Java中的 CharBuffer limit() 方法及示例

Java.nio.CharBuffer 类的limit()方法用于设置这个缓冲区的限制。如果头寸大于新限制，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。

句法：

public CharBuffer limit(int newLimit)

返回值：此方法返回此缓冲区。

以下是说明 limit() 方法的示例：

示例 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 CharBuffer
        // using allocate() method
        CharBuffer charBuffer = CharBuffer.allocate(4);
  
        // append char value in CharBuffer
        // using char() method
        charBuffer.append('a');
        charBuffer.append('b');
  
        // print the char buffer
        System.out.println("CharBuffer before "
                           + "setting buffer's limit: "
                           + Arrays.toString(
                                 charBuffer.array())
                           + "\nPosition: "
                           + charBuffer.position()
                           + "\nLimit: "
                           + charBuffer.limit());
  
        // Limit the CharBuffer
        // using limit() method
        charBuffer.limit(1);
  
        // print the char buffer
        System.out.println("CharBuffer before "
                           + "setting buffer's limit: "
                           + Arrays.toString(
                                 charBuffer.array())
                           + "\nPosition: "
                           + charBuffer.position()
                           + "\nLimit: "
                           + charBuffer.limit());
    }
}

输出：

CharBuffer before setting buffer's limit: [a, b,,  ]
Position: 2
Limit: 4

CharBuffer after setting buffer's limit: [a, b,,  ]
Position: 1
Limit: 1

示例 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 CharBuffer
        // using allocate() method
        CharBuffer charBuffer
            = CharBuffer.allocate(5);
  
        // append char value in CharBuffer
        // using char() method
        charBuffer.append('a');
        charBuffer.append('b');
        charBuffer.append('c');
  
        // mark will be going to discarded by limit()
        charBuffer.mark();
  
        // print the char buffer
        System.out.println("CharBuffer before "
                           + "setting buffer's limit: "
                           + Arrays.toString(
                                 charBuffer.array())
                           + "\nPosition: "
                           + charBuffer.position()
                           + "\nLimit: "
                           + charBuffer.limit());
  
        // Limit the charBuffer
        // using limit() method
        charBuffer.limit(4);
  
        // print the char buffer
        System.out.println("CharBuffer before "
                           + "setting buffer's limit: "
                           + Arrays.toString(
                                 charBuffer.array())
                           + "\nPosition: "
                           + charBuffer.position()
                           + "\nLimit: "
                           + charBuffer.limit());
    }
}

输出：

CharBuffer before setting buffer's limit: [a, b, c,,  ]
Position: 3
Limit: 5

CharBuffer after setting buffer's limit: [a, b, c,,  ]
Position: 3
Limit: 4

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