java面向对象课程代码

import java.awt.*; import java.awt.event.*; import java.applet.*; public class ExceptionApplet extends Applet implements ActionListener { Label L1,L2; TextField tf1,tf2; String answerStr; double d1,d2; public void init( ) { L1=new Label("请输入0到100之间的整数"); add(L1); tf1=new TextField(6); add(tf1); tf2=new TextField(6); add(tf2); L2=new Label("两数相除的结果： "); add(L2); tf1.addActionListener(this); tf2.addActionListener(this); } public void actionPerformed(ActionEvent evt) { try { d1=Double.valueOf(tf1.getText( )).doubleValue( ); d2=Double.valueOf(tf2.getText( )).doubleValue( ); // valueOf(String s) 可能抛出异常 NumberFormatException L2.setText("两数相除的结果： "+Result( )); // 调用 Result( ) 方法可能抛出 NumberRangeException 异常 } catch(NumberFormatException e) { answerStr="输入的必须是数字"; L2.setText(answerStr); } catch(NumberRangeException ee) { answerStr=ee.getMessage( ); L2.setText(answerStr); } repaint( ); } public double Result( ) throws NumberRangeException { double answer=0; try { if((d1<0)||(d2<0)||(d1>100)||(d2>100)) { NumberRangeException ee=new NumberRangeException("输入的数字不在指定的范围！请重新输入。"); throw ee; } answer=d1/d2; } catch(ArithmeticException eee) { answerStr=eee.toString( ); } return answer; } } class NumberRangeException extends Exception { NumberRangeException(String msg) { super(msg); } //子类调用父类的带参数的构造函数 }