Java IntBuffer compact()方法

java.nio.IntBuffer 类的 compact() 方法用于压缩给定的缓冲区。

缓冲区的当前位置和极限之间的值被复制到缓冲区的开头。然后，缓冲区的位置被设置为n+1，其极限被设置为其容量。缓冲区的位置被设置为复制的浮点数。

语法

public abstract IntBuffer compact()

返回值： 该方法返回新的IntBuffer，其内容与该缓冲区的内容相同。

异常： 如果这个缓冲区是只读的，这个方法会抛出 ReadOnlyBufferException 。

下面的程序说明了 compact() 方法。

例子 1 :

// Java program to demonstrate// compact() method  import java.nio.*;import java.util.*;  public class GFG {    public static void main(String[] args)    {          // Declaring the capacity of the IntBuffer        int capacity = 10;          // Creating the IntBuffer          // creating object of Intbuffer        // and allocating size capacity        IntBuffer ib = IntBuffer.allocate(capacity);          // putting the value in Intbuffer        ib.put(8);        ib.put(9);        ib.put(9);          // print the IntBuffer        System.out.println("Original IntBuffer: "                           + Arrays.toString(ib.array()));          System.out.println("Position: " + ib.position());          System.out.println("limit: " + ib.limit());          // Creating a compacted  IntBuffer of same IntBuffer        // using compact() method        IntBuffer IntBuffer = ib.compact();          // print the IntBuffer        System.out.println("\nCompacted IntBuffer: "                           + Arrays.toString(IntBuffer.array()));          System.out.println("Position: " + IntBuffer.position());          System.out.println("limit: " + IntBuffer.limit());          // putting the value in compacted Intbuffer        IntBuffer.put(9);          // print the IntBuffer        System.out.println("\nUpdated Compacted IntBuffer: "                           + Arrays.toString(IntBuffer.array()));        System.out.println("Position: " + IntBuffer.position());        System.out.println("limit: " + IntBuffer.limit());    }}

输出:

Original IntBuffer: [8, 9, 9, 0, 0, 0, 0, 0, 0, 0]Position: 3limit: 10Compacted IntBuffer: [0, 0, 0, 0, 0, 0, 0, 0, 0, 0]Position: 7limit: 10Updated Compacted IntBuffer: [0, 0, 0, 0, 0, 0, 0, 9, 0, 0]Position: 8limit: 10

实例2： 演示ReadOnlyBufferException

// Java program to demonstrate// compact() method  import java.nio.*;import java.util.*;  public class GFG {    public static void main(String[] args)    {          // Declaring the capacity of the IntBuffer        int capacity = 10;          // Creating the IntBuffer        try {              // creating object of IntBuffer            // and allocating size capacity            IntBuffer ib = IntBuffer.allocate(capacity);              // putting the value in Intbuffer            ib.put(8);            ib.put(9);            ib.put(9);            ib.rewind();              // Creating a read-only copy of IntBuffer            // using asReadOnlyBuffer() method            IntBuffer ib1 = ib.asReadOnlyBuffer();              // print the ReadOnlyBuffer            System.out.print("ReadOnlyBuffer IntBuffer: ");              while (ib1.hasRemaining())                System.out.print(ib1.get() + ", ");            System.out.println("");              // print the Position of IntBuffer ib            System.out.println("\nPosition: " + ib.position());              // print the Limit of IntBuffer ib            System.out.println("\nlimit: " + ib.limit());              // Creating a compacted  IntBuffer of same ReadOnlyBuffer            // using compact() method            System.out.println("\nTrying to compact the ReadOnlyBuffer ib1");              IntBuffer IntBuffer = ib1.compact();        }          catch (IllegalArgumentException e) {            System.out.println("Exception throws " + e);        }          catch (ReadOnlyBufferException e) {            System.out.println("Exception throws " + e);        }    }}

输出:

ReadOnlyBuffer IntBuffer: 8, 9, 9, 0, 0, 0, 0, 0, 0, 0, Position: 0limit: 10Trying to compact the ReadOnlyBuffer ib1Exception throws java.nio.ReadOnlyBufferException