.idea/misc.xml

@@ -1,3 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="ProjectRootManager" version="2" languageLevel="JDK_1_8" default="true" project-jdk-name="1.8" project-jdk-type="JavaSDK">
     <output url="file://$PROJECT_DIR$/out" />

src/Computer.java

@@ -11,6 +11,7 @@ public class Computer extends JFrame{
     public static void main(String[] args) {
         Computer t = new Computer();
     }
+
     public Computer() {
         this.setTitle("计算器");
         Container c = getContentPane();
@@ -37,6 +38,7 @@ public class Computer extends JFrame{
         aJButtons[13]=new JButton("/");
         aJButtons[14]=new JButton("=");
         aJButtons[15]=new JButton(".");
+
         aj.add(aJButtons[7]);
         aj.add(aJButtons[8]);
         aj.add(aJButtons[9]);
@@ -56,6 +58,7 @@ public class Computer extends JFrame{
         c.add(aj, BorderLayout.CENTER);
         setSize(400, 400);
         setVisible(true);
+
         for(int i = 0; i < 10; i++) {
             final String o = aJButtons[i].getActionCommand();
             aJButtons[i].addActionListener(new ActionListener() {
@@ -115,18 +118,22 @@ public class Computer extends JFrame{
                 }
 
                 else if(flag == 1) {
+//加法
                     b = Double.parseDouble(sz[0]) + Double.parseDouble(sz[1]);
                 }
 
                 else if(flag == 2) {
+//减法
                     b = Double.parseDouble(sz[0]) - Double.parseDouble(sz[1]);
                 }
 
                 else if(flag == 3) {
+//乘法
                     b = Double.parseDouble(sz[0]) * Double.parseDouble(sz[1]);
                 }
 
                 else if(flag == 4) {
+//除法
                     b = Double.parseDouble(sz[0]) / Double.parseDouble(sz[1]);
                 }