LongBuffer compact() method in Java

The compact() method of java.nio.LongBuffer Class is used to compact the given buffer.

The values between the buffer’s current position and its limit are copied to the beginning of the buffer. The buffer’s position is then set to n+1 and its limit is set to its capacity. The buffer’s position is set to the number of floats copied.

Syntax:

public abstract LongBuffer compact()

Return Value: This method returns the new LongBuffer with the same content as that of this buffer.

Exception: This method throws the ReadOnlyBufferException, If this buffer is read-only.

Below program illustrates the compact() method:

Examples 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 LongBuffer 
        int capacity = 10; 
  
        // Creating the LongBuffer 
  
        // creating object of Longbuffer 
        // and allocating size capacity 
        LongBuffer ib = LongBuffer.allocate(capacity); 
  
        // putting the value in Longbuffer 
        ib.put(8); 
        ib.put(9); 
        ib.put(9); 
  
        // prLong the LongBuffer 
        System.out.println("Original LongBuffer: "
                           + Arrays.toString(ib.array())); 
  
        System.out.println("Position: " + ib.position()); 
  
        System.out.println("limit: " + ib.limit()); 
  
        // Creating a compacted  LongBuffer of same LongBuffer 
        // using compact() method 
        LongBuffer LongBuffer = ib.compact(); 
  
        // prLong the LongBuffer 
        System.out.println("\nCompacted LongBuffer: "
                           + Arrays.toString(LongBuffer.array())); 
  
        System.out.println("Position: " + LongBuffer.position()); 
  
        System.out.println("limit: " + LongBuffer.limit()); 
  
        // putting the value in compacted Longbuffer 
        LongBuffer.put(9); 
  
        // prLong the LongBuffer 
        System.out.println("\nUpdated Compacted LongBuffer: "
                           + Arrays.toString(LongBuffer.array())); 
        System.out.println("Position: " + LongBuffer.position()); 
        System.out.println("limit: " + LongBuffer.limit()); 
    } 
} 

Output:

Original LongBuffer: [8, 9, 9, 0, 0, 0, 0, 0, 0, 0]
Position: 3
limit: 10

Compacted LongBuffer: [0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
Position: 7
limit: 10

Updated Compacted LongBuffer: [0, 0, 0, 0, 0, 0, 0, 9, 0, 0]
Position: 8
limit: 10

Examples 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 LongBuffer 
        int capacity = 10; 
  
        // Creating the LongBuffer 
        try { 
  
            // creating object of LongBuffer 
            // and allocating size capacity 
            LongBuffer ib = LongBuffer.allocate(capacity); 
  
            // putting the value in Longbuffer 
            ib.put(8); 
            ib.put(9); 
            ib.put(9); 
            ib.rewind(); 
  
            // Creating a read-only copy of LongBuffer 
            // using asReadOnlyBuffer() method 
            LongBuffer ib1 = ib.asReadOnlyBuffer(); 
  
            // prLong the ReadOnlyBuffer 
            System.out.print("ReadOnlyBuffer LongBuffer: "); 
            while (ib1.hasRemaining()) 
                System.out.print(ib1.get() + ", "); 
            System.out.println(""); 
  
            // prLong the Position of LongBuffer ib 
            System.out.println("\nPosition: " + ib.position()); 
  
            // prLong the Limit of LongBuffer ib 
            System.out.println("\nlimit: " + ib.limit()); 
  
            // Creating a compacted  LongBuffer of same ReadOnlyBuffer 
            // using compact() method 
            System.out.println("\nTrying to compact the ReadOnlyBuffer ib1"); 
            LongBuffer LongBuffer = ib1.compact(); 
        } 
  
        catch (IllegalArgumentException e) { 
            System.out.println("Exception throws " + e); 
        } 
  
        catch (ReadOnlyBufferException e) { 
            System.out.println("Exception throws " + e); 
        } 
    } 
} 

Output:

ReadOnlyBuffer LongBuffer: 8, 9, 9, 0, 0, 0, 0, 0, 0, 0, 

Position: 0

limit: 10

Trying to compact the ReadOnlyBuffer ib1
Exception throws java.nio.ReadOnlyBufferException

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