Need to add a "public static void main(String[] args)",

Question

I'm trying to make a code in Eclipse that change the color and text on MyButton when clicked.

Edit: Got some help and the problem Error got solved. I now know that the code need "public static void main(String[] args)" where should that be put?

After I try to run this code I get the Error "The selection can't be launched, and there are no recent launches". However, I've googled it and saw that the error may be a common problem in eclipse. I am, although new to java and presume it would be more logical if there's wrong with my code rather than eclipse hate me.

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

    public class Makke extends JFrame implements ActionListener{


        private JButton MyButton;

        public Makke(){
            setLayout(null);
            setSize(300, 250);
            setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            MyButton = new JButton("Tryck För Blå!");
            MyButton.setBackground(Color.YELLOW);
            MyButton.setBounds(100, 190, 60, 30);
            MyButton.addActionListener(this);
            add (MyButton);
        }

        public void actionPerformed(ActionEvent e) {
            if (e.getSource() == MyButton) {
                MyButton = new JButton("Tryck För Gul!");
                MyButton.setBackground(Color.BLUE);

            }

        }
        }

Translation: There is some Swedish in the code "Tryck för blå" = "Click to get blue", "Tryck för gul" = "Click to get yellow" ^^

I didn't know people were still using Swing... If you have a choice, you should really check out JavaFX. — Joffrey, Feb 07 '16 at 11:25
@Satya I get the error "The selection can't be launched, and there are no recent launches" — robbin modigh, Feb 07 '16 at 11:25
@Joffrey Ah, well there's a homework so I've got to use swing. But I'll keep that in mind in future coding :) — robbin modigh, Feb 07 '16 at 11:26
http://stackoverflow.com/questions/9240333/selection-cannot-be-launched-and-there-are-no-recent-launches-when-eclipse-for — SatyaTNV, Feb 07 '16 at 11:32
@Satya Actually that helped me out thank you. Eclipse told me that I need to insert "public static void main(String[] args)". Got any clue where this would be needed? — robbin modigh, Feb 07 '16 at 11:41
@robbinmodigh Then please tell your teacher to update his course ;-) — Joffrey, Feb 07 '16 at 12:07

score 0 · Answer 1 · edited Feb 07 '16 at 12:06

0

You are creating a new button everytime you click on it, but no clicklistener is added to that new object... My recomendation is to do this (or maybe better if you move to javaFX)

JButton myButton = new JButton("Text Button");
myButton.addActionListener(new ActionListener()
{
  public void actionPerformed(ActionEvent e)
  {
      myButton.setText("Tryck För Gul!");
      myButton.setBackground(Color.BLUE);
  }
}

edited Feb 07 '16 at 12:06

Joffrey

32,348
6
68
100

answered Feb 07 '16 at 11:35

ΦXocę 웃 Пepeúpa ツ

47,427
17
69
97

Ah I see, you're right. Did not think of that. Need to use Swing.* for my homework though but I will fix that :) Thanks – robbin modigh Feb 07 '16 at 11:46

score 0 · Accepted Answer · edited May 23 '17 at 12:07

1.You should set setVisible( boolean b) to true.

It Shows or hides this Window depending on the value of parameter b.

setVisible(true);

Add this line should be in the constructor of Makke class.

Read setVisible(boolean) doc

2.Your actionPerformed(.) method

if (e.getSource() == MyButton) {
   //MyButton = new JButton("Tryck För Gul!"); remove this line
  //otherwise every time new button object will be created.
    MyButton.setText("Tryck För Gul!");//to change the button text
    MyButton.setBackground(Color.BLUE);
}

3.Need main method to run your app. Create a class contains main(-) to run your app, in that create object of Makke class.

public class Main {
public static void main(String []args)throws Exception {

        new Makke();//now your window will be appeared.
}
}

Read - Why main(-) method needed

Thank you! That helped me a lot! You're awesome :) – robbin modigh Feb 07 '16 at 16:46 — robbin modigh, Feb 07 '16 at 16:46
Yes! My bad, I'm new to this place – robbin modigh Feb 07 '16 at 17:07 — robbin modigh, Feb 07 '16 at 17:07

Need to add a "public static void main(String[] args)",

2 Answers2