Java中的 ByteBuffer putFloat() 方法及示例
putFloat（浮点值）
Java.nio.ByteBuffer类的putFloat(float value)方法用于将包含给定浮点值的四个字节以当前字节顺序写入该缓冲区的当前位置，然后将该位置增加四。
句法：
public abstract ByteBuffer putFloat(float value)参数：此方法采用参数浮点值，即要写入的浮点值。
返回值：此方法返回此 ByteBuffer，并将写入的浮点值作为参数传递。
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
以下是说明 putFloat(float value) 方法的示例：
示例 1：
// Java program to demonstrate
// putFloat() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 12;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting the value in ByteBuffer
// using putFloat() method
bb.putFloat(23.4f)
.putFloat(234.5f)
.putFloat(34.56f)
.rewind();
// print the ByteBuffer
System.out.print("Original ByteBuffer: [ ");
for (int i = 1; i <= capacity / 4; i++)
System.out.print(bb.getFloat() + " ");
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
// putFloat() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 12;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting the value in ByteBuffer
// using putFloat() method
bb.putFloat(23.4f)
.putFloat(234.5f)
.putFloat(34.56f)
.rewind();
// print the ByteBuffer
System.out.print("Original ByteBuffer: [ ");
for (int i = 1; i <= capacity / 4; i++)
System.out.print(bb.getFloat() + " ");
System.out.print("]");
// putting the value in ByteBuffer
// using putFloat() method
bb.putFloat(234.55f);
}
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
// putFloat() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 12;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting the value in ByteBuffer
// using putFloat() method
bb.putFloat(23.4f)
.putFloat(234.5f)
.putFloat(34.56f)
.rewind();
// print the ByteBuffer
System.out.print("Original ByteBuffer: [ ");
for (int i = 1; i <= capacity / 4; i++)
System.out.print(bb.getFloat() + " ");
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 float value"
+ " in read-only buffer");
// putting the value in readonly ByteBuffer
// using putFloat() method
bb1.putFloat(234.5f);
}
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 float value in read-only buffer
Exception throws : java.nio.ReadOnlyBufferException
putFloat（整数索引，浮点值）
Java.nio.ByteBuffer 类的 putFloat(int index, float value) 方法用于将包含给定四个值的四个字节以当前字节顺序写入到给定索引处的此缓冲区中。
句法：
public abstract ByteBuffer putFloat(int index, float 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 putFloat(int index, float value) 方法的示例：
示例 1：
// Java program to demonstrate
// putFloat() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 12;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting the value in ByteBuffer
// using putFloat() at index 0
bb.putFloat(0, 23.45f);
// putting the value in ByteBuffer
// using putFloat() at index 4
bb.putFloat(4, 34.56f);
// putting the value in ByteBuffer
// using putFloat() at index 8
bb.putFloat(8, 27.56f);
// rewinding the ByteBuffer
bb.rewind();
// print the ByteBuffer
System.out.print("Original ByteBuffer: [ ");
for (int i = 1; i <= capacity / 4; i++)
System.out.print(bb.getFloat() + " ");
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
// putFloat() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 12;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting the value in ByteBuffer
// using putFloat() at index 0
bb.putFloat(0, 23.45f);
// putting the value in ByteBuffer
// using putFloat() at index 4
bb.putFloat(4, 34.56f);
// putting the value in ByteBuffer
// using putFloat() at index 8
bb.putFloat(8, 27.56f);
// rewinding the ByteBuffer
bb.rewind();
// print the ByteBuffer
System.out.print("Original ByteBuffer: [ ");
for (int i = 1; i <= capacity / 4; i++)
System.out.print(bb.getFloat() + " ");
System.out.print("]\n");
// putting the value in ByteBuffer
// using putFloat() at index -1
bb.putFloat(-1, 45.67f);
}
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
// putFloat() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 12;
// 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 float value"
+ " in read only buffer");
// putting the value in readonly ByteBuffer
// using putFloat() method
bb1.putFloat(0, 23.4f);
}
catch (IndexOutOfBoundsException e) {
System.out.println("Exception throws : " + e);
}
catch (ReadOnlyBufferException e) {
System.out.println("Exception throws : " + e);
}
}
}
输出：
Trying to put the float value in read only buffer
Exception throws : java.nio.ReadOnlyBufferException
参考：
- https://docs.oracle.com/javase/9/docs/api/ Java/nio/ByteBuffer.html#putFloat-float-
- https://docs.oracle.com/javase/9/docs/api/ Java/nio/ByteBuffer.html#getFloat-int-