Java中的 ByteBuffer get() 方法及示例
得到（）
Java.nio.ByteBuffer类的get()方法用于读取缓冲区当前位置的字节，然后递增该位置。
句法 ：
public abstract byte get()返回值：此方法返回缓冲区当前位置的字节。
抛出：此方法抛出BufferUnderflowException – 如果缓冲区的当前位置不小于其限制，则抛出此异常。
以下是说明get()方法的示例：
示例 1：
// Java program to demonstrate
// get() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 5;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting the int to byte value in ByteBuffer
bb.put((byte)20);
bb.put((byte)30);
bb.put((byte)40);
bb.rewind();
// print the ByteBuffer
System.out.println("Original ByteBuffer: "
+ Arrays.toString(bb.array()));
// Reads the byte at this buffer's current position
// using get() method
byte value = bb.get();
// print the byte value
System.out.println("\nByte Value: " + value);
// Reads the Byte at this buffer's next position
// using get() method
byte value1 = bb.get();
// print the Float value
System.out.print("\nNext Byte Value: " + value1);
}
catch (IllegalArgumentException e) {
System.out.println("\nException Thrown : " + e);
}
catch (ReadOnlyBufferException e) {
System.out.println("\nException Thrown : " + e);
}
catch (BufferUnderflowException e) {
System.out.println("\nException Thrown : " + e);
}
}
}
输出：
Original ByteBuffer: [20, 30, 40, 0, 0]
Byte Value: 20
Next Byte Value: 30
示例 2：
// Java program to demonstrate
// get() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 3;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting the int to byte typecast value in ByteBuffer
bb.put((byte)20);
bb.put((byte)30);
// print the ByteBuffer
System.out.println("Original ByteBuffer: "
+ Arrays.toString(bb.array()));
// Reads the byte at this buffer's current position
// using get() method
byte value = bb.get();
// print the byte value
System.out.println("\nByte Value: " + value);
// Reads the Byte at this buffer's next position
// using get() method
System.out.print("\nsince the buffer current position is incremented");
System.out.print(" to greater than its limit ");
byte value1 = bb.get();
// print the Byte value
System.out.print("\nNext Byte Value: " + value1);
}
catch (IllegalArgumentException e) {
System.out.println("\nIllegalArgumentException catched");
}
catch (ReadOnlyBufferException e) {
System.out.println("\nReadOnlyBufferException catched");
}
catch (BufferUnderflowException e) {
System.out.println("\nException throws : " + e);
}
}
}
输出：
Original ByteBuffer: [20, 30, 0]
Byte Value: 0
since the buffer current position is incremented to greater than its limit
Exception throws : java.nio.BufferUnderflowException
获取（整数索引）
ByteBuffer 的 get(int index) 方法用于读取指定索引处的文章。
句法 ：
public abstract byte get(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字节值。
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get(int index)方法的示例：
示例 1：
// Java program to demonstrate
// get(int index) method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 3;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting the int to byte typecast value in ByteBuffer
bb.put((byte)20);
bb.put((byte)30);
bb.put((byte)40);
// print the ByteBuffer
System.out.println("Original ByteBuffer: "
+ Arrays.toString(bb.array()));
// Reads the Byte at the index 0 of the Bytebuffer
// using get() method
byte value0 = bb.get(0);
// print the Byte value
System.out.println("\nByte Value at index 0: " + value0);
// Reads the Byte at the index 1 of the Bytebuffer
// using get() method
byte value1 = bb.get(1);
// print the Byte value
System.out.println("\nByte Value at index 1: " + value1);
// Reads the Byte at the index 2 of the Bytebuffer
// using get() method
byte value2 = bb.get(2);
// print the Byte value
System.out.println("\nByte Value at index 2: " + value2);
}
catch (IllegalArgumentException e) {
System.out.println("\nIllegalArgumentException catched");
}
catch (IndexOutOfBoundsException e) {
System.out.println("\nReadOnlyBufferException catched");
}
catch (BufferUnderflowException e) {
System.out.println("\nException throws : " + e);
}
}
}
输出：
Original ByteBuffer: [20, 30, 40]
Byte Value at index 0: 20
Byte Value at index 1: 30
Byte Value at index 2: 40
示例 2：
// Java program to demonstrate
// get(int index) method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 3;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting the int to byte typecast value in ByteBuffer
bb.put((byte)20);
bb.put((byte)30);
bb.put((byte)40);
// print the ByteBuffer
System.out.println("Original ByteBuffer: "
+ Arrays.toString(bb.array()));
// Reads the Byte at the index 0 of the Bytebuffer
// using get() method
byte value0 = bb.get(0);
// print the Byte value
System.out.println("\nByte Value at index 0: " + value0);
// Reads the Byte at the index 1 of the Bytebuffer
// using get() method
byte value1 = bb.get(1);
// print the Byte value
System.out.println("\nByte Value at index 1: " + value1);
// Reads the Byte at the index 4 of the Bytebuffer
// using get() method
System.out.println("\nTrying to get the byte"
+ " of index greater than its limit ");
byte value2 = bb.get(4);
// print the Byte value
System.out.println("\nByte Value at index 4: " + value2);
}
catch (IndexOutOfBoundsException e) {
System.out.println("\nException throws : " + e);
}
catch (BufferUnderflowException e) {
System.out.println("\nException throws : " + e);
}
}
}
输出：
Original ByteBuffer: [20, 30, 40]
Byte Value at index 0: 20
Byte Value at index 1: 30
Trying to get the byte of index greater than its limit
Exception throws : java.lang.IndexOutOfBoundsException