Question

package timing;
import java.awt.event.*;
import javax.swing.*;

public class Timing implements ActionListener{
    JButton button1;
    JLabel label1;
    public int minutes=3;//initial time
    public int time=minutes*60;//total amount of time in seconds only
    public int seconds=time%60;
    public String defaulttimeset="0"+Integer.toString(minutes)+":0"+Integer.toString(seconds);

    public static void main(String[] args) {
        Timing move=new Timing();
        move.go();
    }
    public void go(){
        JFrame frame=new JFrame();
        frame.setBounds(50,50,400,400);
        JPanel panel2=new JPanel();
        button1=new JButton("Start Time");
        panel2.add(button1);
       
        button1.setBounds(30,50,150,170);
        frame.getContentPane().add(button1);
       
        button1.addActionListener(this);
       
        label1=new JLabel(defaulttimeset);
        panel2.add(label1);       
        frame.getContentPane().add(panel2);
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    }
    public void actionPerformed(ActionEvent ev){
        for (int i=0;i<time;i++){
            String mi,s;
            if(seconds==0)
            {
                minutes--;
                seconds=60;
            }
            seconds--;
            mi="0"+Integer.toString(minutes);
            if (seconds<10){
                s="0"+Integer.toString(seconds);
            }
            else{
                s=Integer.toString(seconds);
            }
            defaulttimeset=mi+":"+s;
            label1.setText(defaulttimeset);

            try{
                Thread.sleep(1000);
            }
            catch(Exception ex){System.out.println("how is this a countdown?");
            }
        }
    }
}

the code was supposed to change the text of label1 upon clicking the button but it didn't change. is there something wrong with the code?

Answer 1

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

public class Timing implements ActionListener{
JButton button1;
JLabel label1;
public int minutes=3;//initial time
public int time=minutes*60;//total amount of time in seconds only
public int seconds=time%60;
public String defaulttimeset="0"+Integer.toString(minutes)+":0"+Integer.toString(seconds);

public static void main(String[] args) {
Timing move=new Timing();
move.go();
}
public void go(){
JFrame frame=new JFrame();
frame.setBounds(50,50,400,400);
JPanel panel2=new JPanel();
button1=new JButton("Start Time");
panel2.add(button1);

button1.setBounds(30,50,150,170);
frame.getContentPane().add(button1);

button1.addActionListener(this);

label1=new JLabel(defaulttimeset);
panel2.add(label1);   
frame.getContentPane().add(panel2);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

}
public void actionPerformed(ActionEvent ev){
   minutes=0;
   minutes=3;//initial time
time=minutes*60;//total amount of time in seconds only
seconds=time%60;
   new T(this).start();
}
}
class T extends Thread{
   Timing t;
   public T(Timing aTiming) {
       t=aTiming;
      
   }

   public void run(){
       for (int i=0;i<t.time;i++){
String mi,s;
if(t.seconds==0)
{
   t.minutes--;
   t.seconds=60;
}
t.seconds--;
mi="0"+Integer.toString(t.minutes);
if (t.seconds<10){
s="0"+Integer.toString(t.seconds);
}
else{
s=Integer.toString(t.seconds);
}
t.defaulttimeset=mi+":"+s;
t.label1.setText(t.defaulttimeset);

try{
Thread.sleep(1);
}
catch(Exception ex){System.out.println("how is this a countdown?");
}
}
}
}

Note: you need to use multi threading to update the time