Java DoubleBuffer compact()用法及代码示例

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

缓冲区当前位置与其极限之间的值将复制到缓冲区的开头。然后将缓冲区的位置设置为n + 1，并将其限制设置为其容量。缓冲区的位置设置为复制的浮点数。

用法:

public abstract DoubleBuffer compact()

返回值：此方法返回具有与此缓冲区相同内容的新DoubleBuffer。

异常：如果此缓冲区是只读的，则此方法引发ReadOnlyBufferException。

以下示例程序旨在说明compact()方法：

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

输出：

Original DoubleBuffer: [8.5600004196167, 9.609999656677246, 9.609999656677246, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
Position: 3
limit: 10

Compacted DoubleBuffer: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
Position: 7
limit: 10

Updated Compacted DoubleBuffer: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 9.609999656677246, 0.0, 0.0]
Position: 8
limit: 10

范例2：显示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 DoubleBuffer 
        int capacity = 10; 
  
        // Creating the DoubleBuffer 
        try { 
  
            // creating object of DoubleBuffer 
            // and allocating size capacity 
            DoubleBuffer db = DoubleBuffer.allocate(capacity); 
  
            // putting the value in Doublebuffer 
            db.put(8.56F); 
            db.put(9.61F); 
            db.put(9.61F); 
            db.rewind(); 
  
            // Creating a read-only copy of DoubleBuffer 
            // using asReadOnlyBuffer() method 
            DoubleBuffer db1 = db.asReadOnlyBuffer(); 
  
            // print the ReadOnlyBuffer 
            System.out.print("ReadOnlyBuffer DoubleBuffer: "); 
            while (db1.hasRemaining()) 
                System.out.print(db1.get() + ", "); 
            System.out.println(""); 
  
            // print the Position of DoubleBuffer db 
            System.out.println("\nPosition: " + db.position()); 
  
            // print the Limit of DoubleBuffer db 
            System.out.println("\nlimit: " + db.limit()); 
  
            // Creating a compacted  DoubleBuffer of same ReadOnlyBuffer 
            // using compact() method 
            System.out.println("\nTrying to compact the ReadOnlyBuffer db1"); 
            DoubleBuffer DoubleBuffer = db1.compact(); 
        } 
  
        catch (IllegalArgumentException e) { 
  
            System.out.println("Exception throws " + e); 
        } 
  
        catch (ReadOnlyBufferException e) { 
  
            System.out.println("Exception throws " + e); 
        } 
    } 
}

输出：

ReadOnlyBuffer DoubleBuffer: 8.5600004196167, 9.609999656677246, 9.609999656677246, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 

Position: 0

limit: 10

Trying to compact the ReadOnlyBuffer db1
Exception throws java.nio.ReadOnlyBufferException

相关用法

注：本文由纯净天空筛选整理自pawan_asipu大神的英文原创作品 DoubleBuffer compact() method in Java With Examples。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。