Java Buffer limit()用法及代碼示例

java.nio.Buffer類的limit()方法用於設置此緩衝區的限製。如果位置大於新限製，則將其設置為新限製。如果標記已定義且大於新限製，則將其丟棄。

用法:

public Buffer limit(int newLimit)

返回值：此方法返回此緩衝區。

下麵是說明limit()方法的示例：

範例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()); 
    } 
}

輸出：

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

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

範例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()); 
    } 
}

輸出：

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

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

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

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注：本文由純淨天空篩選整理自RohitPrasad3大神的英文原創作品 Buffer limit() methods in Java with Examples。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。