ciao

package valutaEspressione;

import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;


public class Calcolatrice { //DA COMPLETARE
	private static class FrontEnd extends JFrame implements ActionListener{
		private static final long serialVersionUID = 1L;
		JPanel q,p0,k,p1,p2,j = new JPanel();
		JTextField jtf;
		JButton zero,uno,due,tre,quattro,cinque,sei,sette,otto,nove,buh,history,
		diviso,per,piu,meno,pow,uguale,mod,punto,pa,pc,back,del = new JButton("0");
		public FrontEnd(){
			setTitle("Calcolatrice");
			setSize(500,250);
			setLocation(500,200);
			//...
			JPanel q=new JPanel();
			JTextField jtf=new JTextField("",35);
			jtf.addActionListener(this);
			q.add(jtf);
			JPanel p0=new JPanel();
			p0.setLayout( new GridLayout(2,1,5,5));
			p0.add(q,BorderLayout.NORTH);
			JPanel k=new JPanel();
			k.setLayout( new GridLayout(1,2,5,5));
			//...
			JPanel p1=new JPanel();
			p1.setLayout( new GridLayout(3,6,5,5) );
			JPanel p2=new JPanel();
			p2.setLayout( new GridLayout(1,2,5,5));
			JPanel j=new JPanel();
			j.setLayout(new GridLayout(1,3,5,5));
			//JButton buh= new JButton("?");
			//buh.addActionListener(this);
			//JButton history= new JButton("HISTORY");
			//history.addActionListener(this);
			//JButton sette=new JButton("7");
			//sette.addActionListener(this);
			//JButton otto=new JButton("8");
			//otto.addActionListener(this);
			//JButton nove=new JButton("9");
			//nove.addActionListener(this);
			//JButton diviso=new JButton("/");
			//diviso.addActionListener(this);
			//JButton quattro=new JButton("4");
			//quattro.addActionListener(this);
			//JButton cinque=new JButton("5");
			//cinque.addActionListener(this);
			//JButton sei=new JButton("6");
			//sei.addActionListener(this);
			//JButton per=new JButton("X");
			//per.addActionListener(this);
			//JButton uno=new JButton("1");
			//uno.addActionListener(this);
			//JButton due=new JButton("2");
			//due.addActionListener(this);
			//JButton tre=new JButton("3");
			//tre.addActionListener(this);
			//JButton meno=new JButton("-");
			//meno.addActionListener(this);
			//JButton zero=new JButton("0");
			//zero.addActionListener(this);
			//JButton punto=new JButton(",");
			//punto.addActionListener(this);
			//JButton uguale=new JButton("=");
			//uguale.addActionListener(this);
			//JButton piu=new JButton("+");
			//piu.addActionListener(this);
			//JButton back=new JButton("BACK");
			//back.addActionListener(this);
			//JButton del= new JButton("CLEAR");
			//del.addActionListener(this);
			//JButton pa= new JButton("(");
			//pa.addActionListener(this);
			//JButton pc=new JButton(")");
			//pc.addActionListener(this);
			//JButton mod=new JButton("%");
			//mod.addActionListener(this);
			//JButton pow=new JButton("EXP");
			//pow.addActionListener(this);

			//...
			j.add(zero); j.add(punto); j.add(mod);
			k.add(history); k.add(buh);
			p1.add(sette); p1.add(otto); p1.add(nove); p1.add(diviso); p1.add(back); p1.add(del);
			p1.add(quattro); p1.add(cinque); p1.add(sei); p1.add(per); p1.add(pa); p1.add(pc);
			p1.add(uno); p1.add(due); p1.add(tre); p1.add(meno); p1.add(piu); p1.add(pow);
			//...
			p0.add(k,BorderLayout.SOUTH);
			p2.add(j,BorderLayout.WEST);
			p2.add(uguale,BorderLayout.EAST);
			add( p0, BorderLayout.NORTH ); //aggiunta del pannello p alla JFrame
			add( p1, BorderLayout.CENTER);
			add( p2, BorderLayout.SOUTH);
			zero.addActionListener(this);
			}//costruttore
		public void actionPerformed(ActionEvent evt){
			if(evt.getSource()==zero) jtf.setText(jtf.getText()+"0");
			else if(evt.getSource()==uno) jtf.setText(jtf.getText()+"1");
			else if(evt.getSource()==due) jtf.setText(jtf.getText()+"2");
			else if(evt.getSource()==tre) jtf.setText(jtf.getText()+"3");

		}
	}//FrontEnd
	public static void main( String[] args ){
		FrontEnd fe=new FrontEnd();
		fe.setVisible(true);


	}
}