Java 中的 ByteBuffer asDoubleBuffer()方法，带示例
原文:https://www . geeksforgeeks . org/bytebuffer-as double buffer-in-Java-method-with-examples/
java.nio.ByteBuffer 类的 asDoubleBuffer() 方法用于创建该字节缓冲区作为双缓冲区的视图。 新缓冲区的内容将从该缓冲区的当前位置开始。对此缓冲区内容所做的更改将在新缓冲区中可见，反之亦然；两个缓冲器的位置、极限和标记值将是独立的。
新缓冲区的位置将为零，其容量和限制将是该缓冲区中剩余的字节数除以 8，其标记将是未定义的。如果且仅当该缓冲区是直接的，则新缓冲区将是直接的；如果且仅当该缓冲区是只读的，则新缓冲区将是只读的。
语法:
public abstract DoubleBuffer asDoubleBuffer()
返回值:这个方法返回一个新的双缓冲区。
以下是说明 asDoubleBuffer()方法的示例:
实施例 1:
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to demonstrate
// asDoubleBuffer() method
// for ByteBuffer
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 50;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// changing bytebuffer into
// DoubleBuffer
DoubleBuffer cb = bb.asDoubleBuffer();
// putting the value in DoubleBuffer
cb.put(5001.99);
cb.put(5002.99);
cb.put(5003.99);
cb.rewind();
// Declaring variable c
double c;
// print the ByteBuffer
System.out.print("DoubleBuffer : ");
while ((c = cb.get()) != 0)
System.out.print(c + " ");
}
catch (IllegalArgumentException e) {
System.out.println("Exception thrown : " + e);
}
catch (ReadOnlyBufferException e) {
System.out.println("Exception thrown : " + e);
}
}
}
Output:
DoubleBuffer : 5001.99 5002.99 5003.99
实施例 2:
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to demonstrate
// asDoubleBuffer() method
// for ByteBuffer
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 50;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// changing bytebuffer into
// DoubleBuffer
DoubleBuffer cb = bb.asDoubleBuffer();
// putting the value in DoubleBuffer
cb.put(5001.99);
cb.put(5002.99);
cb.put(5003.99);
cb.rewind();
// Declaring variable c
double c;
// print the ByteBuffer
System.out.print("DoubleBuffer : ");
while ((c = cb.get()) != 0)
System.out.print(c + " ");
// Creating a read-only copy of ByteBuffer
// using asReadOnlyBuffer() method
ByteBuffer bb1 = bb.asReadOnlyBuffer();
// changing read-only bytebuffer into
// read-only DoubleBuffer
DoubleBuffer cb1 = bb1.asDoubleBuffer();
// putting the value in read-only double buffer
System.out.println("\n\nTrying to put the value "
+ "in read only double buffer");
cb1.put(5001.99);
cb1.put(5002.99);
cb1.put(5003.99);
cb1.rewind();
}
catch (IllegalArgumentException e) {
System.out.println("Exception thrown : " + e);
}
catch (ReadOnlyBufferException e) {
System.out.println("Exception thrown : " + e);
}
}
}
Output:
DoubleBuffer : 5001.99 5002.99 5003.99
Trying to put the value in read only double buffer
Exception thrown : java.nio.ReadOnlyBufferException
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