Java中的 ByteBuffer getInt() 方法及示例
获取整数（）
Java.nio.ByteBuffer类的getInt()方法用于读取该缓冲区当前位置接下来的四个字节，按照当前字节顺序将它们组合成一个int值，然后将该位置加四。
句法：
public abstract int getInt()返回值：该方法返回缓冲区当前位置的 int 值
抛出：此方法抛出BufferUnderflowException – 如果此缓冲区中剩余的字节少于四个。
以下是说明 getInt() 方法的示例：
示例 1：
// Java program to demonstrate
// getInt() 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 int value in the bytebuffer
bb.asIntBuffer()
.put(10)
.put(20)
.put(30);
// rewind the Bytebuffer
bb.rewind();
// print the ByteBuffer
System.out.println("Original ByteBuffer: ");
for (int i = 1; i <= capacity / 4; i++)
System.out.print(bb.getInt() + " ");
// rewind the Bytebuffer
bb.rewind();
// Reads the Int at this buffer's current position
// using getInt() method
int value = bb.getInt();
// print the int value
System.out.println("\n\nByte Value: " + value);
// Reads the int at this buffer's next position
// using getInt() method
int value1 = bb.getInt();
// print the int value
System.out.println("Next Byte Value: " + value1);
}
catch (BufferUnderflowException e) {
System.out.println("\nException Thrown : " + e);
}
}
}
输出：
Original ByteBuffer:
10 20 30
Byte Value: 10
Next Byte Value: 20
示例 2：
// Java program to demonstrate
// getInt() 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);
// putting the int value in the bytebuffer
bb.asIntBuffer()
.put(10)
.put(20);
// rewind the Bytebuffer
bb.rewind();
// print the ByteBuffer
System.out.println("Original ByteBuffer: ");
for (int i = 1; i <= capacity / 4; i++)
System.out.print(bb.getInt() + " ");
// rewind the Bytebuffer
bb.rewind();
// Reads the Int at this buffer's current position
// using getInt() method
int value = bb.getInt();
// print the int value
System.out.println("\n\nByte Value: " + value);
// Reads the int at this buffer's next position
// using getInt() method
int value1 = bb.getInt();
// print the int value
System.out.println("Next Byte Value: " + value1);
// Reads the int at this buffer's next position
// using getInt() method
int value2 = bb.getInt();
}
catch (BufferUnderflowException e) {
System.out.println("\nthere are fewer than "
+ "four bytes remaining in this buffer");
System.out.println("Exception Thrown : " + e);
}
}
}
输出：
Original ByteBuffer:
10 20
Byte Value: 10
Next Byte Value: 20
there are fewer than four bytes remaining in this buffer
Exception Thrown : java.nio.BufferUnderflowException
参考： https://docs.oracle.com/javase/9/docs/api/ Java/nio/ByteBuffer.html#getInt–
getInt（整数索引）
ByteBuffer的getInt(int index)方法用于读取给定索引处的四个字节，根据当前字节顺序将它们组合成一个 int 值。
句法 ：
public abstract int getInt(int index)参数：此方法以索引（将从中读取字节的索引）作为参数。
返回值：此方法返回给定索引处的 int 值。
异常：此方法抛出IndexOutOfBoundsException 。如果 index 为负数或不小于缓冲区的限制，则会引发此异常。
以下是说明getInt(int index)方法的示例：
示例 1：
// Java program to demonstrate
// getInt() 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);
// putting the int value in the bytebuffer
bb.asIntBuffer()
.put(10)
.put(20);
// rewind the Bytebuffer
bb.rewind();
// print the ByteBuffer
System.out.println("Original ByteBuffer: ");
for (int i = 1; i <= capacity / 4; i++)
System.out.print(bb.getInt() + " ");
// rewind the Bytebuffer
bb.rewind();
// Reads the Int at this buffer's current position
// using getInt() method
int value = bb.getInt(0);
// print the int value
System.out.println("\n\nByte Value: " + value);
// Reads the int at this buffer's next position
// using getInt() method
int value1 = bb.getInt(4);
// print the int value
System.out.println("Next 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:
10 20
Byte Value: 10
Next Byte Value: 20
示例 2：
// Java program to demonstrate
// getInt() 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);
// putting the int value in the bytebuffer
bb.asIntBuffer()
.put(10)
.put(20);
// rewind the Bytebuffer
bb.rewind();
// print the ByteBuffer
System.out.println("Original ByteBuffer: ");
for (int i = 1; i <= capacity / 4; i++)
System.out.print(bb.getInt() + " ");
// rewind the Bytebuffer
bb.rewind();
// Reads the Int at this buffer's current position
// using getInt() method
int value = bb.getInt(0);
// print the int value
System.out.println("\n\nByte Value: " + value);
// Reads the int at this buffer's next position
// using getInt() method
int value1 = bb.getInt(7);
// print the int value
System.out.println("Next 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:
10 20
Byte Value: 10
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#getInt-int-