Java FloatBuffer compact()方法及实例

java.nio.FloatBuffer 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 FloatBuffer compact()

返回值： 本方法返回新的FloatBuffer，其内容与本缓冲区的内容相同。

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 FloatBuffer        int capacity = 10;          // Creating the FloatBuffer          // creating object of floatbuffer        // and allocating size capacity        FloatBuffer fb = FloatBuffer.allocate(capacity);          // putting the value in floatbuffer        fb.put(8.56F);        fb.put(9.61F);        fb.put(9.61F);          // print the FloatBuffer        System.out.println("Original FloatBuffer: "                           + Arrays.toString(fb.array()));          System.out.println("Position: " + fb.position());          System.out.println("limit: " + fb.limit());          // Creating a compacted  FloatBuffer of same FloatBuffer        // using compact() method        FloatBuffer floatBuffer = fb.compact();          // print the FloatBuffer        System.out.println("\nCompacted FloatBuffer: "                           + Arrays.toString(floatBuffer.array()));          System.out.println("Position: " + floatBuffer.position());          System.out.println("limit: " + floatBuffer.limit());          // putting the value in compacted floatbuffer        floatBuffer.put(9.61F);          // print the FloatBuffer        System.out.println("\nUpdated Compacted FloatBuffer: "                           + Arrays.toString(floatBuffer.array()));        System.out.println("Position: " + floatBuffer.position());        System.out.println("limit: " + floatBuffer.limit());    }}

输出。

Original FloatBuffer: [8.56, 9.61, 9.61, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]Position: 3limit: 10Compacted FloatBuffer: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]Position: 7limit: 10Updated Compacted FloatBuffer: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 9.61, 0.0, 0.0]Position: 8limit: 10

例子 2 :

// 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 FloatBuffer        int capacity = 10;          // Creating the FloatBuffer        try {              // creating object of FloatBuffer            // and allocating size capacity            FloatBuffer fb = FloatBuffer.allocate(capacity);              // putting the value in floatbuffer            fb.put(8.56F);            fb.put(9.61F);            fb.put(9.61F);            fb.rewind();              // Creating a read-only copy of FloatBuffer            // using asReadOnlyBuffer() method            FloatBuffer fb1 = fb.asReadOnlyBuffer();              // print the ReadOnlyBuffer            System.out.print("ReadOnlyBuffer FloatBuffer: ");            while (fb1.hasRemaining())                System.out.print(fb1.get() + ", ");            System.out.println("");              // print the Position of FloatBuffer fb            System.out.println("\nPosition: " + fb.position());              // print the Limit of FloatBuffer fb            System.out.println("\nlimit: " + fb.limit());              // Creating a compacted  FloatBuffer of same ReadOnlyBuffer            // using compact() method            System.out.println("\nTrying to compact the ReadOnlyBuffer fb1");            FloatBuffer floatBuffer = fb1.compact();        }          catch (IllegalArgumentException e) {              System.out.println("Exception throws " + e);        }          catch (ReadOnlyBufferException e) {              System.out.println("Exception throws " + e);        }    }}

输出。

ReadOnlyBuffer FloatBuffer: 8.56, 9.61, 9.61, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, Position: 0limit: 10Trying to compact the ReadOnlyBuffer fb1Exception throws java.nio.ReadOnlyBufferException