == ob)
return true;
if (!(ob instanceof CharBuffer))
return false;
CharBuffer that = (CharBuffer) ob;
if (this.remaining() != that.remaining())
return false;
int p = this.position();
for (int i = this.limit() - 1, j = that.limit() - 1; i >= p; i--, j--)
if (!equals(this.get(i), that.get(j)))
return false;
return true;
}
private static boolean equals(char x, char y) {
return x == y;
}
/**
* Compares this buffer to another.
*
* <p>
* 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 {@code char} elements are compared as if by invoking
* {@link Character#compare(char,char)}.
*
*
* <p>
* A char buffer is not comparable to any other type of object.
*
* @return A negative integer, zero, or a positive integer as this buffer is
* less than, equal to, or greater than the given buffer
*/
public int compareTo(CharBuffer that) {
int n = this.position() + Math.min(this.remaining(), that.remaining());
for (int i = this.position(), j = that.position(); i < n; i++, j++) {
int cmp = compare(this.get(i), that.get(j));
if (cmp != 0)
return cmp;
}
return this.remaining() - that.remaining();
}
private static int compare(char x, char y) {
return Character.compare(x, y);
}
方法2個toString,length,charAt,subSequence,3個append,order,chars
// -- Other char stuff --
/**
* 傳回包含此緩沖區中的字元的字元串。
*
* <p>
* 結果字元串的第一個字元将是這個緩沖區position的字元，
* 而最後一個字元将是索引limit() - 1處的字元。
* 調用此方法不會改變緩沖區的位置。
* </p>
*
* @return The specified string
*/
public String toString() {
return toString(position(), limit());
}
abstract String toString(int start, int end); // package-private
// --- 支援 CharSequence 的方法---
/**
* 傳回這個字元緩沖區的長度。
*
* <p>
* 當被看作一個字元序列時，字元緩沖區的長度就是position(包含)
* 和limit(排除)之間的字元數;
* 也就是說，它等價于remaining()。
* </p>
*
* @return The length of this character buffer
*/
public final int length() {
return remaining();
}
/**
* 讀取給定索引處相對于目前位置的字元。
*
* @param index The index of the character to be read, relative to the position;
* must be non-negative and smaller than <tt>remaining()</tt>
*
* @return The character at index <tt>position() + index</tt>
*
* @throws IndexOutOfBoundsException If the preconditions on <tt>index</tt> do
* not hold
*/
public final char charAt(int index) {
return get(position() + checkIndex(index, 1));
}
/**
* 建立一個新的字元緩沖區，表示該緩沖區相對于目前位置的指定子序列。
*
* <p>
* 新的緩沖區将共享該緩沖區的内容;
* 也就是說，如果這個緩沖區的内容是可變的，那麼對一個緩沖區的修改将導緻對另一個緩沖區的修改。
* 新緩沖區的容量就是這個緩沖區的容量，它的position是position() + start，它的limit是position() + end。
* 當且僅當此緩沖區是直接的，且僅當此緩沖區是隻讀的時，新緩沖區将是直接的，
* 且僅當此緩沖區是隻讀的時，且僅當此緩沖區是隻讀的時，新緩沖區将是直接的。
* </p>
*
* @param start The index, relative to the current position, of the first
* character in the subsequence; must be non-negative and no larger
* than <tt>remaining()</tt>
*
* @param end The index, relative to the current position, of the character
* following the last character in the subsequence; must be no
* smaller than <tt>start</tt> and no larger than
* <tt>remaining()</tt>
*
* @return The new character buffer
*
* @throws IndexOutOfBoundsException If the preconditions on <tt>start</tt> and
* <tt>end</tt> do not hold
*/
public abstract CharBuffer subSequence(int start, int end);
// --- Methods to support Appendable ---
/**
* Appends the specified character sequence to this
* buffer <i>(optional operation)</i>.
*
* <p>
* An invocation of this method of the form <tt>dst.append(csq)</tt> behaves in
* exactly the same way as the invocation
*
* <pre>
* dst.put(csq.toString())
* </pre>
*
* <p>
* Depending on the specification of <tt>toString</tt> for the character
* sequence <tt>csq</tt>, the entire sequence may not be appended. For instance,
* invoking the {@link CharBuffer#toString() toString} method of a character
* buffer will return a subsequence whose content depends upon the buffer's
* position and limit.
*
* @param csq The character sequence to append. If <tt>csq</tt> is
* <tt>null</tt>, then the four characters <tt>"null"</tt> are
* appended to this character buffer.
*
* @return This buffer
*
* @throws BufferOverflowException If there is insufficient space in this buffer
*
* @throws ReadOnlyBufferException If this buffer is read-only
*
* @since 1.5
*/
public CharBuffer append(CharSequence csq) {
if (csq == null)
return put("null");
else
return put(csq.toString());
}
/**
* Appends a subsequence of the specified character sequence to this
* buffer <i>(optional operation)</i>.
*
* <p>
* An invocation of this method of the form <tt>dst.append(csq, start,
* end)</tt> when <tt>csq</tt> is not <tt>null</tt>, behaves in exactly the same
* way as the invocation
*
* <pre>
* dst.put(csq.subSequence(start, end).toString())
* </pre>
*
* @param csq The character sequence from which a subsequence will be appended.
* If <tt>csq</tt> is <tt>null</tt>, then characters will be appended
* as if <tt>csq</tt> contained the four characters <tt>"null"</tt>.
*
* @return This buffer
*
* @throws BufferOverflowException If there is insufficient space in this
* buffer
*
* @throws IndexOutOfBoundsException If <tt>start</tt> or <tt>end</tt> are
* negative, <tt>start</tt> is greater than
* <tt>end</tt>, or <tt>end</tt> is greater
* than <tt>csq.length()</tt>
*
* @throws ReadOnlyBufferException If this buffer is read-only
*
* @since 1.5
*/
public CharBuffer append(CharSequence csq, int start, int end) {
CharSequence cs = (csq == null ? "null" : csq);
return put(cs.subSequence(start, end).toString());
}
/**
* Appends the specified char to this buffer <i>(optional
* operation)</i>.
*
* <p>
* An invocation of this method of the form <tt>dst.append(c)</tt> behaves in
* exactly the same way as the invocation
*
* <pre>
* dst.put(c)
* </pre>
*
* @param c The 16-bit char to append
*
* @return This buffer
*
* @throws BufferOverflowException If there is insufficient space in this buffer
*
* @throws ReadOnlyBufferException If this buffer is read-only
*
* @since 1.5
*/
public CharBuffer append(char c) {
return put(c);
}
// -- Other byte stuff: Access to binary data --
/**
* 檢索該緩沖區的位元組順序。
*
* <p>
* 通過配置設定或包裝現有的char數組建立的char緩沖區的位元組順序是底層硬體的ByteOrder.nativeOrder。
* 作為一個位元組緩沖區的視圖建立的char緩沖區的位元組順序
* 就是在視圖被建立時的位元組緩沖區的位元組順序。
* </p>
*
* @return This buffer's byte order
*/
public abstract ByteOrder order();
@Override
public IntStream chars() {
return StreamSupport.intStream(() -> new CharBufferSpliterator(this), Buffer.SPLITERATOR_CHARACTERISTICS,
false);
}