Changing background color of JTextArea throws exceptions

Question

I have a swing application, and I've written code to change the background color of the JTextArea. However, it gives me exceptions.

Here is the code:

//1.JtextArea will work after maximize.
//2.on typing text,background  will slowly transform to black line by line.

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

public class TextArea {

    JTextArea area;
    JFrame frame;

    public static void main(String args[])                     
    {
        TextArea x = new TextArea();
        x.execute();                                                       
    }               

    void execute()
    {
        frame = new JFrame();
        frame.setVisible(true);
        frame.setSize(600,600);
        frame.setTitle("Temp Area");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        area = new JTextArea();
        frame.add(area,BorderLayout.CENTER);

        Color c = new Color(0,0,0,100);
        area.setBackground(c);
    }
}

Answer 1

• you need to move code line frame.setVisible(true); as last code in void execute()

• because you added JTextArea to the already visible Swing GUI, that isn't builded on Initial Thread

• another important:

  • rename public class TextArea { to public class MyTextArea {, because TextArea is reserved Java word for awt.TextArea

  • TextArea x=new TextArea(); and x.execute(); should be wrapped into invokeLater, more to se in Oracle tutorial Initial Thread