How to use

repaint

method

in

java.awt.Component

return new Dimension(canvas.getWidth(), canvas.getHeight());
repaint();
repaint();
repaint();
repaint();
int width = 640;
int height = 480;
JFrame frame = new JFrame("Direct draw demo");
frame.add(panel);
frame.pack();
frame.setVisible(true);
frame.setResizable(false);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

this.setLayout(new BorderLayout());
checkBox = new JCheckBox();
add(checkBox, BorderLayout.CENTER);
setOpaque(false);
  selfPointer.repaint();                          

JScrollPane screenScroll = new JScrollPane(screenLabel);
screenScroll.setPreferredSize(new Dimension(
    (int)(screen.getWidth()/3),
    (int)(screen.getHeight()/3)));
panel.add(screenScroll, BorderLayout.CENTER);
panel.add(selectionLabel, BorderLayout.SOUTH);
screenLabel.repaint();
    repaint(screen, screenCopy);
    selectionLabel.setText("Start Point: " + start);
    screenLabel.repaint();
    Point end = me.getPoint();
    captureRect = new Rectangle(start,
        new Dimension(end.x-start.x, end.y-start.y));
    repaint(screen, screenCopy);
    screenLabel.repaint();
    selectionLabel.setText("Rectangle: " + captureRect);

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

public class Infout extends JFrame{
  Infout(){
    setSize(300, 400);
    setTitle("An Empty Frame");
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setVisible(true);
  }

  public static void main(String[] args) {
     Infout m = new Infout();
     m.repaint(); 
  }

  @Override
  public void paint(Graphics g) 
  {
     g.drawRect(5, 5, 105, 105);
  }

}

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

public class Main {
  public static void main(String[] args) {
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setVisible(true);
    frame.setSize(600, 400);

    JPanel panel = new JPanel() {
      @Override
      public void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.setColor(Color.BLUE);
        g.fillRect(0, 0, 100, 100);
      }
    };
    frame.add(panel);

    // Graphics g = panel.getGraphics();
    // g.setColor(Color.BLUE);
    // g.fillRect(0, 0, 100, 100);

    frame.validate(); // because you added panel after setVisible was called
    frame.repaint(); // because you added panel after setVisible was called
  }
}

public void mouseClicked(MouseEvent e) {
  isLiving = !isLiving;
  repaint();
for (int jj = 0; jj < s; jj++) {
  GameOfLife cell = new GameOfLife(ii, jj);
  cell.setPreferredSize(new Dimension(10, 10));
  gui.add(cell);
  biosphere[ii][jj] = cell;
  gui.repaint();

gui.add(quality, BorderLayout.WEST);
dithering = new JCheckBox("Dithering", false);
controls.add(antialiasing);
controls.add(fractionalMetrics);
gui.repaint();
updateText();

JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
frame.setSize(600, 400);
frame.add(panel);
frame.repaint(); // because you added panel after setVisible was called

 import java.awt.Dimension;
import java.awt.event.ActionEvent;
import javax.swing.AbstractAction;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JOptionPane;
import javax.swing.JPanel;

public class Main {
  public static void main(String[] args) {
   final JComboBox<String> myCombo = new JComboBox<String>(new String[]{"Foo", "Bar"});
   final JPanel mainPanel = new JPanel();
   mainPanel.setPreferredSize(new Dimension(250, 100));
   mainPanel.add(new JButton(new AbstractAction("Toggle Combo") {

     @Override
     public void actionPerformed(ActionEvent arg0) {
      myCombo.setVisible(!myCombo.isVisible());
      mainPanel.revalidate();
      mainPanel.repaint();
     }
   }));
   mainPanel.add(myCombo);

   JOptionPane.showMessageDialog(null, mainPanel);
  }

}

return new Dimension(PREF_W, PREF_H);
  currentPointList = new ArrayList<Point>();
  currentPointList.add(mEvt.getPoint());
  repaint();
public void mouseDragged(MouseEvent mEvt) {
  currentPointList.add(mEvt.getPoint());
  repaint();
  pointsList.add(currentPointList);
  currentPointList = null;
  repaint();
JFrame frame = new JFrame("DrawStuff");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new DrawStuff());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);

repaint();
repaint();
JFrame testFrame = new JFrame();
testFrame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
final LinesComponent comp = new LinesComponent();
comp.setPreferredSize(new Dimension(320, 200));
testFrame.getContentPane().add(comp, BorderLayout.CENTER);
JPanel buttonsPanel = new JPanel();
JButton newLineButton = new JButton("New Line");
JButton clearButton = new JButton("Clear");
buttonsPanel.add(newLineButton);
buttonsPanel.add(clearButton);
testFrame.getContentPane().add(buttonsPanel, BorderLayout.SOUTH);
newLineButton.addActionListener(new ActionListener() {
testFrame.pack();
testFrame.setVisible(true);

