【算法与数据结构】中缀表达式转为后缀表达式

1.题目介绍

2.代码实现部分

import java.util.Stack;

public class Main {

private String testString = null;
private Stack<Character> stack = null;

public Main(String testString) {
this.testString = testString;
this.stack = new Stack<Character>();
}

private void analysisString() {
for (int i = 0; i < testString.length(); i++) {
char c = testString.charAt(i);
if (c == '+' || c == '-') {
if (stack.isEmpty() || stack.peek() == '(') {
stack.push(c);
} else {
while (!stack.isEmpty()
&& (stack.peek() == '*' || stack.peek() == '/'
|| stack.peek() == '+' || stack.peek() == '-')) {
System.out.print(stack.pop());
}
stack.push(c);
}
} else if (c == '*' || c == '/') {
if (stack.isEmpty() || stack.peek() == '+'
|| stack.peek() == '-' || stack.peek() == '(') {
stack.push(c);
} else {
while (!stack.isEmpty()
&& (stack.peek() == '/' || stack.peek() == '*')) {
System.out.print(stack.pop());
}
stack.push(c);
}
} else if (c == '(') {
stack.push(c);
} else if (c == ')') {
char temp = ' ';
while ((temp = stack.pop()) != '(') {
System.out.print(temp);
}
} else {
System.out.print(c);
}
}
if (!stack.isEmpty()) {
while (!stack.isEmpty()) {
System.out.print(stack.pop());
}
}
}

public static void main(String[] args) {
Main testStacknew = new Main("(a-b)*c+d");
testStacknew.analysisString();
}

}