20162316_20162328结对编程第二周阶段总结

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();

}

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;

else

prec2 = 2;

if (prec2 < prec1) {

theStack.push(opTop);

break;

}

else

output = output + opTop;

}

}

theStack.push(opThis);

}

public void gotParen(char ch){

while (!theStack.isEmpty()) {

char chx = theStack.pop();

if (chx == '(')

break;

else

output = output + chx;

}

}

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);
}