表达式计算 逆波兰式 栈 可括号小数负数

/* * To change this license header, choose License Headers in Project Properties. * To change this template file, choose Tools | Templates * and open the template in the editor. */ import java.util.Stack; /** * 表达式计算，允许括号负数小数,不可省略运算符 * @author HQ-Alien */ public class CalculatedNotation { //中序表达式 private String notation; //中间利用的栈 private Stack oprateSck; //最终运算字符串组 private String[] reversePolish; /** * 默认无参构造 */ public CalculatedNotation(){ this.oprateSck = new Stack(); reversePolish = new String[100]; } /** * 含参构造 * @param notation */ public CalculatedNotation(String notation){ this.oprateSck = new Stack(); this.notation = notation; this.notation += "@"; reversePolish = new String[100]; } /** * 通过逆波兰式计算值 * @return */ public double calculate(){ for(int i = 0; i<reversePolish.length;i++){ if(reversePolish[i] == null) break; double x = 0; if(isOprate(reversePolish[i])){ switch (reversePolish[i]){ //source6中不支持switch中使用字符串，可以转为char后再用 case "+": x = (Double) oprateSck.pop() + (Double) oprateSck.pop() ; break; case "-": x = (Double) oprateSck.pop() ; x = (Double) oprateSck.pop() - x; break; case "*": x = (Double) oprateSck.pop() * (Double) oprateSck.pop() ; break; case "/": x = (Double) oprateSck.pop() ; x = (Double) oprateSck.pop() / x; break; case "^": x = (Double) oprateSck.pop() ; x = Math.pow((Double) oprateSck.pop() , x); break; } }else{ x = Double.valueOf(reversePolish[i]); } oprateSck.push(x); } double result = (Double) oprateSck.pop(); return result; } /** * 转化为逆波兰式 */ public void transToReversePolish(){ char[] infix = notation.toCharArray(); oprateSck.push('@'); int i=0; int j=0; while(i < infix.length){ while( infix[i] == ' ') i++; if( infix[i] == '@') break; if( infix[i] == '(' ){ oprateSck.push(infix[i]); i++; }else if( infix[i] == ')' ){ while( (Character)oprateSck.peek() != '(') reversePolish[j++] = ""+ oprateSck.pop();//此处加个""是为了把char转为String oprateSck.pop(); i++; }else if(infix[i] == '+' || infix[i] == '-' || infix[i] == '*' || infix[i] == '/' || infix[i] == '^'){ if( infix[i] == '-' ){ if(i==0 || infix[i-1] == '(') reversePolish[j++] = "0"; } char op = (Character)oprateSck.peek(); while(getPriority(op) >= getPriority(infix[i])){ reversePolish[j++] = "" + oprateSck.pop();//此处加个""是为了把char转为String op = (Character)oprateSck.peek(); } oprateSck.push(infix[i]); i++; }else{ if( (infix[i] < '0' || infix[i] > '9') && infix[i] != '.'){ System.out.println("你的表达式错了，错了！！！"); System.exit(1); } String temp = ""; while((infix[i] >= '0' && infix[i] <= '9') || infix[i] == '.'){ temp += infix[i]; i++; } reversePolish[j++] = temp; } } char ch =(Character)oprateSck.pop(); while(ch != '@'){ if(ch == '(') System.out.println("你的表达式绝对有问题的"); else{ reversePolish[j++] = "" + ch; ch =(Character)oprateSck.pop(); } } oprateSck.clear(); } /** * 获得运算符优先级 * @param op * @return */ public int getPriority(char op){ switch(op){ case '+': case '-': return 1; case '*': case '/': return 2; case '^': return 3; case '(': case '@': default : return 0; } } /** * 判断是否为操作符 * @param element * @return */ public boolean isOprate(String element){ return element.equals("+") || element.equals("-") || element.equals("*") || element.equals("/") || element.equals("^"); } /** * @return the notation */ public String getNotation() { return notation; } /** * @param notation the notation to set */ public void setNotation(String notation) { this.notation = notation; this.notation += "@"; } /** * @return the reversePolish */ public String getReversePolish() { String temp = ""; for(int i=0; i<reversePolish.length;i++){ if(reversePolish[i] == null) return temp; temp += reversePolish[i] +" "; } return temp; } }