Question

Is there a lib that can build a simple GUI by looking at a class or method signature?

For Example:

class MyMath{
    public static double sqrt(double d){
         //impl
    }
}       

To

So that when the button is clicked the method is invoked and the result is shown.

Do you know any examples of something like that in Java or other languages?

thanks

Answer 1

I coded a very basic example, which shows how this can be achieved using a few lines reflection code and little swing. Maybe init() should return the number of methods found for use in the GridLayout, then it would be more dynamic.

import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.lang.reflect.Method;
import java.util.HashMap;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextField;

public class MathPanel extends JFrame {

    public static double sqrt(double d) {
        return Math.sqrt(d);
    }

    public static double sin(double d) {
        return Math.sin(d);
    }

    public static double cos(double d) {
        return Math.cos(d);
    }

    class Item implements ActionListener {
        JTextField result = new JTextField();
        JTextField param = new JTextField();
        JButton button;
        Method m;
        public Item(JFrame frame,String name, Method m) {
            button = new JButton(name);
            button.addActionListener(this);
            this.m = m;
            frame.getContentPane().add(param);
            frame.getContentPane().add(button);
            frame.getContentPane().add(result);
        }

        public void actionPerformed(ActionEvent e) {
            String cmd  = e.getActionCommand();
            Item item = map.get(cmd);
            try {
                double dbl = Double.parseDouble(item.param.getText());
                Object invoke = item.m.invoke(this, dbl);
                item.result.setText("" + invoke );
            } 
            catch (Exception x) {
                x.printStackTrace();
            }
        }
    }

    HashMap<String,Item>map = new HashMap<String, Item>(); 


    public MathPanel() {
        setLayout(new GridLayout(3,3));
        setTitle("Test");
        setSize(400, 100);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
    }

    private void init() {
        try {
            Method[] allMethods = MathPanel.class.getDeclaredMethods();
            for (Method m : allMethods) {
                String mname = m.getName();
                Class<?> returnType = m.getReturnType();
                if ( returnType.getName().equals("double")) {
                    Item item = new Item(this,mname,m);
                    map.put(mname,item);
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        MathPanel mp = new MathPanel();
        mp.init();
    }
}