java自制计算器（加减乘除 清空 退位 支持小数 括号）

首先建了一个JFrame的子类Show，在这个子类里面建了一个JPanel的内部子类MyPanel,Show显示的就是MyPanel的内容。通过画线，每次线颜色的rgb根据循环的i值做出相应的改变，从而实现了背景的渐变。后面根据一些Show的一些属性开始画网格，并且通过主函数的监听事件传入的坐标，在实现按键的效果（响应位置重画其它颜色）。根据位置把对应的符号传入Deal类进行运行。最后MyPanel画上Deal上的有关值的属性。

Main类就只要是设置号监听事件，传入被点击的坐标。刚开始使用的是mouseClick  但发现如果按下和抬起的坐标不一直，则这次点击无效，造成一种卡顿的假想。所以我用了mousePressed和mouseReleased这两个方法。

Deal类就是用于处理计算，Change方法是存入数值，防止非法输入。最麻烦的就是中缀转换为后缀的那个算法。

中缀转换为后缀思路请见：http://blog.csdn.net/in_clude/article/details/53146981

计算机器效果图

项目下载链接：http://download.csdn.net/detail/in_clude/9681337

代码如下

package yhz;import java.awt.Color;import java.awt.Graphics;import java.awt.event.MouseAdapter;import java.awt.event.MouseEvent;public class Main {public static void main(String args[]){final Show show=new Show();show.addMouseListener(new MouseAdapter(){public void mousePressed(MouseEvent e) {// TODO Auto-generated method stubsuper.mousePressed(e);int tx=e.getY()-show.mDivHeight/2;int ty=e.getX();if(tx>show.mDivision){show.mSelectX=(tx-show.mDivision)/show.mDivHeight;show.mSelectY=ty/show.mDivWidth;}show.repaint();}public void mouseReleased(MouseEvent e) {// TODO Auto-generated method stubsuper.mouseReleased(e);show.mSelectX=-1;show.mSelectY=-1;show.repaint();}});}}

package yhz;import java.awt.*;import javax.swing.*;public class Show extends JFrame {public int mDivision;//按钮与显示的分界线public int mDivWidth;//每个小格的宽public int mDivHeight; //每个小格的高public int[] mDivX = new int[10];//存每个小格左上角的x坐标public int[] mDivY = new int[10];//存每个小格左上角的y坐标public int mSelectX;public int mSelectY;public char [][] mSign = {{'C','<','(',')'},{'1','2','3','+'},{'4','5','6','-'},{'7','8','9','×'},{'.','0','=','÷'}};public Deal mDeal = new Deal();public Show(){setTitle("小智的计算器");setSize(90*3,160*3);this.getContentPane().add(new MyPanel());setVisible(true);setResizable(false);setLocation(400,100);mSelectX=-1;mSelectY=-1;}public class MyPanel extends JPanel{private int flag=0;protected void paintComponent(Graphics g) {// TODO Auto-generated method stubsuper.paintComponent(g);/** * 存储位置 */if(flag==0){mDivision=this.getWidth()*9/16-30;for(int i=0;i<6;i++){mDivX[i]=mDivision+(this.getHeight()-mDivision)*i/5;}for(int i=0;i<5;i++){mDivY[i]=this.getWidth()*i/4;}mDivHeight=(this.getHeight()-mDivision)/5; //5行mDivWidth=this.getWidth()/4; //4列flag=1;}/** * 下面开始绘图 *///背景for(int i=0;i<mDivision;i++){Color myColor = new Color(255,200,i/2);g.setColor(myColor);g.drawLine(0, i, this.getWidth(), i);}for(int i=mDivision;i<this.getHeight();i++){Color myColor = new Color(250-i/3,200-i/3,i/3);g.setColor(myColor);g.drawLine(0, i, this.getWidth(), i);}//按键效果if(mSelectX!=-1&&mSelectY!=-1){mDeal.Change(mSign[mSelectX][mSelectY]);for(int i=mDivX[mSelectX];i<=mDivX[mSelectX]+mDivHeight;i++){Color myColor = new Color(255,200,0);g.setColor(myColor);g.drawLine( mDivY[mSelectY], i, mDivY[mSelectY]+mDivWidth,i);}}g.setColor(Color.white);//网格for(int i=0;i<5;i++){g.drawLine(0, mDivX[i], this.getWidth(), mDivX[i]);}for(int i=1;i<=4;i++){g.drawLine(mDivY[i], mDivision, mDivY[i], this.getHeight());}//绘字for(int i=0;i<5;i++){for(int j=0;j<4;j++){g.drawString(String.valueOf(mSign[i][j]), mDivY[j]+mDivWidth/2-2, mDivX[i]+mDivHeight/2+5); //-2  +5是根据显示进行的微调}}Font font = new Font("Arial", Font.PLAIN, 29);g.setFont(font);if(mDeal.mText==""){g.drawString(mDeal.mAns, this.getWidth()-this.getFontMetrics(font).stringWidth(mDeal.mAns)-5, mDivision*2/3);}else g.drawString(mDeal.mText, this.getWidth()-this.getFontMetrics(font).stringWidth(mDeal.mText)-5, mDivision*2/3);Font font1 = new Font("Arial", Font.PLAIN, 16);g.setFont(font1);String str = new String();for(int i=0;i<mDeal.mDetailPos;i++){str+=mDeal.mTextDetail[i];}g.drawString(str, this.getWidth()-this.getFontMetrics(font1).stringWidth(str), mDivision/3);}}}

