java 写一个简单的计算器

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请点击好的，看完介绍，咱们就根据这个杭电oj上1237 这道题，改写一个用GUI写出来的小计算器，类似于这样：
然后通过输入显示结果，比如说：
可以看得出来，咱们得到的结果是正确的：
代码：
package Computer;import java.awt.BorderLayout;import java.awt.Color;import java.awt.Container;import java.awt.Font;import java.awt.GridLayout;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.util.Stack;import javax.swing.JApplet;import javax.swing.JButton;import javax.swing.JFrame;import javax.swing.JPanel;import javax.swing.JTextField;public class Count extends JApplet implements ActionListener{/** *  */private static final long serialVersionUID = 1L;private JTextField textField = new JTextField("请输入");String operator = "";//操作String input = "";//输入的 式子boolean flag =  true;//boolean flag1 = true;//boolean flag2 = true;public void init()//覆写Applet里边的init方法{Container C = getContentPane();JButton b[] = new JButton[16];JPanel panel = new JPanel();C.add(textField, BorderLayout.NORTH);C.add(panel,BorderLayout.CENTER);panel.setLayout(new GridLayout(4, 4,5,5));String name[]={"7","8","9","+","4","5","6","-","1","2","3","*","0","C","=","/"};//设置 按钮for(int i=0;i<16;i++)//添加按钮{b[i] = new JButton(name[i]);b[i].setBackground(new Color(192,192,192));b[i].setForeground(Color.BLUE);//数字键 设置为 蓝颜色if(i%4==3)b[i].setForeground(Color.RED);b[i].setFont(new Font("宋体",Font.PLAIN,16));//设置字体格式panel.add(b[i]);b[i].addActionListener(this);}b[13].setForeground(Color.RED);//非数字键，即运算键设置为红颜色b[13].setForeground(Color.RED);}public void actionPerformed(ActionEvent e) {int cnt = 0;String actionCommand = e.getActionCommand();if(actionCommand.equals("+")||actionCommand.equals("-")||actionCommand.equals("*") ||actionCommand.equals("/"))input +=" "+actionCommand+" ";//设置输入，把输入的样式改成 需要的样子else if(actionCommand.equals("C"))input = "";else if(actionCommand.equals("="))//当监听到等号时，则处理 input{input+= "="+compute(input);textField.setText(input);input="";cnt = 1;}elseinput += actionCommand;//数字为了避免多位数的输入 不需要加空格if(cnt==0)textField.setText(input);}private String compute(String input)//即1237 的 样例{String str[];str = input.split(" ");Stack<Double> s = new Stack<Double>();double m = Double.parseDouble(str[0]);s.push(m);for(int i=1;i<str.length;i++){if(i%2==1)              {                  if(str[i].compareTo("+")==0)                  {                      double help = Double.parseDouble(str[i+1]);                      s.push(help);                  }                                    if(str[i].compareTo("-")==0)                  {                      double help = Double.parseDouble(str[i+1]);                      s.push(-help);                  }                                    if(str[i].compareTo("*")==0)                  {                      double help = Double.parseDouble(str[i+1]);                      double ans = s.peek();//取出栈顶元素                      s.pop();//消栈                      ans*=help;                      s.push(ans);                  }                                    if(str[i].compareTo("/")==0)                  {                      double help = Double.parseDouble(str[i+1]);                      double ans = s.peek();                      s.pop();                      ans/=help;                      s.push(ans);                  }              }          }          double ans = 0d;          while(!s.isEmpty())          {              ans+=s.peek();              s.pop();          }          String result = String.valueOf(ans);        return result;}public static void main(String args[]){JFrame frame = new JFrame("Count");Count applet = new Count();frame.getContentPane().add(applet, BorderLayout.CENTER);applet.init();//applet的init方法applet.start();//线程开始frame.setSize(350, 400);//设置窗口大小frame.setVisible(true);//设置窗口可见}}
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