Thread: Stuck in converting meters in milimeters

here's my code:

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
 
public class Milimetri extends JFrame {
 
private JPanel p1 = new JPanel(new FlowLayout(FlowLayout.LEFT));
private JPanel p2 = new JPanel(new FlowLayout(FlowLayout.LEFT));
private JPanel p3 = new JPanel(new FlowLayout(FlowLayout.LEFT));
 
private JLabel e1 = new JLabel("Meters");
private JLabel e2 = new JLabel("Milimeters:");
 
private JTextField t1 = new JTextField(20);
private JTextField t2 = new JTextField(20);
 
private JButton b1 = new JButton("Result");
 
public Milimetri(){
super("Metri in Centimetri");
setLayout(new GridLayout(3,1));
add(p1); add(p2); add(p3);
 
p1.add(e1);p1.add(t1);
p2.add(e2);p2.add(t2);
p3.add(b1);
 
pack();
setResizable(false);
setLocationRelativeTo(null);
setVisible(true);
 
b1.addActionListener(
new ActionListener(){
public void actionPerformed(ActionEvent ev){
double meters = Double.parseDouble(t1.getText());
String milimeters = t2.setText();
 
}
 
}
);
 
}

When i write a value in meters ..and press the button b1 to show me a value in milimeters...but i don't know what to do!

Pls help!

have a nice day!

PS: i hope i posted correctly

You had it nearly there, you needed to convert the meters to millimetres by multiplying by 1000, save the result in a double variable.

Then set the text box value using setText() to the double value in the millimetres variable but you need to convert it back to a string first by using Double.toString().


Please see my quick mock up below (this works):

package milimetri;
 
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
 
public class Milimetri extends JFrame
{
 
    private JPanel p1 = new JPanel(new FlowLayout(FlowLayout.LEFT));
    private JPanel p2 = new JPanel(new FlowLayout(FlowLayout.LEFT));
    private JPanel p3 = new JPanel(new FlowLayout(FlowLayout.LEFT));
 
    private JLabel e1 = new JLabel("Meters");
    private JLabel e2 = new JLabel("Milimeters:");
 
    private JTextField t1 = new JTextField(20);
    private JTextField t2 = new JTextField(20);
 
    private JButton b1 = new JButton("Result");
 
    public Milimetri()
    {
        super("Metri in Centimetri");
        setLayout(new GridLayout(3,1));
        add(p1);
        add(p2);
        add(p3);
 
        p1.add(e1);
        p1.add(t1);
        p2.add(e2);
        p2.add(t2);
        p3.add(b1);
 
        pack();
        setResizable(false);
        setLocationRelativeTo(null);
        setVisible(true);
 
        b1.addActionListener(new ActionListener()
                                 {
                                    public void actionPerformed(ActionEvent ev)
                                    {
                                        double meters = Double.parseDouble(t1.getText());
                                        double milimeters = meters * 1000;
                                        t2.setText(Double.toString(milimeters));
                                    }
 
                                 }
        );
 
    }
 
    public static void main(String args[])
    {
        Milimetri m = new Milimetri();
    }
 
}

Thank you for your help! i understand now what i have to do!