package yhz;import java.util.Stack;public class Deal {public String mText = new String();public String[] mTextDetail = new String[100];//用数组方便后缀表达式那儿放入栈中public int mDetailPos;public String mAns = new String();private int mLeftBracketNum;private String[] mSuffix =new String[105];private int mSuffixPos;private Stack mTemp =new Stack();public Deal(){mLeftBracketNum=0;mDetailPos=0;mAns="0";mText="";}public void Change(char c){mAns="0";if(c<='9'&&c>='0'){if(mDetailPos>0){if(mTextDetail[mDetailPos-1].equals(")")==false)mText+=c;}else mText+=c;}else if(c=='+'||c=='-'||c=='×'||c=='÷'){if(mText!=""){if(mText.substring(mText.length()-1, mText.length()).equals("."))//确保末尾不能有小数点{mText=mText.substring(0, mText.length()-1);}mTextDetail[mDetailPos++]=mText;String temp = new String();temp = "";temp+=c;mTextDetail[mDetailPos++]=temp;mText="";}else if(mTextDetail[mDetailPos-1].equals("(")==true){}else if(mTextDetail[mDetailPos-1].equals(")")==true){String temp = new String();temp = "";temp+=c;mTextDetail[mDetailPos++]=temp;}else if(mTextDetail[mDetailPos-1].equals(")")==false){String temp = new String();temp ="";temp+=c;mTextDetail[mDetailPos-1]=temp;}if(c=='+'||c=='-')if(mLeftBracketNum==0){Calculate();}}else if(c=='C'){mLeftBracketNum=0;mText="";for(int i=0;i<mDetailPos;i++){mTextDetail[i]="";}mDetailPos=0;mAns="0";}else if(c=='<'){if(mText!=""){if(mText.length()==1) mText="";else mText=mText.substring(0, mText.length()-1);}}else if(c=='='){if(mText!="")mTextDetail[mDetailPos++]=mText;for(int i=mLeftBracketNum;i>0;i--)//补全括号{mTextDetail[mDetailPos++]=")";}mTextDetail[mDetailPos++]="=";Calculate();for(int i=0;i<mDetailPos;i++){mTextDetail[i]="";}mDetailPos=0;mText="";}else if(c=='.'){if(mText!=""){if(mText.contains(".")==false){mText+=c;}}}else if(c=='('){if(mDetailPos==0){mTextDetail[mDetailPos++]="(";mLeftBracketNum++;}else if(mTextDetail[mDetailPos-1].equals("+")==true||mTextDetail[mDetailPos-1].equals("-")==true||mTextDetail[mDetailPos-1].equals("×")==true||mTextDetail[mDetailPos-1].equals("÷")==true){mTextDetail[mDetailPos++]="(";mLeftBracketNum++;}}else if(c==')'){if(mLeftBracketNum>0){if(mText!=""){mTextDetail[mDetailPos++]=mText;mTextDetail[mDetailPos++]=")";mLeftBracketNum--;mText="";}}}}/** * 中缀转后缀 */public void toSuffix(){for(int i=0;i<mDetailPos-1;i++)//-1是因为式子包含了最后的 = + - {if(mTextDetail[i].equals("+")==true||   mTextDetail[i].equals("-")==true){while(  mTemp.empty()==false&&   (mTemp.peek().equals("+")==true||   mTemp.peek().equals("-")==true||   mTemp.peek().equals("×")==true||   mTemp.peek().equals("÷")==true) ){mSuffix[mSuffixPos++]=(String) mTemp.peek();mTemp.pop();}mTemp.push(mTextDetail[i]);}else if(mTextDetail[i].equals("×")==true||mTextDetail[i].equals("÷")==true){while(  mTemp.empty()==false&&   (mTemp.peek().equals("×")==true||mTemp.peek().equals("÷")==true)){mSuffix[mSuffixPos++]=(String) mTemp.peek();mTemp.pop();}mTemp.push(mTextDetail[i]);}else if(mTextDetail[i].equals("(")==true){mTemp.push(mTextDetail[i]);}else if(mTextDetail[i].equals(")")==true){while(mTemp.peek().equals("(")==false){mSuffix[mSuffixPos++]=(String) mTemp.peek();mTemp.pop();}mTemp.pop();}else {mSuffix[mSuffixPos++]=mTextDetail[i];}}while(mTemp.empty()==false){mSuffix[mSuffixPos++]=(String) mTemp.peek();mTemp.pop();}}public void Calculate(){mSuffixPos=0;for(int i=0;i<100;i++){mSuffix[i]="";}while(mTemp.empty()==false){mTemp.pop();}toSuffix();//输出测试for(int i=0;i<mDetailPos;i++)System.out.print(mTextDetail[i]+" ");System.out.print("\n");for(int i=0;i<mSuffixPos;i++){System.out.print(mSuffix[i]+" ");}System.out.print("\n");for(int i=0;i<mSuffixPos;i++){if(mSuffix[i].equals("+")||mSuffix[i].equals("-") ||mSuffix[i].equals("×")||mSuffix[i].equals("÷")){double b = Double.valueOf((String) mTemp.pop()).doubleValue();double a = Double.valueOf((String) mTemp.pop()).doubleValue();double c = 0;if(mSuffix[i].equals("+")){c = a + b;}if(mSuffix[i].equals("-")){c = a - b;}if(mSuffix[i].equals("×")){c = a * b;}if(mSuffix[i].equals("÷")){c = a / b;}String str = Double.toString(c);mTemp.push(str);}else {mTemp.push(mSuffix[i]);}}mAns = (String) mTemp.pop();if(mAns.length()>16)//防止超出屏幕   如果超过了 改成指数形式输出更好mAns = mAns.substring(0, 16);}}