Create 二手书交易网

二手书交易网

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+import java.awt.BorderLayout;import java.awt.Color;import java.awt.GridLayout;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;
+import javax.swing.JButton;import javax.swing.JFrame;import javax.swing.JPanel;import javax.swing.JTextField;
+import com.sun.org.apache.xalan.internal.xsltc.runtime.Operators;
+
+public class Mycalulator extends JFrame implements ActionListener {
+    private final String[]KEYS={"7","8","9","+","4","5","6","-","1","2","3","*","0",".","="};
+    private final String[]Command={"delete一位","归0"};
+    private JButton[] keys=new JButton[KEYS.length];
+    private JButton[] coms=new JButton[Command.length];
+    private JTextField text=new JTextField("0");
+    private boolean Firstdigit=true;//是否第一次输入
+    private double result=0.0;//结果
+    private String operator = "=";//默认操作为"="
+    private boolean operateValidFlag = true;//操作是否合法
+    public Mycalulator() {
+        // TODO Auto-generated constructor stub        init();
+        this.setTitle("只能计算加减乘除的..额东西");
+        this.setLocationRelativeTo(null);
+        this.setVisible(true);
+        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+        //this.setSize(width, height)
+        this.pack();
+    }
+    private void init() {
+        // TODO Auto-generated method stub
+        text.setHorizontalAlignment(JTextField.RIGHT);//文本右对齐
+        text.setEditable(false);//不可编辑
+        text.setBackground(Color.WHITE);//背景白色
+        JPanel keyspanel=new JPanel();//装按键的画板
+        keyspanel.setLayout(new GridLayout(4,4,3,3));//布局为网格布局4行4列 水平竖直间距都为3像素
+        for(int i=0;i<keys.length;i++){//创建按钮
+            keys[i]=new JButton(KEYS[i]);
+            keyspanel.add(keys[i]);//在画板上添加按钮
+            keys[i].setForeground(Color.blue);//按键前景色蓝色        }
+        //运算符按键前景色为红
+        keys[3].setForeground(Color.red);
+        keys[7].setForeground(Color.red);
+        keys[11].setForeground(Color.red);
+        keys[14].setForeground(Color.red);
+        JPanel comspanel=new JPanel();
+        comspanel.setLayout(new GridLayout(1,2,3,3));
+        for(int i=0;i<coms.length;i++){
+            coms[i]=new JButton(Command[i]);
+            comspanel.add(coms[i]);
+        }
+        JPanel panel1=new JPanel();
+        panel1.setLayout(new BorderLayout(3,3));// 画板采用边界布局管理器，画板里组件之间的水平和垂直方向上间隔都为3象素
+        panel1.add("North", comspanel);
+        panel1.add("Center", keyspanel);
+        JPanel top = new JPanel();  //装文本框的画板
+        top.setLayout(new BorderLayout()); //边界布局
+        top.add("Center", text);  
+        getContentPane().setLayout(new BorderLayout(3,5));
+        getContentPane().add("North", top);  //北  放置top画板 里面是文本框
+        getContentPane().add("Center", panel1);  //中心  放置panel1画板 装的是数字按键和命令按键
+        for (int i = 0; i < KEYS.length; i++) {  
+            keys[i].addActionListener(this);  
+        }  
+        for (int i = 0; i < Command.length; i++) {  
+            coms[i].addActionListener(this);  
+        }  
+    }
+    @Override
+    public void actionPerformed(ActionEvent e) {
+        // TODO Auto-generated method stub
+        String label=e.getActionCommand();
+        if(label==Command[0]){
+            handledelete();
+        }
+        else if(label==Command[1]){
+            handleC();
+        }
+        else if("0123456789.".indexOf(label)>=0){
+            handlenumber(label);
+        }
+        else{
+            handleOperator(label);
+        }
+    }
+    private void handleOperator(String label) {
+        // TODO Auto-generated method stub
+        if(operator.equals("/")){
+            if(text.getText()=="0"){
+                text.setText("除数不能为0");
+                operateValidFlag=false;
+                handleC();
+            }
+            else{
+                result/=Double.valueOf(text.getText());
+            }
+        }
+        else if(operator.equals("*")){
+            result*=Double.valueOf(text.getText());
+        }
+        else if(operator.equals("+")){
+            result+=Double.valueOf(text.getText());
+        }
+        else if(operator.equals("-")){
+            result-=Double.valueOf(text.getText());
+        }
+        else if(operator.equals("=")){
+            result=Double.valueOf(text.getText());
+        }
+        if(operateValidFlag){
+            text.setText(String.valueOf(result));
+        }
+        operator=label;
+        Firstdigit = true;//按完运算符后 在输入数字为第一次输入
+        operateValidFlag=true;
+    }
+    private void handlenumber(String label) {
+        // TODO Auto-generated method stub
+        if(Firstdigit){
+            if(label.equals(".")){
+                text.setText(text.getText()+".");
+            }
+            else{
+            text.setText(label);
+            }
+        }
+        //按的是"."并且字符串里没"."
+        else if(label.equals(".")&&text.getText().indexOf(".")<0){
+            text.setText(text.getText()+".");
+        }
+        //按得是数字
+        else if(!label.equals(".")){
+            text.setText(text.getText()+label);
+        }
+        Firstdigit=false;//输过就不是第一次输入了    }
+    private void handleC() {
+        // TODO Auto-generated method stub
+        text.setText("0");
+        Firstdigit=true;
+        operator="=";
+    }
+    private void handledelete() {
+        // TODO Auto-generated method stub
+        if(text.getText().length()>1){
+            text.setText(text.getText().substring(0, text.getText().length()-1));
+        }
+        else if(text.getText().length()==1){
+            text.setText("0");
+        }
+    }
+    public static void main(String args[]) {  
+        Mycalulator calculator1 = new Mycalulator();  
+         //        Mycalulator.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);      }  
+}
+
+