calculator.java

一个java计算器

//编制人员：秦星   学号：G0417015
package pack_calculator;
import java.awt.*;
import java.awt.event.*;

public class Calculator extends WindowAdapter implements ActionListener 
{
	static int tag1,tag2,tag3;
	static double nd1,nd2,nd3;
	static Double dtemp;
	static String ns1,ns2,ns3,op1,op2,op3;
	static TextField t;
	Frame f;
	//将String型字符变成double型数字
	public double TurnTodou(String str)
	{
		Double dou1 = new Double(0);
		Double dou2 = new Double(0);
	    dou2 = dou1.valueOf(str);
		double d = dou2.doubleValue();
		return d;
	}
	//将Double型数字变成String型字符
	public String TurnToStr(Double dou)
	{
		String str;
		double d = dou.doubleValue(); 
		str = dou.toString(d);
		return str;
	}
	//得到运算优先级比较数字
	public int CompareNum(String str)
	{
		int i=0;
		if(str.equals("+")==true||str.equals("-")==true){i=1;}
		if(str.equals("*")==true||str.equals("/")==true){i=2;}
		return i;
	    
	}
	//当遇到分母为零时的清零函数
	public void ClearText()
	{
		ns1="$";ns2="$";ns3="$";
		op1="$";op2="$";op3="$";
		nd1=0;nd2=0;nd3=0;
		tag1=0;tag2=0;tag3=0;	
		t.setText("E");
	}
	//检验计算结果是否为小数
	public int CheckFloat(String str)
	{
		int j=0;
	    for(int k=0;k<str.length();k++)
		{
			if(str.charAt(k)=='.') {j=1;break;}
			else {j=0;}
		}
		return j;
	}
	//主函数
	public static void run()
	{
		Calculator mcal = new Calculator();
		mcal.MyWindowShow();
	}
	public void MyWindowShow()
	{//变量初始化
		ns1=new String("$");ns2=new String("$");ns3=new String("$");
		op1=new String("$");op2=new String("$");op3=new String("$");
		nd1=0;nd2=0;nd3=0;
		tag1=0;tag2=0;tag3=0;	
		t=new TextField("0");
		t.setEnabled(false); 
	//窗体初始化
		int i=0;
		f = new Frame("MyCalculator!");
		Panel p = new Panel();
		t = new TextField("0");
		Button b[] = new Button[17];//"7","8","9","+","4","5","6","-","1","2","3","*","0",".","=","/","CLS"
		b[0] = new Button("7");b[1] = new Button("8");b[2] = new Button("9");b[3] = new Button("+");
		b[4] = new Button("4");b[5] = new Button("5");b[6] = new Button("6");b[7] = new Button("-");
		b[8] = new Button("1");b[9] = new Button("2");b[10] = new Button("3");b[11] = new Button("*");
		b[12] = new Button("0");b[13] = new Button(".");b[14] = new Button("=");b[15] = new Button("/");
		b[16] = new Button("CLS");

		f.add(t,"North");
		f.add(p,"Center");
		f.add(b[16],"South");
		p.setLayout(new GridLayout(4,4));
		for(i=0;i<=15;i++) {p.add(b[i]);}
		
		f.addWindowListener(this);//注册窗体兼听程序
		for(i=0;i<=16;i++) {b[i].addActionListener(this);}//注册按钮按动兼听程序
		
		f.setSize(300,250);
		f.setVisible(true);
	}
	//覆盖WindowAdapter类中的windowClosing()方法
	public void windowClosing(WindowEvent e) {f.setVisible(false);}
	//覆盖ActionListener接口中的actionPerformed()方法
    public void actionPerformed(ActionEvent e)
	{
		if(e.getActionCommand().equals(".")==true) {tag1++;}
		if(e.getActionCommand().equals(".")==false&&tag1>=2) {tag1=1;}
		if(e.getActionCommand().equals("CLS")==false)
		{   
			if(e.getActionCommand().equals(".")==true||e.getActionCommand().equals("0")==true||e.getActionCommand().equals("1")==true||e.getActionCommand().equals("2")==true||e.getActionCommand().equals("3")==true||e.getActionCommand().equals("4")==true||e.getActionCommand().equals("5")==true||e.getActionCommand().equals("6")==true||e.getActionCommand().equals("7")==true||e.getActionCommand().equals("8")==true||e.getActionCommand().equals("9")==true)
	        {//tag1限制一个浮点数中小数点个数只能为1；tag2限制一个浮点数的有效数字是16个；当输入一个新的运算符时其值自动回零
			    if(op1.equals("$")==true)//输入第一个运算数
				{   
					if(tag1<2&&tag2<=15)
					{
						if(ns1.equals("$")==true&&e.getActionCommand().equals(".")==true) {ns1="0"+e.getActionCommand();}
						else
						{
							if(ns1.equals("$")==true&&e.getActionCommand().equals(".")==false) {ns1=e.getActionCommand();}
							else
							{
							    if(ns1.equals("$")==true) {ns1=e.getActionCommand();}
								else 
								{
									if(ns1.equals("0")==true&&e.getActionCommand().equals("0")==true) {ns1="0";}  
									else 
									{
										if(ns1.equals("$")==false&&e.getActionCommand().equals(".")==true) 
										{   
											if(this.TurnTodou(ns1)==0){ns1="0.";tag3=0;}
											else {ns1=ns1+e.getActionCommand();}
										}  
										else 
										{
											if(tag3==1) {ns1=e.getActionCommand();tag3=0;}
											else 
											{
												if(ns1.equals("0")==true&&e.getActionCommand().equals("0")==false) {ns1=e.getActionCommand();}
												else{ns1=ns1+e.getActionCommand();}
											
