BufferedImage image;

image = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);

Graphics g;

g = image.getGraphics();
//do some drawing here with g etc.
g.dispose();

int[] imgArray;

imgArray = ((DataBufferInt)image.getRaster().getDataBuffer()).getData()
//Now you can directly mess with the integer RGB values in imgArray[].

package solitaire;

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import javax.swing.event.*;
import java.util.*;

public class Solitaire implements MouseInputListener {
    
    ArrayList<Card> cards = new ArrayList<>();
    
    JFrame frame;
    SolitairePanel panel;
    
    int screenWidth = 800;
    int screenHeight = 600;
    
    //variables for card selection
    boolean cardSelected;
    Card selectedCard;
    Point lastPosition = new Point();
    
    Solitaire() {
       
        //Setting up the display
        frame = new JFrame();
        panel = new SolitairePanel(screenWidth, screenHeight, this);
        panel.addMouseListener(this);
        panel.addMouseMotionListener(this);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setResizable(false);
        frame.add(panel);
        frame.pack();
        frame.setVisible(true);
        
        //Adding some cards
        cards.add(new Card(50,50));
        cards.add(new Card(200, 200));
        
    }
    
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        Solitaire solitaire = new Solitaire();
        solitaire.go();
    }
    
    public void go(){
        
        //Bad loop just for demonstration.
        while(true){
            frame.repaint();
            try {
                Thread.sleep(16);
            } catch (Exception ex) {
                
            }
        }
    }

    @Override
    public void mousePressed(MouseEvent me) {
        
        for(int x = 0; x < cards.size(); x++) {
            if(cards.get(x).bounds.contains(me.getPoint())) {
                this.cardSelected = true;
                selectedCard = cards.get(x);
                lastPosition.setLocation(me.getPoint());
                break;
            }
        }    
    }

    @Override
    public void mouseDragged(MouseEvent me) {

        if(cardSelected){
            selectedCard.move((int)(me.getX() - lastPosition.getX()), (int)(me.getY() - lastPosition.getY()));
        }
        
        lastPosition.setLocation(me.getPoint());
    }
    
     @Override
    public void mouseReleased(MouseEvent me) {
        
         //NOTE: you would probably check if the card move is valid here. If so, update game, stacks, bounds etc. If not, return card to original position.
         if(cardSelected) {
            selectedCard.updateBounds();
            cardSelected = false;
         }       
    }   
    
     
     //Following methods aren't used.
     
    @Override
    public void mouseClicked(MouseEvent me) {}
    
    @Override
    public void mouseMoved(MouseEvent me) {}
    
    @Override
    public void mouseEntered(MouseEvent me) {}

    @Override
    public void mouseExited(MouseEvent me) {}
}

package solitaire;

import java.awt.*;
import javax.swing.*;

public class SolitairePanel extends JPanel {
    
    Solitaire game;
    int width;
    int height;
    
    SolitairePanel(int width, int height, Solitaire game) {
        this.game = game;  
        this.width = width;
        this.height = height;
        this.setPreferredSize(new Dimension(width, height));
    }
    
    @Override
    public void paint(Graphics g) {

        g.setColor(Color.black);
        g.fillRect(0, 0, width, height);
        
        for(int x = 0; x < game.cards.size(); x++) {
            game.cards.get(x).render(g);
        }
        
    }
}

package solitaire;

import java.awt.*;

public class Card {
    
    int width = 120;
    int height = 150;
    
    int xPos;
    int yPos;
    
    Rectangle bounds;
    
    Card(int xPos, int yPos) {
        this.xPos = xPos;
        this.yPos = yPos;
        bounds = new Rectangle(xPos, yPos, width, height);
    }
    
    //Move the card by setting the offset from its current position.
    public void move(int xOffset, int yOffset) {
        
        xPos += xOffset;
        yPos += yOffset;
        
    }
    
    //Update the bounds of the card, so that it can be selected.
    public void updateBounds() {
        bounds.setBounds(xPos, yPos, width, height);
    }
    
    public void render(Graphics g) {
        g.setColor(Color.red);
        g.fillRect(xPos, yPos, width, height);
        g.setColor(Color.blue);
        g.drawRect(xPos, yPos, width, height);
    } 
}