  JFrame frame = new JFrame("Testing");
  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  frame.setLayout(new BorderLayout());
  frame.add(new TestPane());
  frame.pack();
  frame.setLocationRelativeTo(null);
  frame.setVisible(true);
    repaint();
return new Dimension(200, 200);

      JFrame frame = new JFrame();
      frame.setLayout(new GridLayout(N, N, N, N));
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      for (int i = 0; i < N * N; i++) {
        frame.add(new RotatePanel());
      frame.pack();
      frame.setVisible(true);
  this.setPreferredSize(new Dimension(
    image.getWidth(null), image.getHeight(null)));
  this.addMouseListener(new MouseAdapter() {
public void actionPerformed(ActionEvent e) {
  theta += dt;
  repaint();
  return new Dimension(SIZE, SIZE);

this.scores = scores;
invalidate();
this.repaint();
mainPanel.setPreferredSize(new Dimension(800, 600));
JFrame frame = new JFrame("DrawGraph");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);

repaint();
  JFrame window = new JFrame();
  window.setSize(840, 560);
  window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  window.add(grid);
  window.setVisible(true);
  grid.fillCell(0, 0);
  grid.fillCell(79, 0);

JFrame f = new JFrame("AnimationTest");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(this);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
timer.start();
super(true);
this.setOpaque(false);
this.setPreferredSize(new Dimension(WIDE, HIGH));
this.addMouseListener(new MouseHandler());
this.addComponentListener(new ComponentHandler());
this.repaint();
  Dimension d = field.getPreferredSize();
  field.setBounds(e.getX(), e.getY(), d.width, d.height);
  add(field);

  for (int col = 0; col < GRID_COLS; col++) {
    panelGrid[row][col] = new JPanel(new GridBagLayout());
    backingPanel.add(panelGrid[row][col]);
redLabel.setBackground(Color.red.brighter().brighter());
redLabel.setPreferredSize(LABEL_SIZE);
panelGrid[4][3].add(redLabel);
panelGrid[1][1].add(blueLabel);
    clickedPanel.remove(dragLabel);
    clickedPanel.revalidate();
    clickedPanel.repaint();
    dragLabel.setLocation(x, y);
    add(dragLabel, JLayeredPane.DRAG_LAYER);
    repaint();
  int y = me.getPoint().y - dragLabelHeightDiv2;
  dragLabel.setLocation(x, y);
  repaint();
  repaint();
  dragLabel = null;

this.setPreferredSize(new Dimension(640, 480));
this.addMouseListener(mouseHandler);
this.addMouseMotionListener(mouseHandler);
  p1 = e.getPoint();
  p2 = p1;
  repaint();
  drawing = false;
  p2 = e.getPoint();
  repaint();
  if (drawing) {
    p2 = e.getPoint();
    repaint();
  this.add(new MoveButton("\u2190", KeyEvent.VK_LEFT, -DELTA, 0));
  this.add(new MoveButton("\u2191", KeyEvent.VK_UP, 0, -DELTA));
  this.add(new MoveButton("\u2192", KeyEvent.VK_RIGHT, DELTA, 0));
  this.add(new MoveButton("\u2193", KeyEvent.VK_DOWN, 0, DELTA));
        LinePanel.this.p1.translate(dx, dy);
        LinePanel.this.p2.translate(dx, dy);
        LinePanel.this.repaint();

JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(new MainPanel());
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
Control control = new Control(model, view);
JLabel label = new JLabel("Guess what color!", JLabel.CENTER);
this.add(label, BorderLayout.NORTH);
this.add(view, BorderLayout.CENTER);
this.add(control, BorderLayout.SOUTH);
  PieceButton pb = (PieceButton) e.getSource();
  icon.color = pb.piece.color;
  label.repaint();
  model.check(pb.piece);

    repaint();
   repaint();
JFrame test = new JFrame("Tab test");
test.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
test.setSize(400, 400);
tabs.addTab("Four", new JButton("Four"));
test.add(tabs);
test.setVisible(true);