Java-ohjelmointikielen perusteet

Java-ohjelmointiympäristön asentaminen

Asenna Java-ohjelmointiympäristö. Ensin Java development Kit, sitten Java api documentation ja lopuksi JCreator tai jokin muu IDE.

Esimerkit

Käyttöliittymä

import java.applet.*;
import java.awt.*;
import java.awt.event.*;

class Ala {
	private int x,y,z;
	
	public void setAla(String x, String y){
		this.x = Integer.valueOf(x);
		this.y = Integer.valueOf(y);
		z = this.x * this.y;
	}
	public String getAla(){
		return String.valueOf(z);
	}
}
class Suorakulmio {
	private int x,y;
	void piirra(String x, String y, Graphics g) {
		this.x=Integer.valueOf(x);
		this.y=Integer.valueOf(y);
		g.drawRect(200,50,this.x,this.y);
	}
}

public class Kayttoliittyma extends Applet implements ActionListener {

   TextField tx, ty;
   Label tz;
   Button laske;
   Ala ala = new Ala();
   Suorakulmio ruutu = new Suorakulmio();
 
   public void init () {
     add(tx = new TextField());
     add(ty = new TextField());
     add(tz = new Label(""));
     add(laske = new Button("Ala"));
     laske.addActionListener(this);
   }

   public void paint(Graphics g) {
     tx.reshape(20, 20, 80, 20);
     ty.reshape(20, 40, 80, 20);
     tz.reshape(20, 60, 80, 20);
     laske.reshape(20, 80, 60, 20);
     ruutu.piirra(tx.getText(),ty.getText(),g);

   }

    public void actionPerformed(ActionEvent e) {
     if (e.getActionCommand().equals("Ala")){
	ala.setAla(tx.getText(),ty.getText());
	tz.setText(ala.getAla());
        repaint();
     }
   }
}
 

 

 

Runko

/**
 * @(#)Merkkijonot.java
 *
 * Merkkijonot Applet application
 *
 * @author
 * @version 1.00 2009/10/29
 */
 
import java.applet.*;
import java.awt.*;
import java.awt.event.*;

public class Merkkijonot extends Applet implements ActionListener {

	TextField tx;
	Label lx;
	Button ok;
	String x,y;
	
	public void init () {
		add(tx = new TextField());
		add(lx = new Label(""));
		add(ok = new Button("Ok"));
		ok.addActionListener(this);
	}

	public void paint(Graphics g) {
		tx.reshape(40, 20, 100, 20);
		lx.reshape(40, 40, 180, 20);
		ok.reshape(40,60,40,20);
	}

	public void actionPerformed(ActionEvent e) {
		if (e.getActionCommand().equals("Ok")){
			x = tx.getText();
			lx.setText(x);
			tx.setText("");
			tx.requestFocus();
		}	 
		repaint();
	}
}