Java 中的 ByteBuffer getDouble()方法，带示例
原文:https://www . geeksforgeeks . org/bytebuffer-get double-method-in-Java-with-examples/
getDouble()
Java . nio . bytebuffer类的 getDouble() 方法用于读取该缓冲区当前位置的下八个字节，按照当前字节顺序组成一个 Double 值，然后将该位置递增八。
语法:
public abstract double getDouble()
返回值:该方法返回缓冲区当前位置的双精度值
抛出:此方法抛出bufferenderflow exception如果缓冲区当前位置不小于其限制，则抛出此异常。
下面是说明 getDouble()方法的示例:
示例 1:
// Java program to demonstrate
// getDouble() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 16;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting the double value in the bytebuffer
bb.asDoubleBuffer()
.put(1234.3456)
.put(2884.4444);
// rewind the Bytebuffer
bb.rewind();
// print the ByteBuffer
System.out.println("Original ByteBuffer: ");
for (int i = 1; i <= capacity / 8; i++)
System.out.print(bb.getDouble() + " ");
// rewind the Bytebuffer
bb.rewind();
// Reads the double at this buffer's current position
// using getDouble() method
double value = bb.getDouble();
// print the char value
System.out.println("\n\nByte Value: " + value);
// Reads the char at this buffer's next position
// using getDouble() method
double value1 = bb.getDouble();
// print the char value
System.out.print("\nNext Byte Value: " + value1);
}
catch (BufferUnderflowException e) {
System.out.println("\nException Thrown : " + e);
}
}
}
输出:
Original ByteBuffer:
1234.3456 2884.4444
Byte Value: 1234.3456
Next Byte Value: 2884.4444
示例 2:
// Java program to demonstrate
// getDouble() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 16;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting the double value in the bytebuffer
bb.asDoubleBuffer()
.put(1234.3456)
.put(2884.4444);
// rewind the Bytebuffer
bb.rewind();
// print the ByteBuffer
System.out.println("Original ByteBuffer: ");
for (int i = 1; i <= capacity / 8; i++)
System.out.print(bb.getDouble() + " ");
// rewind the Bytebuffer
bb.rewind();
// Reads the double at this buffer's current position
// using getDouble() method
double value = bb.getDouble();
// print the char value
System.out.println("\n\nByte Value: " + value);
// Reads the char at this buffer's next position
// using getDouble() method
double value1 = bb.getDouble();
// print the char value
System.out.println("\nNext Byte Value: " + value1);
// Reads the char at this buffer's next position
// using getDouble() method
double value2 = bb.getDouble();
}
catch (BufferUnderflowException e) {
System.out.println("\nthere are fewer than "
+ "eight bytes remaining in"
+ " this buffer");
System.out.println("Exception Thrown : " + e);
}
}
}
输出:
Original ByteBuffer:
1234.3456 2884.4444
Byte Value: 1234.3456
Next Byte Value: 2884.4444
there are fewer than eight bytes remaining in this buffer
Exception Thrown : java.nio.BufferUnderflowException
参考:T2【https://docs . Oracle . com/javase/9/docs/API/Java/nio/bytebuffer . html # getDouble–T4getDouble(int index)T7】
字节缓冲的 getDouble(int index) 方法用于读取给定索引处的八个字节，根据当前字节顺序将它们组成一个双数值。
语法:
public abstract double getDouble(int index)
参数:该方法以索引为参数，该参数是读取字节的索引。
返回值:该方法返回给定索引处的双精度值
异常:此方法抛出indexout of boundsexception。如果索引为负或不小于缓冲区的限制，则会引发此异常。
下面是举例说明 getDouble(int index) 方法的例子:
示例 1:
// Java program to demonstrate
// getDouble() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 16;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting the double value in the bytebuffer
bb.asDoubleBuffer()
.put(1234.3456)
.put(2884.4444);
// rewind the Bytebuffer
bb.rewind();
// Declaring the variable
double c;
// print the ByteBuffer
System.out.println("Original ByteBuffer: ");
for (int i = 1; i <= capacity / 8; i++)
System.out.print(bb.getDouble() + " ");
// rewind the Bytebuffer
bb.rewind();
// Reads the double at this buffer's current position
// using getDouble() method
double value = bb.getDouble(0);
// print the char value
System.out.println("\n\nByte Value: " + value);
// Reads the char at this buffer's next position
// using getDouble() method
double value1 = bb.getDouble(8);
// print the char value
System.out.print("\nNext Byte Value: " + value1);
}
catch (IndexOutOfBoundsException e) {
System.out.println("\nindex is negative or "
+ "smaller than the buffer's "
+ "limit, minus seven");
System.out.println("Exception Thrown : " + e);
}
}
}
输出:
Original ByteBuffer:
1234.3456 2884.4444
Byte Value: 1234.3456
Next Byte Value: 2884.4444
示例 2:
// Java program to demonstrate
// getDouble() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 16;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting the double value in the bytebuffer
bb.asDoubleBuffer()
.put(1234.3456)
.put(2884.4444);
// rewind the Bytebuffer
bb.rewind();
// Declaring the variable
double c;
// print the ByteBuffer
System.out.println("Original ByteBuffer: ");
for (int i = 1; i <= capacity / 8; i++)
System.out.print(bb.getDouble() + " ");
// rewind the Bytebuffer
bb.rewind();
// Reads the double at this buffer's current position
// using getDouble() method
double value = bb.getDouble(0);
// print the char value
System.out.println("\n\nByte Value: " + value);
// Reads the char at this buffer's next position
// using getDouble() method
double value1 = bb.getDouble(9);
// print the char value
System.out.print("\nNext Byte Value: " + value1);
}
catch (IndexOutOfBoundsException e) {
System.out.println("\nindex is negative or"
+ " smaller than the buffer's"
+ " limit, minus seven");
System.out.println("Exception Thrown : " + e);
}
}
}
输出:
Original ByteBuffer:
1234.3456 2884.4444
Byte Value: 1234.3456
index is negative or smaller than the buffer's limit, minus seven
Exception Thrown : java.lang.IndexOutOfBoundsException
参考:https://docs . Oracle . com/javase/9/docs/API/Java/nio/bytebuffer . html # getDouble-int-
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