Java 将中缀表达式转换成后缀表达式

使用堆栈进行表达式的堆栈将中缀（Infix）表达式转换成后缀（postfix）表达式

完整代码

import java.io.IOException;public class InToPost {private Stack theStack;private String input;private String output = "";public InToPost(String in) {input = in;int stackSize = input.length();theStack = new Stack(stackSize);}public String doTrans() {for (int j = 0; j < input.length(); j++) {char ch = input.charAt(j);switch (ch) {case '+': case '-':gotOper(ch, 1); break; case '*': case '/':gotOper(ch, 2); break; case '(': theStack.push(ch);break;case ')': gotParen(ch); break;default: output = output + ch; break;}}while (!theStack.isEmpty()) {output = output + theStack.pop();}System.out.println(output);return output; }public void gotOper(char opThis, int prec1) {while (!theStack.isEmpty()) {char opTop = theStack.pop();if (opTop == '(') {theStack.push(opTop);break;}else {int prec2;if (opTop == '+' || opTop == '-')prec2 = 1;elseprec2 = 2;if (prec2 < prec1) { theStack.push(opTop);break;}elseoutput = output + opTop;}}theStack.push(opThis);}public void gotParen(char ch){ while (!theStack.isEmpty()) {char chx = theStack.pop();if (chx == '(') break; elseoutput = output + chx; }}public static void main(String[] args) throws IOException {String input = "1+2*4/5-7+3/6";String output;InToPost theTrans = new InToPost(input);output = theTrans.doTrans(); System.out.println("Postfix is " + output + '\n');}class Stack {private int maxSize;private char[] stackArray;private int top;public Stack(int max) {maxSize = max;stackArray = new char[maxSize];top = -1;}public void push(char j) {stackArray[++top] = j;}public char pop() {return stackArray[top--];}public char peek() {return stackArray[top];}public boolean isEmpty() {return (top == -1);}}
}