极客教程Java ByteBuffer putFloat()方法及示例
putFloat(float value)
java.nio.ByteBuffer 类的 putFloat(float value) 方法用于将包含给定的浮点数值的四个字节，按照当前的字节顺序，写到这个缓冲区的当前位置，然后将位置递增四个。 语法
public abstract ByteBuffer putFloat(float value)
参数： 该方法接收一个参数 float值 ，即要写入的浮点数。
返回值： 该方法返回这个ByteBuffer，并将写入的浮点数作为参数传递。
异常： 该方法抛出以下异常。
- 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putFloat(float value)方法的例子：
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 ]
例2： 为了证明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
实例3： 为了证明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(int index, float value)
java.nio.ByteBuffer类的putFloat(int index, float value)方法用于将包含给定的4个字节的值，按照当前的字节顺序，在给定的索引处写入这个缓冲区。
语法
public abstract ByteBuffer putFloat(int index, float 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putFloat(int index, float value)方法的例子：
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 ]
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
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
参考资料
- 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-