calculator.java

一个简单的计算器!

import lundin.SymbolicMath.Eval;
import lundin.SymbolicMath.Derive;
import java.applet.Applet;
import java.util.*;
import java.awt.*;


public class Calculator extends Applet{


	Panel p = null;
	Panel p1 = null;
	Panel p2 = null;
	Panel p3 = null;
	Label lbl = null;
	Eval ev = null;
	Derive de = null;
	TextField tf = null;
	Button info = null;
	Button clear = null;
	Button equa = null;
	Button plus = null;
	Button minus = null;
	Button divide = null;
	Button mult = null;
	Button zerow,one,two,three,four,five,six,seven,eight,nine,point;
	Hashtable values = null;
	Font fo = null;
	FontMetrics fm = null; 
	
	
	

	public void init()
	{
	
		int color = 0x999966;
		GridBagLayout gridb = new GridBagLayout();
		GridBagLayout gridb2 = new GridBagLayout();
		GridBagLayout gridb3 = new GridBagLayout();
	    	GridBagConstraints constr = new GridBagConstraints();
		String temp = "";
	
		ev = new Eval();
		de = new Derive();
		values = new Hashtable();
		fo = new Font("Times Roman", Font.PLAIN, 9 );
		this.setFont( fo );
		fm = this.getFontMetrics( fo );

		p = new Panel();
		p1 = new Panel();
		p2 = new Panel();
		p3 = new Panel();
		tf = new TextField();
		
		info = new Button( "Info" );
		clear = new Button( "Clear" );
		plus = new Button( "+" );	
		minus = new Button( "-" );
		mult = new Button( "*" );
		divide = new Button( "/" );
		equa = new Button( "=" );
		point = new Button(".");
		zerow = new Button("0");
		one = new Button("1");
		two = new Button("2");
		three = new Button("3");
		four = new Button("4");
		five = new Button("5");
		six = new Button("6");
		seven = new Button("7");
		eight = new Button("8");
		nine = new Button("9");
	
		
		this.setBackground( new Color(color) );
		
		
		p2.setLayout( gridb );
		p2.setBackground( new Color(color) );
		p2.setForeground( Color.black );
		
		p3.setBackground( new Color(color) );
		p3.setForeground( Color.black );
		
		tf.setBackground( Color.white );
		tf.setForeground( Color.black );
		
		constr.fill = GridBagConstraints.NONE;
		constr.anchor = GridBagConstraints.CENTER;
		constr.gridx = 0;
		constr.gridy = 0;
		constr.ipadx = 3;
		constr.ipady = 3;
		gridb.setConstraints( seven , constr );
		
		p2.add( seven);
		
		constr.fill = GridBagConstraints.NONE;
		constr.anchor = GridBagConstraints.CENTER;
		constr.gridx = 1;
		constr.gridy = 0;
		gridb.setConstraints( eight , constr );
		
		p2.add( eight );
		
		constr.fill = GridBagConstraints.NONE;
		constr.anchor = GridBagConstraints.CENTER;
		constr.gridx = 2;
		constr.gridy = 0;
		gridb.setConstraints( nine , constr );
		
		p2.add( nine );
		
		
		constr.fill = GridBagConstraints.NONE;
		constr.anchor = GridBagConstraints.CENTER;
		constr.gridx = 3;
		constr.gridy = 0;
		
		gridb.setConstraints( plus , constr );
		
		p2.add( plus );
		
		constr.fill = GridBagConstraints.NONE;
		constr.anchor = GridBagConstraints.CENTER;
		constr.gridx = 0;
		constr.gridy = 1;
		gridb.setConstraints( four , constr );
		
		p2.add( four );
		
		constr.fill = GridBagConstraints.NONE;
		constr.anchor = GridBagConstraints.CENTER;
		constr.gridx = 1;
		constr.gridy = 1;
		gridb.setConstraints( five , constr );
		
		p2.add( five );
		
		constr.fill = GridBagConstraints.NONE;
		constr.anchor = GridBagConstraints.CENTER;
		constr.gridx = 2;
		constr.gridy = 1;
		gridb.setConstraints( six , constr );
		
		p2.add( six );
		
		constr.fill = GridBagConstraints.NONE;
		constr.anchor = GridBagConstraints.CENTER;
		constr.gridx = 3;
		constr.gridy = 1;
		
		gridb.setConstraints( minus , constr );
		
