java_4.java

里面有我的JAVA实验和一些教程

import java.applet.*;
import javax.swing.*;
import java.awt.*; 
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class calculator extends JApplet implements ActionListener
{
	Frame frm;
	JTextField txt;
	JMenuItem itmcpy;
	JMenuItem itmpas;
	JMenuItem itmabout;
	JMenuItem itmart;
	int yuna;
	String tf;
	String g;
	int key = 0;
	double yun=0;
	public void init()
	{
		
		frm=new Frame("计算器");
		
		frm.setLayout(null);
		frm.setSize(265,248);
		frm.setBackground(Color.LIGHT_GRAY);
		JMenuBar menu=new JMenuBar();
		menu.setSize(265, 20);
		menu.setLocation(0, 30);
		frm.add(menu);
		JMenu fileMenu=new JMenu("编辑");
		JMenu filehelp=new JMenu("帮助");
		menu.add(fileMenu);
		menu.add(filehelp);
		itmcpy=new JMenuItem("复制");
		itmcpy.addActionListener(this);
		itmpas=new JMenuItem("粘贴");
		itmpas.addActionListener(this);
		fileMenu.add(itmcpy);
		fileMenu.add(itmpas);
		itmart=new JMenuItem("帮助主题");
		itmart.addActionListener(this);
		itmabout=new JMenuItem("关于");	
		itmabout.addActionListener(this);
		filehelp.add(itmart);
		filehelp.add(itmabout);		
		
		txt=new JTextField(20);
		txt.setSize(252, 21);
		txt.setLocation(6, 52);
		txt.setHorizontalAlignment(txt.RIGHT);
		frm.add(txt);
		txt.addActionListener(this);
		
		JButton btnc=new JButton("C");
		btnc.setSize(58,28);
		btnc.setLocation(193,76);
		frm.add(btnc);
		btnc.addActionListener(this);
		
		JButton btnce=new JButton("CE");
		btnce.setSize(65,28);
		btnce.setLocation(123,76);
		frm.add(btnce);	
		btnce.addActionListener(this);
		
		JButton btnesc=new JButton("Backspace");
		btnesc.setSize(106,28);
		btnesc.setLocation(12,76);
		frm.add(btnesc);
		btnesc.addActionListener(this);
		
		JButton btnsqr=new JButton("sqrt");
		btnsqr.setSize(60,28); 
		btnsqr.setLocation(190,110);
		frm.add(btnsqr);
		btnsqr.addActionListener(this);
		
		JButton btnm=new JButton("/");
		btnm.setSize(38,28);
		btnm.setLocation(149,110);
		frm.add(btnm);
		btnm.addActionListener(this);
		
		JButton btn9=new JButton("9");
		btn9.setSize(42,28);
		btn9.setLocation(105,110);
		frm.add(btn9);
		btn9.addActionListener(this);

		JButton btn8=new JButton("8");
		btn8.setSize(42,28);
		btn8.setLocation(60,110);
		frm.add(btn8);
		btn8.addActionListener(this);
		
		JButton btn7=new JButton("7");
		btn7.setSize(42,28);
		btn7.setLocation(14,110);
		frm.add(btn7);
		btn7.addActionListener(this);
		
		JButton btn4=new JButton("4");
		btn4.setSize(42,28);
		btn4.setLocation(14,140);
		frm.add(btn4);
		btn4.addActionListener(this);
		
		JButton btn5=new JButton("5");
		btn5.setSize(42,28);
		btn5.setLocation(60,140);
		frm.add(btn5);
		btn5.addActionListener(this);
		
		JButton btn6=new JButton("6");
		btn6.setSize(42,28);
		btn6.setLocation(105,140);
		frm.add(btn6);
		btn6.addActionListener(this);
		
		JButton btnn=new JButton("*");
		btnn.setSize(39,28);
		btnn.setLocation(150,140);
		frm.add(btnn);
		btnn.addActionListener(this);
		
		JButton btnl=new JButton("%");
		btnl.setSize(58,28);
		btnl.setLocation(192,140);
		frm.add(btnl);
		btnl.addActionListener(this);
		
		JButton btnk=new JButton("1/x");
		btnk.setSize(58,28);
		btnk.setLocation(192,170);
		frm.add(btnk);
		btnk.addActionListener(this);
		
		JButton btnv=new JButton("-");
		btnv.setSize(39,28);
		btnv.setLocation(150,170);
		frm.add(btnv);
		btnv.addActionListener(this);
		
		JButton btn3=new JButton("3");
		btn3.setSize(42,28);
		btn3.setLocation(105,170);
		frm.add(btn3);
		btn3.addActionListener(this);
		
		JButton btn2=new JButton("2");
		btn2.setSize(42,28);
		btn2.setLocation(60,170);
		frm.add(btn2);
		btn2.addActionListener(this);
		
		JButton btn1=new JButton("1");
		btn1.setSize(42,28);
		btn1.setLocation(14,170);
		frm.add(btn1);
		btn1.addActionListener(this);
		
