Java java.nio.Buffer用法及代碼示例

// Java program to demonstrate Buffer Class
// Importing required libraries
import java.nio.*;
import java.util.*;
// Main class
public class GFG {
    // Main driver method
    public static void main(String[] args)
    {
        // Declaring the capacity of the ByteBuffer
        int capacity = 5;
        // Try block to check for exceptions
        try {
            // Creating the ByteBuffer
            // Creating object of ByteBuffer class and
            // allocating size capacity
            ByteBuffer bufferObj
                = ByteBuffer.allocate(capacity);
            // Putting the int to byte typecast
            // value in ByteBuffer using put() method
            // Custom input entries
            bufferObj.put((byte)10);
            bufferObj.put((byte)20);
            bufferObj.put((byte)30);
            bufferObj.put((byte)40);
            bufferObj.put((byte)50);
            // Typecasting ByteBuffer into Buffer
            Buffer bufferObj1 = (Buffer)bufferObj;
            // Getting array that backs this buffer
            // using array() method
            byte[] arr = (byte[])bufferObj1.array();
            // Display message only
            System.out.print(" The array is : [");
            // Print the array
            for (int i = 0; i < arr.length; i++)
                System.out.print(" " + arr[i]);
            System.out.print(" ]");
        }
        // Catch block to handle the exception
        catch (ReadOnlyBufferException e) {
            // Print message where exception occurred
            // is displayed on console
            System.out.println("Exception throws: " + e);
        }
    }
}

// Java program to demonstrate Buffer class
// Importing required libraries
import java.nio.*;
import java.util.*;
// Main class
public class GFG {
    // Main driver method
    public static void main(String[] args)
    {
        // try block to check for exceptions
        try {
            // Creating and initializing byte array
            // with custom elements
            byte[] barr = { 10, 20, 30, 40, 50 };
            // Creating object of ByteBuffer class
            // and allocating size capacity
            ByteBuffer bufferObj = ByteBuffer.wrap(barr);
            // Typecasting ByteBuffer into Buffer
            Buffer bufferObj1 = (Buffer)bufferObj;
            // now trying to set the position at index 2
            bufferObj1.position(2);
            // Setting this buffer mark position
            // using mark() method
            bufferObj1.mark();
            // Again trying to set the position at index 4
            bufferObj1.position(5);
            // Display the position
            System.out.println("position before reset: "
                               + bufferObj1.position());
            // Now trying to call clear() to restore
            // to the position at index 0 by discarding the
            // mark
            bufferObj1.clear();
            // Print and display the position
            System.out.println("position after reset: "
                               + bufferObj1.position());
        }
        // Catch block to handle the exception
        catch (InvalidMarkException e) {
            // Display message to be showcase when exception
            // occurred
            System.out.println(
                "new position is less than "
                + "the position we marked before ");
            // Print the exception on the console
            // along with display message
            System.out.println("Exception throws: " + e);
        }
    }
}