Java中的 FloatBuffer limit() 方法及示例

Java.nio.FloatBuffer 类的limit()方法用来修改这个FloatBuffer 的限制。此方法将要设置的限制作为参数，并将其设置为此 Buffer 的新限制。如果这个 Buffer 的标记已经定义并且大于新的指定限制，那么这个新的限制不会被设置并被丢弃。

句法：

public final FloatBuffer limit(int newLimit)

参数：该方法接受一个整数类型的参数newLimit ，它指的是要设置为缓冲区的新限制的限制。

返回值：该方法将指定的新限制设置为该Buffer的新限制后返回该缓冲区。

下面的示例说明了 limit() 方法：

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 FloatBuffer
        // using allocate() method
        FloatBuffer floatBuffer
            = FloatBuffer.allocate(4);
  
        // put float value in FloatBuffer
        // using put() method
        floatBuffer.put(20.5f);
        floatBuffer.put(30.5f);
  
        // print the float buffer
        System.out.println(
            "FloatBuffer before "
            + "setting buffer's limit: "
            + Arrays.toString(
                  floatBuffer.array())
            + "\nPosition: "
            + floatBuffer.position()
            + "\nLimit: "
            + floatBuffer.limit());
  
        // Limit the floatBuffer
        // using limit() method
        floatBuffer.limit(1);
  
        // print the float buffer
        System.out.println(
            "\nFloatBuffer after "
            + "setting buffer's limit: "
            + Arrays.toString(
                  floatBuffer.array())
            + "\nPosition: "
            + floatBuffer.position()
            + "\nLimit: "
            + floatBuffer.limit());
    }
}

输出：

FloatBuffer before setting buffer’s limit:
[20.5, 30.5, 0.0, 0.0]
Position: 2
Limit: 4

FloatBuffer after setting buffer’s limit:
[20.5, 30.5, 0.0, 0.0]
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 FloatBuffer
        // using allocate() method
        FloatBuffer floatBuffer
            = FloatBuffer.allocate(5);
  
        // put float value in FloatBuffer
        // using put() method
        floatBuffer.put(20.5f);
        floatBuffer.put(30.5f);
        floatBuffer.put(40.5f);
  
        // mark will be going to
        // discarded by limit()
        floatBuffer.mark();
  
        // print the float buffer
        System.out.println(
            "FloatBuffer before "
            + "setting buffer's limit: "
            + Arrays.toString(
                  floatBuffer.array())
            + "\nPosition: "
            + floatBuffer.position()
            + "\nLimit: "
            + floatBuffer.limit());
  
        // Limit the floatBuffer
        // using limit() method
        floatBuffer.limit(4);
  
        // print the double buffer
        System.out.println(
            "\nFloatBuffer before "
            + "setting buffer's limit: "
            + Arrays.toString(
                  floatBuffer.array())
            + "\nPosition: "
            + floatBuffer.position()
            + "\nLimit: "
            + floatBuffer.limit());
    }
}

输出：

FloatBuffer before setting buffer’s limit:
[20.5, 30.5, 40.5, 0.0, 0.0]
Position: 3
Limit: 5

FloatBuffer before setting buffer’s limit:
[20.5, 30.5, 40.5, 0.0, 0.0]
Position: 3
Limit: 4

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