		JButton btn0=new JButton("0");
		btn0.setSize(42,28);
		btn0.setLocation(14,200);
		frm.add(btn0);
		btn0.addActionListener(this);
		
		JButton btnq=new JButton("+/-");
		btnq.setSize(50,28);
		btnq.setLocation(60,200);
		frm.add(btnq);
		btnq.addActionListener(this);
		
		JButton btna=new JButton(".");
		btna.setSize(40,28);
		btna.setLocation(112,200);
		frm.add(btna);
		btna.addActionListener(this);
		
		JButton btnb=new JButton("+");
		btnb.setSize(42,28);
		btnb.setLocation(155,200);
		frm.add(btnb);
		btnb.addActionListener(this);
		
		JButton btne=new JButton("=");
		btne.setSize(50,28);
		btne.setLocation(200,200);
		frm.add(btne);
		btne.addActionListener(this);
		
		
		frm.setVisible(true);
	}
	
	 public void actionPerformed(ActionEvent e)
	 {
		 int i;
		 String s = e.getActionCommand();  
		 tf=txt.getText().trim();
		 int l = txt.getText().trim().length();
		 if(e.getSource()==itmcpy)
		 {
			 txt.copy();
		 }
		 else if(e.getSource() == itmpas)
		 {
			 txt.setText("");
			 txt.paste();
		 }
		 else if(e.getSource() == itmabout)
		 {
			 txt.setText("" + "0400310506 陈旭");
		 }
		 else if(e.getSource() ==itmart)
		 {
			 txt.setText("" + "仿Windoos XP下的计算器");
		 }
		 if(s.equals("."))
		 {
			 for (int o = 0; o < l; o++) 
			 {
			     if ('.' == tf.charAt(o)) 
			     {
			      txt.setText("已经输入'.'不能重复输入");
			     } 
			     else 
			     {
			      txt.setText(txt.getText() + '.');
			     }
			     
			  }
		 }
		 for(i=0;i<=9;i++)
			 if(s.equals("" + i))
			 {
				 if(g!="")
				{
					 txt.setText("");
					 txt.setText("" + e.getActionCommand());
					 g = "";
				}
				 else txt.setText("" + txt.getText() + e.getActionCommand());
						 
			 }
				 
		 if(s.equals("Backspace"))
		 {
			 yuna = txt.getText().trim().length();
			 txt.setText(txt.getText().trim().substring(0,yuna - 1));
		 }
		 else if(s.equals("CE"))
		 {
			 txt.setText("0");
		 }
		 else if(s.equals("C"))
		 {
			 txt.setText("0");
			 yun = 0;
			 key = 0;
		 }
		 else if(s.equals("+"))
		 {
			 yun = Double.parseDouble(txt.getText().trim());
			 key = 1;
			 g = "+";
		 }
		 else if(s.equals("-"))
		 {
			 yun = Double.parseDouble(txt.getText().trim());
			 key = 2;
			 g = "-";
		 }
		 else if(s.equals("*"))
		 {
			 yun = Double.parseDouble(txt.getText().trim());
			 key = 3;
			 g = "*";
		 }
		 else if(s.equals("/"))
		 {
			 yun = Double.parseDouble(txt.getText().trim());
			 key = 4;
			 g = "/";
		 }
		 else if(s.equals("%"))
		 {
			 yun = (Double.parseDouble(txt.getText().trim())) / 100;
			 g = "%";
			 txt.setText("" +yun);
		 }
		 else if(s.equals("1/x"))
		 {
			 if(Double.parseDouble(txt.getText().trim())!=0)
			 {
			 yun = 1 / (Double.parseDouble(txt.getText().trim()));
			 g = "1/x";
			 txt.setText("" + yun);
			 }
			 else txt.setText("" + "0不能求倒数");
		 }
		 else if(s.equals("+/-"))
		 {
			 yun = - (Double.parseDouble(txt.getText().trim()));
			 g = "+/-";
			 txt.setText("" + yun);
		 }
		 else if(s.equals("sqrt"))
		 {
			 yun = Math.sqrt(Double.parseDouble(txt.getText().trim()));
			 g = "sqrt";
			 txt.setText("" + yun);
		 }
		 else if(s.equals("="))
		 {
			 switch(key)
			 {
			 case 1:
				 yun += Double.parseDouble(txt.getText().trim());	
				 txt.setText("" + yun);
				 break;
			 case 2:
				 yun -= Double.parseDouble(txt.getText().trim());	
				 txt.setText("" + yun);
				 break;
			 case 3:
				 yun *= Double.parseDouble(txt.getText().trim());	
				 txt.setText("" + yun);
				 break;
			 case 4:
				 if(Double.parseDouble(txt.getText().trim()) == 0)
				{
					 yun=0;
					 txt.setText("除数不能为空!");
				}
				 
				 else
					 {
					 yun /= Double.parseDouble(txt.getText().trim());	 
					 
				 	 txt.setText("" + yun);
					 }
				 break;
			 }
			 g = "e";
				 
		 }
	 }



}