		p2.add( minus );
		
		constr.fill = GridBagConstraints.NONE;
		constr.anchor = GridBagConstraints.CENTER;
		constr.gridx = 0;
		constr.gridy = 2;
		gridb.setConstraints( one , constr );
		
		p2.add( one );
		
		constr.fill = GridBagConstraints.NONE;
		constr.anchor = GridBagConstraints.CENTER;
		constr.gridx = 1;
		constr.gridy = 2;
		gridb.setConstraints( two , constr );
		
		p2.add( two );


		
		constr.fill = GridBagConstraints.NONE;
		constr.anchor = GridBagConstraints.CENTER;
		constr.gridx = 2;
		constr.gridy = 2;
		gridb.setConstraints( three , constr );
		
		p2.add( three );
		
		
		constr.fill = GridBagConstraints.NONE;
		constr.anchor = GridBagConstraints.CENTER;
		constr.gridx = 3;
		constr.gridy = 2;
		
		gridb.setConstraints( mult , constr );
		
		p2.add( mult );
		
		constr.fill = GridBagConstraints.NONE;
		constr.anchor = GridBagConstraints.CENTER;
		constr.gridx = 0;
		constr.gridy = 3;
		gridb.setConstraints( equa , constr );
		
		p2.add( equa );
		
		constr.fill = GridBagConstraints.NONE;
		constr.anchor = GridBagConstraints.CENTER;
		constr.gridx = 1;
		constr.gridy = 3;
		gridb.setConstraints( zerow , constr );
		
		p2.add( zerow );
		
		constr.fill = GridBagConstraints.NONE;
		constr.anchor = GridBagConstraints.CENTER;
		constr.gridx = 2;
		constr.gridy = 3;
		gridb.setConstraints( point , constr );
		
		p2.add( point );
		
		
		constr.fill = GridBagConstraints.NONE;
		constr.anchor = GridBagConstraints.CENTER;
		constr.gridx = 3;
		constr.gridy = 3;
		
		gridb.setConstraints( divide , constr );
		
		p2.add( divide );
		
		
		p1.setLayout( gridb3 );
		p1.setBackground( new Color(color) );
		p1.setForeground( Color.black );
		
	
	
		constr.fill = GridBagConstraints.NONE;
		constr.anchor = GridBagConstraints.CENTER;
		constr.gridx = 0;
		constr.gridy = 0;
		gridb3.setConstraints( clear , constr );
		
		p1.add( clear );
		
		constr.fill = GridBagConstraints.NONE;
		constr.anchor = GridBagConstraints.CENTER;
		constr.gridx = 1;
		constr.gridy = 0;
		gridb3.setConstraints( info , constr );
		
		p1.add( info );
	
	
		p.setLayout( gridb2 );
		p.setBackground( new Color(color) );
		p.setForeground( Color.black );
		
		
		constr.fill = GridBagConstraints.HORIZONTAL;
		constr.anchor = GridBagConstraints.CENTER;
		constr.gridx = 0;
		constr.gridy = 0;
		gridb2.setConstraints( tf , constr );
		
		p.add( tf );
		
		constr.fill = GridBagConstraints.HORIZONTAL;
		constr.anchor = GridBagConstraints.CENTER;
		constr.gridx = 0;
		constr.gridy = 1;
		gridb2.setConstraints( p2 , constr );
		
		
		p.add( p2 );
		
		constr.fill = GridBagConstraints.NONE;
		constr.anchor = GridBagConstraints.CENTER;
		constr.gridx = 0;
		constr.gridy = 2;
		gridb2.setConstraints( p1 , constr );
		
		p.add( p1 );
		
		constr.fill = GridBagConstraints.NONE;
		constr.anchor = GridBagConstraints.CENTER;
		constr.gridx = 0;
		constr.gridy = 3;
		gridb2.setConstraints( p3 , constr );
		
		p.add( p3 );
		
		this.add( p );
		
		try{
			System.out.println("\n\nApplet Calculator Made by Patrik Lundin, [e-mail]\n\n");	
		}catch(Exception ex){}
		
	}
	
	
	void
	evaluate()
	{
		String temp = "";
		String tmp = "";
		int ind1 = 0;
		int ind2 = 0;
		
		try{
			
			tmp = prepare( tf.getText().toLowerCase() );
			
			if( tmp.equals("") ){
				return;
			}