极客教程Java ByteBuffer putDouble()方法及示例
putDouble(double value)
java.nio.ByteBuffer 类的 putDouble(double value) 方法用于将包含给定的双倍值的8个字节，按照当前的字节顺序，写到这个缓冲区的当前位置，然后将这个位置增加8。
语法
public abstract ByteBuffer putDouble?(double value)
参数： 此方法接收要写入的双倍值。
返回值： 此方法返回此缓冲区。
异常： 此方法抛出以下异常。
- 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putDouble(double value)方法的例子：
例1 :
// Java program to demonstrate
// putDouble() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 24;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting the value in ByteBuffer
// using putDouble() method
bb.putDouble(23.4)
.putDouble(234.5)
.putDouble(34.56)
.rewind();
// print the ByteBuffer
System.out.print("Original ByteBuffer: [ ");
for (int i = 1; i <= capacity / 8; i++)
System.out.print(bb.getDouble() + " ");
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: [ 23.4 234.5 34.56 ]
例2： 为了证明BufferOverflowException。
// Java program to demonstrate
// putDouble() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 24;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting the value in ByteBuffer
// using putDouble() method
bb.putDouble(23.4)
.putDouble(234.5)
.putDouble(34.56)
.rewind();
// print the ByteBuffer
System.out.print("Original ByteBuffer: [ ");
for (int i = 1; i <= capacity / 8; i++)
System.out.print(bb.getDouble() + " ");
System.out.print("]");
// putting the value in ByteBuffer
// using putDouble() method
bb.putDouble(234.55);
}
catch (BufferOverflowException e) {
System.out.println("\n\nbuffer'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: [ 23.4 234.5 34.56 ]
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
// putDouble() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 24;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting the value in ByteBuffer
// using putDouble() method
bb.putDouble(23.4)
.putDouble(234.5)
.putDouble(34.56)
.rewind();
// print the ByteBuffer
System.out.print("Original ByteBuffer: [ ");
for (int i = 1; i <= capacity / 8; i++)
System.out.print(bb.getDouble() + " ");
System.out.print("]");
// Creating a read-only copy of ByteBuffer
// using asReadOnlyBuffer() method
ByteBuffer bb1 = bb.asReadOnlyBuffer();
System.out.println("\n\nTrying to put the char value"
+ " in read-only buffer");
// putting the value in readonly ByteBuffer
// using putDouble() method
bb1.putDouble(234.5);
}
catch (BufferOverflowException e) {
System.out.println("Exception throws : " + e);
}
catch (ReadOnlyBufferException e) {
System.out.println("Exception throws : " + e);
}
}
}
输出
Original ByteBuffer: [ 23.4 234.5 34.56 ]
Trying to put the char value in read-only buffer
Exception throws : java.nio.ReadOnlyBufferException
putDouble(int index, double value)
java.nio.ByteBuffer类的putDouble(int index, double value)方法用于将包含给定的双倍值的8个字节，按照当前的字节顺序，在给定的索引处写入这个缓冲区中。 语法
public abstract ByteBuffer putDouble(int index, double value)
参数： 该方法接受以下参数作为参数。
- index : 将被写入字节的索引
- value : 将要写入的双倍值
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put(int index, double value)方法的例子：
例1 :
// Java program to demonstrate
// putDouble() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 24;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting the value in ByteBuffer
// using putDouble() at index 0
bb.putDouble(0, 23.45);
// putting the value in ByteBuffer
// using putDouble() at index 8
bb.putDouble(8, 34.56);
// putting the value in ByteBuffer
// using putDouble() at index 16
bb.putDouble(16, 27.56);
// rewinding the ByteBuffer
bb.rewind();
// print the ByteBuffer
System.out.print("Original ByteBuffer: [ ");
for (int i = 1; i <= capacity / 8; i++)
System.out.print(bb.getDouble() + " ");
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: [ 23.45 34.56 27.56 ]
例2： 演示IndexOutOfBoundsException。
// Java program to demonstrate
// putDouble() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 24;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting the value in ByteBuffer
// using putDouble() at index 0
bb.putDouble(0, 23.45);
// putting the value in ByteBuffer
// using putDouble() at index 8
bb.putDouble(8, 34.56);
// putting the value in ByteBuffer
// using putDouble() at index 16
bb.putDouble(16, 27.56);
// rewinding the ByteBuffer
bb.rewind();
// print the ByteBuffer
System.out.print("Original ByteBuffer: [ ");
for (int i = 1; i <= capacity / 8; i++)
System.out.print(bb.getDouble() + " ");
System.out.print("]\n");
// putting the value in ByteBuffer
// using putDouble() at index -1
bb.putDouble(-1, 45.67);
}
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: [ 23.45 34.56 27.56 ]
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
// putDouble() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 8;
// 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 putDouble() method
bb1.putDouble(0, 'a');
}
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#putDouble-double-
- https://docs.oracle.com/javase/9/docs/api/java/nio/ByteBuffer.html#putDouble-int-double-