											}
										}
									}
								}	
							}
						}
					}
					tag2++;
					t.setText(ns1);
				}
				if(op1.equals("$")==false&&op2.equals("$")==true)//输入第二个运算数
				{
					if(tag1<2&&tag2<=15)
					{
						if(ns2.equals("$")==true&&e.getActionCommand().equals(".")==true)
						{ns2="0"+e.getActionCommand();}
						else
						{
							if(ns2.equals("$")==true&&e.getActionCommand().equals(".")==false){ns2=e.getActionCommand();}
							else
							{
								if(ns2.equals("$")==true) {ns1=e.getActionCommand();}
								else 
								{
									if(ns2.equals("0")==true&&e.getActionCommand().equals("0")==true) {ns2="0";}  
									else {ns2=ns2+e.getActionCommand();}
							
								}
							}
						}
					}
					tag2++;
					t.setText(ns2);
				}
				if(op1.equals("$")==false&&op2.equals("$")==false)//输入第三个运算数
				{
					if(tag1<2&&tag2<=15)
					{
						if(ns3.equals("$")==true&&e.getActionCommand().equals(".")==true)
						{ns3="0"+e.getActionCommand();}
						else
						{
							if(ns3.equals("$")==true&&e.getActionCommand().equals(".")==false){ns3=e.getActionCommand();}
							else
							{
								if(ns3.equals("$")==true) {ns1=e.getActionCommand();}
								else 
								{
									if(ns3.equals("0")==true&&e.getActionCommand().equals("0")==true) {ns3="0";}  
									else {ns3=ns3+e.getActionCommand();}
							
