In Part 2, I showed how to create a simple health value display with two buttons, one to ‘hurt’ the player and one to ‘heal’ the player.  This post will show how to display and update a health status bar each time the health value is changed.

In this post we will be making a newer version of this application which will include a graphical bar representing the health value.

After clicking on the ‘hurt’ button several times you can see that the healthStatus JLabel has updated, and the healthBar has redrawn.

To get started first we create instance variables…
[pyg language="java" style="manni"]
public class Main {

int healthval = 100;

Bar healthBar;
JLabel healthStatus = new JLabel(“HP: ” + healthval);
[/pyg]
Next our program call

[pyg language="java" style="manni"]
public static void main(String[] args){
Main gui = new Main();
gui.start();
}
[/pyg]

Here we have our start() method where you should note that the healthStatus JLabel get’s a preferred size assigned to it, so that when frame.pack() get’s called the size of the frame remains constant.

[pyg language="java" style="manni"]
public void start(){
JFrame frame = new JFrame();
JPanel buttonPanel = new JPanel();
JPanel barPanel = new JPanel();

JButton heal = new JButton(“Heal”);
JButton hurt = new JButton(“Hurt”);
healthStatus.setPreferredSize(new Dimension(45,10));

heal.addActionListener(new HealListener());
hurt.addActionListener(new HurtListener());

healthBar = new Bar(healthval);

buttonPanel.add(heal);
buttonPanel.add(hurt);
barPanel.add(healthStatus);
barPanel.add(healthBar);

frame.getContentPane().add(BorderLayout.NORTH, barPanel);
frame.getContentPane().add(BorderLayout.SOUTH, buttonPanel);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
frame.pack();
}
[/pyg]

Finally for the Main.java class we have our two action listeners (one for each button…

[pyg language="java" style="manni"]
class HealListener implements ActionListener{
public void actionPerformed(ActionEvent ev){
healthval++;
healthBar.setVal(healthval);
healthStatus.setText(“HP: ” + healthval);
}
}
[/pyg]

[pyg language="java" style="manni"]
class HurtListener implements ActionListener{
public void actionPerformed(ActionEvent ev){
healthval–;
healthBar.setVal(healthval);
healthStatus.setText(“HP: ” + healthval);
}
}
[/pyg]

Next we need to create a Bar.java class to create the healthBar, and to provide the Bar.setVal(int) method.

[pyg language="java" style="manni"]
package healthbar;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;

import javax.swing.JComponent;

public class Bar extends JComponent{

private int healthval;

public Bar(int hv){
setPreferredSize(new Dimension(100,10));
this.healthval = hv;
}

public void paintComponent(Graphics g){
super.paintComponent(g);
g.setColor(Color.PINK);
g.fillRect(0,0, 100, 10);
g.setColor(Color.red);
g.fillRect(0, 0, healthval, 10);
}

public void setVal(int val){
healthval = val;
repaint();
}
}
[/pyg]

Here is the full Main.java class…

[pyg language="java" style="manni"]
package healthbar;

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

public class Main {

int healthval = 100;

Bar healthBar;
JLabel healthStatus = new JLabel(“HP: ” + healthval);

public static void main(String[] args){
Main gui = new Main();
gui.start();
}

public void start(){
JFrame frame = new JFrame();
JPanel buttonPanel = new JPanel();
JPanel barPanel = new JPanel();

JButton heal = new JButton(“Heal”);
JButton hurt = new JButton(“Hurt”);
healthStatus.setPreferredSize(new Dimension(45,10));

heal.addActionListener(new HealListener());
hurt.addActionListener(new HurtListener());

healthBar = new Bar(healthval);

buttonPanel.add(heal);
buttonPanel.add(hurt);
barPanel.add(healthStatus);
barPanel.add(healthBar);

frame.getContentPane().add(BorderLayout.NORTH, barPanel);
frame.getContentPane().add(BorderLayout.SOUTH, buttonPanel);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
frame.pack();
}

class HealListener implements ActionListener{
public void actionPerformed(ActionEvent ev){
healthval++;
healthBar.setVal(healthval);
healthStatus.setText(“HP: ” + healthval);
}
}

class HurtListener implements ActionListener{
public void actionPerformed(ActionEvent ev){
healthval–;
healthBar.setVal(healthval);
healthStatus.setText(“HP: ” + healthval);
}
}

}
[/pyg]