极客教程Java ByteBuffer putChar()方法及实例
putChar(char value)
java.nio.ByteBuffer 类的 putChar(char value) 方法用于将包含给定char值的两个字节，按照当前的字节顺序，写到这个缓冲区的当前位置，然后将位置递增2。
语法
public abstract ByteBuffer putChar(char value)
参数： 该方法接收要写入的char值。
返回值： 该方法返回这个缓冲区。
异常： 该方法会抛出以下异常。
- BufferOverflowException- 如果这个缓冲区的当前位置不小于它的极限值。
- ReadOnlyBufferException- 如果这个缓冲区是只读的。
下面是说明putChar(char value)方法的例子。
例子1 :
// Java program to demonstrate
// putChar() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 6;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting the value in ByteBuffer
// using putChar() method
bb.putChar('a')
.putChar('b')
.putChar('c')
.rewind();
// print the ByteBuffer
System.out.print("Original ByteBuffer: [ ");
for (int i = 1; i <= capacity / 2; i++)
System.out.print(bb.getChar() + " ");
System.out.print("]");
}
catch (BufferOverflowException e) {
System.out.println("Exception throws : " + e);
}
catch (ReadOnlyBufferException e) {
System.out.println("Exception throws : " + e);
}
}
}
输出。
Original ByteBuffer: [ a b c ]
例2： 为了证明BufferOverflowException。
// Java program to demonstrate
// putChar() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 6;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting the value in ByteBuffer
// using putChar() method
bb.putChar('a')
.putChar('b')
.putChar('c')
.rewind();
// print the ByteBuffer
System.out.print("Original ByteBuffer: [ ");
for (int i = 1; i <= capacity / 2; i++)
System.out.print(bb.getChar() + " ");
System.out.print("]\n\n");
// putting the value in ByteBuffer
// using putChar() method
bb.putChar('d');
}
catch (BufferOverflowException e) {
System.out.println("buffer's current position"
+ " is not smaller than"
+ " its limit");
System.out.println("Exception throws : " + e);
}
catch (ReadOnlyBufferException e) {
System.out.println("Exception throws : " + e);
}
}
}
输出。
Original ByteBuffer: [ a b c ]
buffer's current position is not smaller than its limit
Exception throws : java.nio.BufferOverflowException
实例3： 为了证明ReadOnlyBufferException。
// Java program to demonstrate
// putChar() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 6;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting the value in ByteBuffer
// using putChar() method
bb.putChar('a')
.putChar('b')
.putChar('c')
.rewind();
// print the ByteBuffer
System.out.print("Original ByteBuffer: [ ");
for (int i = 1; i <= capacity / 2; i++)
System.out.print(bb.getChar() + " ");
System.out.print("]\n");
// Creating a read-only copy of ByteBuffer
// using asReadOnlyBuffer() method
ByteBuffer bb1 = bb.asReadOnlyBuffer();
System.out.println("\nTrying to put the char value"
+ " in read-only buffer");
// putting the value in readonly ByteBuffer
// using putChart() method
bb1.putChar('d');
}
catch (BufferOverflowException e) {
System.out.println("Exception throws : " + e);
}
catch (ReadOnlyBufferException e) {
System.out.println("Exception throws : " + e);
}
}
}
输出。
Original ByteBuffer: [ a b c ]
Trying to put the char value in read-only buffer
Exception throws : java.nio.ReadOnlyBufferException
putChar(int index, char value)
java.nio.ByteBuffer类的putChar(int index, char value)方法用于将包含给定的char值的两个字节，按照当前的字节顺序，写到这个缓冲区的给定索引处。
语法
public abstract ByteBuffer putChar(int index, char value)
参数： 该方法接受以下参数作为参数。
- index : 将被写入的字节的索引
- value : 要写入的字符值
返回值 ：该方法返回这个缓冲区。
异常： 该方法会抛出以下异常。
- IndexOutOfBoundsException- 如果索引是负数或者不小于缓冲区的极限值。
- ReadOnlyBufferException- 如果这个缓冲区是只读的。
下面是说明putChar(int index, char value)方法的例子。
例子1 :
// Java program to demonstrate
// putChar() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 6;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting the value in ByteBuffer
// using putChar() at index 0
bb.putChar(0, 'a');
// putting the value in ByteBuffer
// using putChar() at index 2
bb.putChar(2, 'b');
// putting the value in ByteBuffer
// using putChar() at index 1
bb.putChar(4, 'c');
// rewinding the ByteBuffer
bb.rewind();
// print the ByteBuffer
System.out.print("Original ByteBuffer: [ ");
for (int i = 1; i <= capacity / 2; i++)
System.out.print(bb.getChar() + " ");
System.out.print("]\n");
}
catch (IndexOutOfBoundsException e) {
System.out.println("Exception throws : " + e);
}
catch (ReadOnlyBufferException e) {
System.out.println("Exception throws : " + e);
}
}
}
输出。
Original ByteBuffer: [ a b c ]
例2： 演示IndexOutOfBoundsException。
// Java program to demonstrate
// putChar() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 6;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting the value in ByteBuffer
// using putChar() at index 0
bb.putChar(0, 'a');
// putting the value in ByteBuffer
// using putChar() at index 2
bb.putChar(2, 'b');
// putting the value in ByteBuffer
// using putChar() at index 1
bb.putChar(4, 'c');
// rewinding the ByteBuffer
bb.rewind();
// print the ByteBuffer
System.out.print("Original ByteBuffer: [ ");
for (int i = 1; i <= capacity / 2; i++)
System.out.print(bb.getChar() + " ");
System.out.print("]\n");
// putting the value in ByteBuffer
// using put() at index -1
bb.putChar(-1, 'd');
}
catch (IndexOutOfBoundsException e) {
System.out.println("\nindex is negative or not smaller "
+ "than the buffer's limit");
System.out.println("Exception throws : " + e);
}
catch (ReadOnlyBufferException e) {
System.out.println("Exception throws : " + e);
}
}
}
输出。
Original ByteBuffer: [ a b c ]
index is negative or not smaller than the buffer's limit
Exception throws : java.lang.IndexOutOfBoundsException
例3： 演示ReadOnlyBufferException。
// Java program to demonstrate
// putChar() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 6;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// Creating a read-only copy of ByteBuffer
// using asReadOnlyBuffer() method
ByteBuffer bb1 = bb.asReadOnlyBuffer();
System.out.println("Trying to put the byte value"
+ " in read-only buffer");
// putting the value in readonly ByteBuffer
// using putChar() method
bb1.putChar(4, 'c');
}
catch (IndexOutOfBoundsException e) {
System.out.println("Exception throws : " + e);
}
catch (ReadOnlyBufferException e) {
System.out.println("Exception throws : " + e);
}
}
}
输出。
Trying to put the byte value in read-only buffer
Exception throws : java.nio.ReadOnlyBufferException
参考资料
- https://docs.oracle.com/javase/9/docs/api/java/nio/ByteBuffer.html#putChar-char-
- https://docs.oracle.com/javase/9/docs/api/java/nio/ByteBuffer.html#putChar-int-char-