								}
							}
						}
					}
					tag2++;
					t.setText(ns3);
				}
		    }
		    if(e.getActionCommand().equals("+")==true||e.getActionCommand().equals("-")==true||e.getActionCommand().equals("*")==true||e.getActionCommand().equals("/")==true)
		    {//利用堆栈的原理，根据优先级，进行计算，在只有+-*/四种运算时只有三个变量就可以储存相继的运算符
			    tag1=0;tag2=0;
				if(op1.equals("$")==true||ns2.equals("$")==true)//储存一个运算符时的计算
				{
					op1=e.getActionCommand();
					if(ns1.equals("$")==true){ns1="0";}
				}
				if(op1.equals("$")==false&&ns2.equals("$")==false&&ns3.equals("$")==true)//储存二个运算符时的计算
				{
					op2=e.getActionCommand();
					if(this.CompareNum(op1)>=this.CompareNum(op2))
					{
						nd1=this.TurnTodou(ns1);nd2=this.TurnTodou(ns2); 
						if(op1.equals("+")==true) {nd1=nd1+nd2;dtemp=new Double(nd1);ns1=this.TurnToStr(dtemp);}
						if(op1.equals("-")==true) {nd1=nd1-nd2;dtemp=new Double(nd1);ns1=this.TurnToStr(dtemp);}
						if(op1.equals("*")==true) {nd1=nd1*nd2;dtemp=new Double(nd1);ns1=this.TurnToStr(dtemp);}
						if(op1.equals("/")==true) 
						{
							if(nd2!=0) {nd1=nd1/nd2;dtemp=new Double(nd1);ns1=this.TurnToStr(dtemp);}
							else 
							{
								if(nd1==0) {ns1="1";}
								else {this.ClearText();}
							}
						}
						ns2="$";op1=op2;op2="$";
						t.setText(ns1);						
					}
				}
				if(op2.equals("$")==false&&ns3.equals("$")==false)//储存三个运算符时的计算
				{
					op3=e.getActionCommand();
					nd2=this.TurnTodou(ns2);nd3=this.TurnTodou(ns3);
					if(op2.equals("+")==true) {nd2=nd2+nd3;dtemp=new Double(nd2);ns2=this.TurnToStr(dtemp);}
					if(op2.equals("-")==true) {nd2=nd2-nd3;dtemp=new Double(nd2);ns2=this.TurnToStr(dtemp);}
					if(op2.equals("*")==true) {nd2=nd2*nd3;dtemp=new Double(nd2);ns2=this.TurnToStr(dtemp);}
					if(op2.equals("/")==true) 
					{
						if(nd3!=0) {nd2=nd2/nd3;dtemp=new Double(nd2);ns2=this.TurnToStr(dtemp);}
						else 
						{
							if(nd2==0) {ns2="1";}
							else {this.ClearText();}
						}
					}
					ns3="$";op2=op3;op3="$";
					if(this.CompareNum(op1)>=this.CompareNum(op2))
					{
						nd1=this.TurnTodou(ns1);nd2=this.TurnTodou(ns2); 
						if(op1.equals("+")==true) {nd1=nd1+nd2;dtemp=new Double(nd1);ns1=this.TurnToStr(dtemp);}
						if(op1.equals("-")==true) {nd1=nd1-nd2;dtemp=new Double(nd1);ns1=this.TurnToStr(dtemp);}
						if(op1.equals("*")==true) {nd1=nd1*nd2;dtemp=new Double(nd1);ns1=this.TurnToStr(dtemp);}
						if(op1.equals("/")==true) 
						{
							if(nd2!=0) {nd1=nd1/nd2;dtemp=new Double(nd1);ns1=this.TurnToStr(dtemp);}
							else 
							{
								if(nd1==0) {ns1="1";}
								else {this.ClearText();}
							}
						}
						ns2="$";op1=op2;op2="$";
						t.setText(ns1);						
					}					
				}
		    }
			if(e.getActionCommand().equals("=")==true)//输入等号时的计算
			{
				if(ns1.equals("$")==false&&ns2.equals("$")==true&&op1.equals("$")==false)
			    {
					nd1=this.TurnTodou(ns1);
					if(op1.equals("+")==true) {nd1=nd1+nd1;dtemp=new Double(nd1);ns1=this.TurnToStr(dtemp);}
					if(op1.equals("-")==true) {nd1=nd1-nd1;dtemp=new Double(nd1);ns1=this.TurnToStr(dtemp);}
					if(op1.equals("*")==true) {nd1=nd1*nd1;dtemp=new Double(nd1);ns1=this.TurnToStr(dtemp);}
					if(op1.equals("/")==true) {ns1="1";}
					op1="$";tag1=0;tag2=0;tag3=1;t.setText(ns1);
				}
				if(ns1.equals("$")==false&&op1.equals("$")==false&&ns2.equals("$")==false&&ns3.equals("$")==true)
			    {
					nd1=this.TurnTodou(ns1);nd2=this.TurnTodou(ns2); 
					if(op1.equals("+")==true) {nd1=nd1+nd2;dtemp=new Double(nd1);ns1=this.TurnToStr(dtemp);}
					if(op1.equals("-")==true) {nd1=nd1-nd2;dtemp=new Double(nd1);ns1=this.TurnToStr(dtemp);}
					if(op1.equals("*")==true) {nd1=nd1*nd2;dtemp=new Double(nd1);ns1=this.TurnToStr(dtemp);}
					if(op1.equals("/")==true) 
					{
						if(nd2!=0) {nd1=nd1/nd2;dtemp=new Double(nd1);ns1=this.TurnToStr(dtemp);}
						else 
						{
							if(nd1==0) {ns1="1";}
							else {this.ClearText();}
						}
					}
					ns2="$";op1="$";op2="$";tag1=0;tag2=0;tag3=1;t.setText(ns1);		
				}
				if(ns1.equals("$")==false&&op1.equals("$")==false&&ns2.equals("$")==false&&op2.equals("$")==false&&ns3.equals("$")==false)
			    {
					nd2=this.TurnTodou(ns2);nd3=this.TurnTodou(ns3); 
					if(op2.equals("+")==true) {nd2=nd2+nd3;dtemp=new Double(nd2);ns2=this.TurnToStr(dtemp);}
					if(op2.equals("-")==true) {nd2=nd2-nd3;dtemp=new Double(nd2);ns2=this.TurnToStr(dtemp);}
					if(op2.equals("*")==true) {nd2=nd2*nd3;dtemp=new Double(nd2);ns2=this.TurnToStr(dtemp);}
					if(op2.equals("/")==true) 
					{
						if(nd3!=0) {nd2=nd2/nd3;dtemp=new Double(nd2);ns2=this.TurnToStr(dtemp);}
						else 
						{
							if(nd2==0) {ns2="1";}
							else {this.ClearText();}
						}
					}
					ns3="$";op2="$";op3="$";
					nd1=this.TurnTodou(ns1);nd2=this.TurnTodou(ns2); 
					if(op1.equals("+")==true) {nd1=nd1+nd2;dtemp=new Double(nd1);ns1=this.TurnToStr(dtemp);}
					if(op1.equals("-")==true) {nd1=nd1-nd2;dtemp=new Double(nd1);ns1=this.TurnToStr(dtemp);}
					if(op1.equals("*")==true) {nd1=nd1*nd2;dtemp=new Double(nd1);ns1=this.TurnToStr(dtemp);}
					if(op1.equals("/")==true) 
					{
						if(nd2!=0) {nd1=nd1/nd2;dtemp=new Double(nd1);ns1=this.TurnToStr(dtemp);}
						else 
						{
							if(nd1==0) {ns1="1";}
							else {this.ClearText();}
						}
					}
					ns2="$";op1="$";op2="$";tag1=0;tag2=0;tag3=1;t.setText(ns1);													    	
				}
			}
		}
		else//清零
		{
		    this.ClearText(); 
			t.setText("0");
		}
	}
}