Javaゼミ第15回練習問題解答(加藤)

問１

import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import java.util.StringTokenizer;
/*
  <applet code="TextFieldEvents" width=400 height=200>
  </applet>
*/

public class Sample extends Applet 
implements ActionListener, TextListener, ItemListener {
  TextArea ta;
  TextField tf;
  int a,b;

  public void init() {
    tf = new TextField(20);
    tf.addActionListener(this);
    tf.addTextListener(this);
    ta = new TextArea(10, 20);
    add(tf);
    //add(ta);
    List list = new List();
    list.add("足し算");
    list.add("引き算");
    list.add("掛け算");
    list.add("割り算");
    list.addActionListener(this);
    list.addItemListener(this);
    add(list);
    add(ta);
  }

  public void actionPerformed(ActionEvent ae) {
	  String str = ae.getActionCommand();
	  StringTokenizer st = new StringTokenizer(str," ");
	  a = Integer.parseInt(st.nextToken());
	  b = Integer.parseInt(st.nextToken());
    tf.setText("");
  }

  public void textValueChanged(TextEvent te) {

  }

  public void itemStateChanged(ItemEvent ie) {
	    List list = (List)ie.getItemSelectable();
	    String str="";
	    if(list.getSelectedItem()=="足し算"){
	    	str = a + "と"+ b +"を足したものは、" + String.valueOf(a+b) + "\n";
	    }
	    if(list.getSelectedItem()=="引き算"){
	    	str = a + "と"+ b +"を引いたものは、" + String.valueOf(a-b) + "\n";
	    }
	    if(list.getSelectedItem()=="掛け算"){
	    	str = a + "と"+ b +"を掛けたものは、" + String.valueOf(a*b) + "\n";	
	    }
	    if(list.getSelectedItem()=="割り算"){
	    	str = a + "と"+ b +"を割ったものは、" + String.valueOf(a/b) + "\n";	
	    }
    	ta.append(str);	
	  }
}