//stackpublic 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;  }}//InToPostpublic 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();      }    }  }}//Testpublic 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());  }}