结对学习四则运算

四则运算结队学习

代码：
-import java.util.*;
public class fourrule{

public char[] op = {'+','-','*','/','(',')'};  
public String[] strOp = {"+","-","*","/","(",")"};  
public boolean isDigit(char c){  
    if(c>='0'&&c<='9'){  
        return true;  
    }  
    return false;  
}  
public boolean isOp(char c){  
    for(int i=0;i<op.length;i++){  
        if(op[i]==c){  
            return true;  
        }  
    }  
    return false;  
}  
public boolean isOp(String s){  
    for(int i=0;i<strOp.length;i++){  
        if(strOp[i].equals(s)){  
            return true;  
        }  
    }  
    return false;  
}  
/** 
 * 处理输入的计算式 
 * @param str 
 * @return 
 */  
public List<String> work(String str){  
    List<String> list = new ArrayList<String>();  
    char c;  
    StringBuilder sb = new StringBuilder();  
    for(int i=0;i<str.length();i++){  
        c = str.charAt(i);  
        if(isDigit(c)){  
            sb.append(c);  
              
        }  
        if(isOp(c)){  
            if(sb.toString().length()>0){  
                list.add(sb.toString());  
                sb.delete(0, sb.toString().length());  
            }  
            list.add(c+"");  
        }  
    }  
    if(sb.toString().length()>0){  
        list.add(sb.toString());  
        sb.delete(0, sb.toString().length());  
    }  
    return list;  
}  
public void printList(List<String> list){  
    for(String o:list){  
        System.out.print(o+" ");  
    }  
}  
/** 
 * 中缀表达式转化为后缀表达式 
 * 1,遇到数字输出 
 * 2,遇到高优先级的全部出栈 
 * 3,最后全部出栈 
 */  
public List<String> InfixToPostfix(List<String> list){  
    List<String> Postfixlist = new ArrayList<String>();//存放后缀表达式  
    Stack<String> stack = new Stack<String>();//暂存操作符  
    //stack.push('#');  
    for(int i=0;i<list.size();i++){  
          
        String s = list.get(i);  
        if(s.equals("(")){  
            stack.push(s);  
        }else if(s.equals("*")||s.equals("/")){  
            stack.push(s);  
        }else if(s.equals("+")||s.equals("-")){  
            if(!stack.empty()){  
                while(!(stack.peek().equals("("))){  
                    Postfixlist.add(stack.pop());  
                    if(stack.empty()){  
                        break;  
                    }  
                }  
                stack.push(s);  
            }else{  
                stack.push(s);  
            }  
        }else if(s.equals(")")){  
            while(!(stack.peek().equals("("))){  
                Postfixlist.add(stack.pop());  
            }  
            stack.pop();  
        }else{  
            Postfixlist.add(s);  
        }  
        if(i==list.size()-1){  
            while(!stack.empty()){  
                Postfixlist.add(stack.pop());  
            }  
        }  
    }  
    return Postfixlist;  
}  
/** 
 * 后缀表达式计算 
 */  
public int doCal(List<String> list){  
    Stack<Integer> stack = new Stack<Integer>();  
    for(int i=0;i<list.size();i++){  
        String s = list.get(i);  
        int t=0;  
        if(!isOp(s)){  
            t = Integer.parseInt(s);  
            stack.push(t);  
        }else{  
            if(s.equals("+")){  
                int a1 = stack.pop();  
                int a2 = stack.pop();  
                int v = a2+a1;  
                stack.push(v);  
            }else if(s.equals("-")){  
                int a1 = stack.pop();  
                int a2 = stack.pop();  
                int v = a2-a1;  
                stack.push(v);  
            }else if(s.equals("*")){  
                int a1 = stack.pop();  
                int a2 = stack.pop();  
                int v = a2*a1;  
                stack.push(v);  
            }else if(s.equals("/")){  
                int a1 = stack.pop();  
                int a2 = stack.pop();  
                int v = a2/a1;  
                stack.push(v);  
            }  
        }  
    }  
    return stack.pop();  
}  

}
import java.util.*;

public class Test {

public static void main(String[] args) {  
    fourrule lt = new fourrule();  
    String str = "9+(3-1)*3+10/2";  
    List<String> list = lt.work(str);  
    List<String> list2 = lt.InfixToPostfix(list);  
    System.out.println("原式为："+str);  
    System.out.print("后缀表达式为：");  
    lt.printList(list2);  
    System.out.println(" ");  
    System.out.println("计算结果为："+lt.doCal(list2));  
}  

}

缺陷:

代码中无法用Scanner输入，面对不同的计算式需要在Test.java内部修改运算式，由于时间问题，我与我的结对学习伙伴目前只做到了这一步。

运行结果：

结对学习照片：

码云链接：

https://gitee.com/BESTI-IS-JAVA-2018/20165213zqh/tree/master/src