本文实例讲述了java数据结构与算法之中缀表达式转为后缀表达式的方法。分享给大家供大家参考，具体如下：
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//stack
public class StackX {
private int top;
private char[] stackArray;
private int maxSize;
//constructor
public StackX(int maxSize){
this.maxSize = maxSize;
this.top = -1;
stackArray = new char[this.maxSize];
}
//put item on top of stack
public void push(char push){
stackArray[++top] = push;
}
//take item from top of stack
public char pop(){
return stackArray[top--];
}
//peek the top item from stack
public char peek(){
return stackArray[top];
}
//peek the character at index n
public char peekN(int index){
return stackArray[index];
}
//true if stack is empty
public boolean isEmpty(){
return (top == -1);
}
//return stack size
public int size(){
return top+1;
}
}
//InToPost
public class InToPost {
private StackX myStack;
private String input;
private String outPut="";
//constructor
public InToPost(String input){
this.input = input;
myStack = new StackX(this.input.length());
}
//do translation to postFix
public String doTrans(){
for(int i=0; i<input.length(); i++){
char ch = input.charAt(i);
switch(ch){
case '+':
case '-':
this.getOper(ch,1);
break;
case '*':
case '/':
this.getOper(ch,2);
break;
case '(':
this.getOper(ch, 3);
break;
case ')':
this.getOper(ch, 4);
break;
default:
this.outPut = this.outPut + ch;
}
}
while(!this.myStack.isEmpty()){
this.outPut = this.outPut + this.myStack.pop();
}
return this.outPut;
}
//get operator from input
public void getOper(char ch, int prect1){
char temp;
if(this.myStack.isEmpty()||prect1==3){
this.myStack.push(ch);
}
else if(prect1==4){
while(!this.myStack.isEmpty()){
temp = this.myStack.pop();
if(temp=='(')continue;
this.outPut = this.outPut + temp;
}
}
else if(prect1==1){
temp = this.myStack.peek();
if(temp=='(') this.myStack.push(ch);
else{
this.outPut = this.outPut + this.myStack.pop();
this.myStack.push(ch);
}
}
else{
temp = this.myStack.peek();
if(temp=='('||temp=='+'||temp=='-') this.myStack.push(ch);
else{
this.outPut = this.outPut + this.myStack.pop();
}
}
}
}
//Test
public class TestInToPost {
private static InToPost inToPost;
private static String str;
public static void main(String []args){
str = "((A+B)*C)-D";
inToPost = new InToPost(str);
System.out.println(inToPost.doTrans());
}
}
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PS:算法实现不是很完善，有些复杂的表达式解析要出错，写出来做个纪念！
希望本文所述对大家java程序设计有所帮助。