Java DoubleBuffer limit()方法及实例

java.nio.DoubleBuffer类的 limit() 方法是用来修改这个DoubleBuffer的极限。这个方法以要设置的极限为参数，并将其设置为这个Buffer的新极限。如果这个Buffer的标记已经被定义，并且大于新指定的极限，那么这个新的极限就不会被设置并被丢弃。

语法

public final DoubleBuffer limit(int newLimit)

返回值： 该方法在将指定的新极限作为该Buffer的新极限后返回该Buffer。

下面是说明limit()方法的例子。

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

输出:

DoubleBuffer before setting buffer's limit: [20.5, 30.5, 0.0, 0.0]Position: 2Limit: 4DoubleBuffer after setting buffer's limit: [20.5, 30.5, 0.0, 0.0]Position: 1Limit: 1

例子 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 DoubleBuffer        // using allocate() method        DoubleBuffer doubleBuffer            = DoubleBuffer.allocate(5);          // put double value in DoubleBuffer        // using put() method        doubleBuffer.put(20.5);        doubleBuffer.put(30.5);        doubleBuffer.put(40.5);          // mark will be going to        // discarded by limit()        doubleBuffer.mark();          // print the double buffer        System.out.println("DoubleBuffer before "                           + "setting buffer's limit: "                           + Arrays.toString(                                 doubleBuffer.array())                           + "\nPosition: "                           + doubleBuffer.position()                           + "\nLimit: "                           + doubleBuffer.limit());          // Limit the doubleBuffer        // using limit() method        doubleBuffer.limit(4);          // print the double buffer        System.out.println("\nDoubleBuffer before "                           + "setting buffer's limit: "                           + Arrays.toString(                                 doubleBuffer.array())                           + "\nPosition: "                           + doubleBuffer.position()                           + "\nLimit: "                           + doubleBuffer.limit());    }}

输出:

DoubleBuffer before setting buffer's limit: [20.5, 30.5, 40.5, 0.0, 0.0]Position: 3Limit: 5DoubleBuffer before setting buffer's limit: [20.5, 30.5, 40.5, 0.0, 0.0]Position: 3Limit: 4

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