java

pom.xml

@@ -0,0 +1,39 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>com.huangzp.Calculator</groupId>
+    <artifactId>Calculator</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>7</source>
+                    <target>7</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <dependencies>
+        <!-- https://mvnrepository.com/artifact/org.python/jython -->
+        <dependency>
+            <groupId>org.python</groupId>
+            <artifactId>jython</artifactId>
+            <version>2.7.0</version>
+        </dependency>
+        <dependency>
+            <groupId>org.jetbrains</groupId>
+            <artifactId>annotations-java5</artifactId>
+            <version>RELEASE</version>
+            <scope>compile</scope>
+        </dependency>
+    </dependencies>
+
+
+</project>

src/Main.java → src/main/java/Main.java

@@ -1,3 +1,5 @@
+import org.jetbrains.annotations.NotNull;
+
 import java.util.Stack;
 
 public class Main {
@@ -10,6 +12,7 @@ public static void main(String[] args) {
         System.out.println(ret);
     }
 
+    @org.jetbrains.annotations.NotNull
     public static String MakeFormula(){
         StringBuilder build = new StringBuilder();
         int count = (int) (Math.random() * 2) + 1; // generate random count
@@ -25,9 +28,10 @@ public static String MakeFormula(){
         return build.toString();
     }
 
+    @NotNull
     public static String Solve(String formula){
-        Stack<String> tempStack = new Stack<>();//Store number or operator
-        Stack<Character> operatorStack = new Stack<>();//Store operator
+        Stack<String> tempStack = new Stack<String>();  // Store number or operator
+        Stack<Character> operatorStack = new Stack<Character>();  // Store operator
         int len = formula.length();
         int k = 0;
         for(int j = -1; j < len - 1; j++){
@@ -37,19 +41,23 @@ public static String Solve(String formula){
                     tempStack.push(formula.substring(k));
                 }
                 else {
-                    if(k < j){
+                    // v-zhihu
+                    if (k <= j) {
                         tempStack.push(formula.substring(k, j + 1));
                     }
-                    if(operatorStack.empty()){
-                        operatorStack.push(formulaChar); //if operatorStack is empty, store it
-                    }else{
-                        char stackChar = operatorStack.peek();
-                        if ((stackChar == '+' || stackChar == '-')
-                                && (formulaChar == '*' || formulaChar == '/')){
-                            operatorStack.push(formulaChar);
-                        }else {
-                            tempStack.push(operatorStack.pop().toString());
-                            operatorStack.push(formulaChar);
+                    while (true) {
+                        if (operatorStack.empty()) {
+                            operatorStack.push(formulaChar); //if operatorStack is empty, store it
+                            break;
+                        } else {
+                            char stackChar = operatorStack.peek();
+                            if ((stackChar == '+' || stackChar == '-')
+                                    && (formulaChar == '*' || formulaChar == '/')) {
+                                operatorStack.push(formulaChar);
+                                break;
+                            } else {
+                                tempStack.push(operatorStack.pop().toString());
+                            }
                         }
                     }
                 }
@@ -59,7 +67,7 @@ public static String Solve(String formula){
         while (!operatorStack.empty()){ // Append remaining operators
             tempStack.push(operatorStack.pop().toString());
         }
-        Stack<String> calcStack = new Stack<>();
+        Stack<String> calcStack = new Stack<String>();
         for(String peekChar : tempStack){ // Reverse traversing of stack
             if(!peekChar.equals("+") && !peekChar.equals("-") && !peekChar.equals("/") && !peekChar.equals("*")) {
                 calcStack.push(peekChar); // Push number to stack