表达式字符串转化为后缀表达式格式

Java数据结构和算法中文第二版.pdf 代码

StackX.javapackage com.ch4.infix;public class StackX {private int maxSize ;private char[] stackArray ;private int top ;public StackX(int size){maxSize = size ;stackArray = new char[size] ;top = -1 ;}public void push(char elem){stackArray[++top] = elem ;}public char pop(){return stackArray[top--] ;}public char peek(){return stackArray[top] ;}public boolean isEmpty(){return (top == -1) ;}public char peekIndex(int index){return stackArray[index] ;}public int size(){return top +1 ;}public void displayStack(String info){System.out.print(info) ;System.out.print("Stack (bottom -->top): ") ;for (int j = 0; j < size(); j++){System.out.print(peekIndex(j)) ;System.out.print(' ');}System.out.println() ;}}Infix.javapackage com.ch4.infix;public class Infix {private StackX theStack;private String input;private String output = "";public Infix() {}public Infix(String in) {input = in;int stackSize = input.length();theStack = new StackX(stackSize);}public String doTrans() {for (int i = 0; i < input.length(); i++) {char ch = input.charAt(i);if (ch == ' '){continue ;}theStack.displayStack("For " + ch + " ");switch (ch) {case '+':case '-':gotOper(ch, 1);break;case '*':case '/':gotOper(ch, 2);break;case '(':theStack.push(ch);break;case ')':gotParent(ch);break;default:output += ch;break;}}while (!theStack.isEmpty()) {theStack.displayStack("While ");output += theStack.pop();}theStack.displayStack("End  ");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 = 2;if (opTop == '+' || opTop == '-') {prec2 = 1;}if (prec2 < prec1) {theStack.push(opTop);break;} else {output += opTop;}} // end else} // end whiletheStack.push(opThis);}public void gotParent(char ch) {while (!theStack.isEmpty()) {char chx = theStack.pop();if (chx == '(') {break;} else {output += chx;}} // end while}}InfixApp.javapackage com.ch4.test;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import com.ch4.infix.Infix;public class InfixApp {/** * @param args * @throws IOException  */public static void main(String[] args) throws IOException {String input , output ;while(true ){System.out.print("Enter infix: ") ;System.out.flush() ;input = getString() ;if (input.equals("")){break ;}Infix theTrans = new Infix(input) ;output = theTrans.doTrans() ;System.out.println("src String : " + input) ;System.out.println("Postfix is :" + output) ; ;}}public static String getString() throws IOException{InputStreamReader isr = new InputStreamReader(System.in) ;BufferedReader br = new BufferedReader(isr) ;String s = br.readLine() ;return s ;}}