Java DoubleBuffer compact()用法及代碼示例

java.nio.DoubleBuffer類的compact()方法用於壓縮給定的緩衝區。

緩衝區當前位置與其極限之間的值將複製到緩衝區的開頭。然後將緩衝區的位置設置為n + 1，並將其限製設置為其容量。緩衝區的位置設置為複製的浮點數。

用法:

public abstract DoubleBuffer compact()

返回值：此方法返回具有與此緩衝區相同內容的新DoubleBuffer。

異常：如果此緩衝區是隻讀的，則此方法引發ReadOnlyBufferException。

以下示例程序旨在說明compact()方法：

範例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()); 
    } 
}

輸出：

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

範例2：顯示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); 
        } 
    } 
}

輸出：

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

相關用法

注：本文由純淨天空篩選整理自pawan_asipu大神的英文原創作品 DoubleBuffer compact() method in Java With Examples。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。