Java Buffer limit()用法及代码示例

java.nio.Buffer类的limit()方法用于设置此缓冲区的限制。如果位置大于新限制，则将其设置为新限制。如果标记已定义且大于新限制，则将其丢弃。

用法:

public Buffer limit(int newLimit)

返回值：此方法返回此缓冲区。

下面是说明limit()方法的示例：

范例1：

// Java program to demonstrate 
// limit() method 
  
import java.nio.*; 
import java.util.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
        // defining and allocating ByteBuffer 
        // using allocate() method 
        ByteBuffer byteBuffer 
            = ByteBuffer.allocate(4); 
  
        // put byte value in byteBuffer 
        // using put() method 
        byteBuffer.put((byte)20); 
        byteBuffer.put((byte)30); 
  
        // Typecast byteBuffer to buffer 
        Buffer buffer = (Buffer)byteBuffer; 
  
        // print the byte buffer 
        System.out.println("Buffer before operation:"
                           + Arrays.toString( 
                                 (byte[])buffer.array()) 
                           + "\nPosition:"
                           + buffer.position() 
                           + "\nLimit:"
                           + buffer.limit()); 
  
        // Limit the Buffer 
        // using limit() method 
        buffer.limit(1); 
  
        // print the buffer 
        System.out.println("\nBuffer after operation:"
                           + Arrays.toString( 
                                 (byte[])buffer.array()) 
                           + "\nPosition:"
                           + buffer.position() 
                           + "\nLimit:"
                           + buffer.limit()); 
    } 
}

输出：

Buffer before operation:[20, 30, 0, 0]
Position:2
Limit:4

Buffer after operation:[20, 30, 0, 0]
Position:1
Limit:1

范例2：

// Java program to demonstrate 
// limit() method 
  
import java.nio.*; 
import java.util.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
        // defining and allocating ByteBuffer 
        // using allocate() method 
        ByteBuffer byteBuffer 
            = ByteBuffer.allocate(5); 
  
        // put byte value in byteBuffer 
        // using put() method 
        byteBuffer.put((byte)20); 
        byteBuffer.put((byte)30); 
        byteBuffer.put((byte)40); 
  
        // Typecast byteBuffer to buffer 
        Buffer buffer = (Buffer)byteBuffer; 
  
        // mark will be going to discarded by limit() 
        buffer.mark(); 
  
        // print the buffer 
        System.out.println("Buffer before operation:"
                           + Arrays.toString( 
                                 (byte[])buffer.array()) 
                           + "\nPosition:"
                           + buffer.position() 
                           + "\nLimit:"
                           + buffer.limit()); 
  
        // Limit the Buffer 
        // using limit() method 
        buffer.limit(4); 
  
        // print the buffer 
        System.out.println("\nBuffer after operation:"
                           + Arrays.toString( 
                                 (byte[])buffer.array()) 
                           + "\nPosition:"
                           + buffer.position() 
                           + "\nLimit:"
                           + buffer.limit()); 
    } 
}

输出：

Buffer before operation:[20, 30, 40, 0, 0]
Position:3
Limit:5

Buffer after operation:[20, 30, 40, 0, 0]
Position:3
Limit:4

参考：https://docs.oracle.com/javase/9/docs/api/java/nio/Buffer.html#limit-int-

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注：本文由纯净天空筛选整理自RohitPrasad3大神的英文原创作品 Buffer limit() methods in Java with Examples。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。