Increment/Decrement inputted value in JTextField

Question

For my assignment, I need to make an application where I can increment or decrement the value in the JTextField and the color will change on the lower panel. The text field is editable so whenever any of the values in the top panel's text box changes, the lower panel's background color will immediately update to match it. However, I am having trouble with that.

I'm also having trouble limiting the entered input to values outside of 0 and 256 to be treated as zero.

Is there any pointers?

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

public class App1 extends JFrame implements ActionListener {
int value1 = 0, value2 = 0, value3 = 0; 
String svalue1, svalue2, svalue3; 
JPanel jp, p1, p2, p3, p4;
JLabel jl1, jl2, jl3; 
JTextField tf1, tf2, tf3; 
JButton b1, b2, b3, b4, b5, b6; 

public static void main(String[] args) {
    App1 app1 = new App1(); 

}

App1()
{
    this.setSize(800,600); 
    this.setTitle("Application 1");
    this.setDefaultCloseOperation(EXIT_ON_CLOSE);

    jp = new JPanel(); 
    jp.setBackground(new Color(value1,value2,value3));
    jp.setLayout(new GridLayout(2,1));
    this.add(jp);

    p1 = new JPanel();
    p1.setLayout(new GridLayout(1,3));
    jp.add(p1); 

    //Panel for "R"
    p2 = new JPanel();
    p2.setBackground(Color.RED);
    //p2.setLayout(new BoxLayout(p2, BoxLayout.Y_AXIS));;
    p1.add(p2);
    jl1 = new JLabel("Red"); p2.add(jl1); 
    b1 = new JButton("+");
    b1.addActionListener(this);
    p2.add(b1);
    tf1 = new JTextField("0"); tf1.setEditable(true); p2.add(tf1); 
    tf1.setBounds(140, 70, 200,30);
    b2 = new JButton("-");
    jl1.setAlignmentX(Component.CENTER_ALIGNMENT); tf1.setAlignmentX(Component.CENTER_ALIGNMENT);
    b1.setAlignmentX(Component.CENTER_ALIGNMENT); b2.setAlignmentX(Component.CENTER_ALIGNMENT);
    b2.addActionListener(this);
    p2.add(b2);

public void actionPerformed(ActionEvent e) {
    svalue1 = tf1.getText();
    value1 = Integer.parseInt(svalue1); 
    tf1.setText(svalue1);
    jp.setBackground(new Color(value1, value2, value3));

if(e.getSource() == b1) 
        {
            if(value1 < 256)
            value1++; tf1.setText("" + value1);
            //setBK(value1,value2,value3);
            jp.setBackground(new Color(value1,value2,value3));
        }
    if(e.getSource() == b2) 
        {
            if(value1 > 0)
            value1--; tf1.setText("" + value1);
            //setBK(value1,value2,value3);
            jp.setBackground(new Color(value1,value2,value3));
        }

writing your code as `if(value1 < 256) value1++; tf1.setText("" + value1);` is very very misleading. Is the `settext` also supposed to be part of the `if` statement (your formatting makes it appear that way). If so you are missing `{...}` — Scary Wombat, Nov 19 '18 at 00:20
You never updated the text of `tf1` after you incremented/decremented the old value. — Kevin Anderson, Nov 19 '18 at 00:48
1) For better help sooner, post a [MCVE] or [Short, Self Contained, Correct Example](http://www.sscce.org/). 2) Consider using a `JSpinner` with a [`SpinnerNumberModel`](https://docs.oracle.com/javase/8/docs/api/javax/swing/SpinnerNumberModel.html) instead. — Andrew Thompson, Nov 19 '18 at 01:50
*"the color will change"* Actually, can the spinner. Use a [`JColorChooser`](https://docs.oracle.com/javase/9/docs/api/javax/swing/JColorChooser.html). The user will thank you for it. — Andrew Thompson, Nov 19 '18 at 02:32
*"values outside of 0 and 256"* That should be *"0 and **255**"*.. — Andrew Thompson, Nov 19 '18 at 02:46
@Lavin - your actionPerformed method was not implemented properly. I have provided with a proper implementation. Please take a look and let me know if it solves your problem. Thanks. — Abu Faisal, Nov 22 '18 at 23:13

Abu Faisal · Answer 1 · 2018-11-19T02:09:36.323

Your actionPerformed method is not implemented properly. Please try this following code instead.

public void actionPerformed(ActionEvent e) {
    svalue1 = tf1.getText();
    value1 = Integer.parseInt(svalue1);

    if(e.getSource() == b1) {
        value1++;

        if(value1 >= 256) {
            value1 = 0;
        }
    }


     else if(e.getSource() == b2) {
        value1--;

        if (value1 < 0) {
            value1 = 0;
        }
     }

     tf1.setText("" + value1);
     jp.setBackground(new Color(value1, value2, value3));
}

Hope this helps!!

Increment/Decrement inputted value in JTextField

1 Answers1