calculatordemo.java

这是一个用java编写的简单计算器

import java.awt.Button;
import java.awt.Color;
import java.awt.Container;
import java.awt.Event;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.Panel;

import javax.swing.JFrame;
import javax.swing.JTextField;

 
public class CalculatorDemo extends JFrame{

	/**
	 * @param args
	 */
	JTextField answerText;
	Button pointButton,equalButton,plusButton,minusButton,clearButton,multiButton,divisionButton;
	Button[] b=new Button[10];
	String currentOp ,preOp;
	String foreText,backText;
	boolean isFloat=false;
	public CalculatorDemo()
	{	super("计算器");
		setSize(400,400);
		
		Container container=getContentPane();
		setVisible(true);
		Panel panel1=new Panel();
		Panel panel2=new Panel();
		Panel panel3=new Panel();
		currentOp=new String("");
		preOp=new String("");
		foreText=new String("");
		backText=new String("");
		answerText=new JTextField(8);
		container.setBackground(Color.lightGray);
		//container.setForeground(Color.blue);
		for(int i=9;i>=0;i--)
		{
			b[i]=new Button(Integer.toString(i));
			panel2.add(b[i]);
		
		}
		pointButton=new Button(".");
		equalButton=new Button("=");
		clearButton=new Button("清除");
		clearButton.setForeground(Color.red);
		divisionButton=new Button("/");
		divisionButton.setForeground(Color.red);
		multiButton=new Button("*");
		plusButton=new Button("+");
		plusButton.setForeground(Color.red);
		minusButton=new Button("-");
		minusButton.setForeground(Color.red);
		container.setLayout(new FlowLayout());
		panel1.setLayout(new FlowLayout());
		panel2.setLayout(new GridLayout(4,3));
		panel3.setLayout(new GridLayout(4,1));
		panel1.add(answerText);
		panel1.add(clearButton);
		panel2.add(pointButton);
		panel2.add(equalButton);
		panel3.add(plusButton);
		panel3.add(minusButton);
		panel3.add(multiButton);
		panel3.add(divisionButton);
		
		container.add(panel1);
		container.add(panel2);
		container.add(panel3);
		
	}
	
	/*public boolean action(Event e,Object o)
	{
		String s=new String("");
		for(int i=0;i<10;i++)
		{
			if(e.target==b[i]||e.target==pointButton)
			{
				if(e.target!=pointButton)
				{
					s=(String)o;
					doForeText(s);
					
				}
				if((e.target==pointButton)&&(!isFloat))
				{
					isFloat=true;
					s=(String)o;
					if(foreText.equals(""))
					{
						foreText+="0.";
					}
					else
					{
						doForeText(s);
					}
				}
			}
		}
		if(e.target==clearButton)
		{
			doClear();
			
		}
		if((e.target==multiButton)||(e.target==divisionButton)||(e.target==plusButton)||(e.target==minusButton))
		{
			if(foreText!="")
			{
				currentOp=(String)o;
				doOprator();
				
			}
			else
			{
				preOp=(String)o;
			}
		}
		if(e.target==equalButton)
		{
			doOprator();
			
		}
		return true;
	}
	
	public void doOprator()
	{
		double dFore,dBack;
		Double d;
		if(preOp.equals(""))
		{
			backText=foreText;
			foreText="";
			answerText.setText(backText);
		}
		else
		{
			dFore=(new Double(foreText)).doubleValue();
			dBack=(new Double(backText)).doubleValue();
			foreText="";
			backText=answerText.getText();
			if(preOp.equals("+"))
			{
				d=new Double((dBack+dFore));
				answerText.setText(d.toString());
				backText=d.toString();
				
			}
			if(preOp.equals("-"))
			{
				d=new Double((dBack-dFore));
				answerText.setText(d.toString());
				backText=d.toString();
				
			}
			if(preOp.equals("*"))
			{
				d=new Double((dBack*dFore));
				answerText.setText(d.toString());
				backText=d.toString();
				
			}
			if(preOp.equals("/"))
			{	if(dFore==0)
				{
					answerText.setText("除数不能为0");
					return;
				}						
				d=new Double((dBack/dFore));
				answerText.setText(d.toString());
				backText=d.toString();
				
			}
			
		}
		preOp=currentOp;
	}
	public void doForeText(String s)
	{
		foreText+=s;
		answerText.setText(foreText);
	}
	public void doBackText(String s)
	{	
		backText=foreText;
		foreText="";
		answerText.setText(foreText);
	}

		public void doClear()
		{
			currentOp="";
			preOp="";
			foreText="";
			backText="";
			isFloat=false;
			answerText.setText("");
		}*/

	
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		CalculatorDemo c=new CalculatorDemo();
	}

}