java课程设计之计算器

import javax.swing.*; import java.awt.*; import java.awt.event.*; public class Calculater extends JFrame implements ActionListener{ JTextField x; String preOperater=""; double sum=0; public Calculater(String title){ super(title); Container c=getContentPane(); c.setLayout(new BorderLayout()); x=new JTextField(50); c.add("North",x); String buttoned[]={"1","2","3","Backspace","=","4","5","6","+","-","7","8","9","*", "/","o","."}; JPanel operatePanel=new JPanel(); operatePanel.setLayout(new GridLayout(4,5,10,10)); for(int k=0;k<buttoned.length;k++) { JButton b=new JButton(buttoned[k]); operatePanel.add(b); b.addActionListener(this); } c.add("Center",operatePanel); this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); } void doOperation(){ double m=Double.parseDouble(x.getText()); if(preOperater.equals(""))sum=m; if(preOperater.equals("+"))sum=sum+m; if(preOperater.equals("-"))sum=sum-m; if(preOperater.equals("*"))sum=sum*m; if(preOperater.equals("/"))sum=sum/m; } public void actionPerformed(ActionEvent e){ String currentop=e.getActionCommand(); try{ if(Character.isDigit(currentop.charAt(0))){ x.setText(x.getText()+currentop); } else if (currentop.equals(".")){ String s=x.getText(); if(s.indexOf(".")==-1) { x.setText(s+"."); } } else if(currentop.equals("=")){ doOperation(); if(sum==(int)sum) x.setText(""+(int)sum); else x.setText(""+sum); preOperater=""; } else if(currentop.equals("Backspace")){ sum=0; x.setText(""); preOperater=""; } else{ doOperation(); x.setText(""); preOperater=currentop; } }catch(Exception ex){sum=0;x.setText("");} x.requestFocus(); } public static void main(String []a){ JFrame x=new Calculater("Culculater"); x.setSize(520,200); x.setVisible(true); } }