Java中的 ByteBuffer putDouble() 方法及示例
putDouble（双值）
Java.nio.ByteBuffer类的putDouble(double value)方法用于将包含给定 double 值的 8 个字节以当前字节顺序写入该缓冲区的当前位置，然后将该位置增加 8。
句法：
public abstract ByteBuffer putDouble?(double value)参数：此方法采用要写入的双精度值。
返回值：此方法返回此缓冲区。
异常：此方法抛出以下异常：
- BufferOverflowException-如果此缓冲区的当前位置不小于其限制
- ReadOnlyBufferException-如果此缓冲区是只读的
下面是说明 putDouble(double value) 方法的示例：
示例 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 ]
示例 2：演示 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
示例 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 = 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（整数索引，双精度值）
Java.nio.ByteBuffer 类的 putDouble(int index, double value) 方法用于将包含给定 double 值的 8 个字节以当前字节顺序写入该缓冲区中给定索引处。
句法：
public abstract ByteBuffer putDouble(int index, double value)参数：此方法采用以下参数作为参数：
- index ：将写入字节的索引
- value : 要写入的 double 值
返回值：此方法返回此缓冲区。
异常：此方法抛出以下异常：
- IndexOutOfBoundsException-如果 index 为负数或不小于缓冲区的限制
- ReadOnlyBufferException-如果此缓冲区是只读的
以下是说明 put(int index, double value) 方法的示例：
示例 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 ]
示例 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
示例 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：
- 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-