Calculation of infix simple arithmetic expression for Java stack implementation

 Public Abstract classStack<t> {     Public Abstract BooleanIsEmpty ();  Public Abstract BooleanIsfull ();  Public AbstractT Top ();  Public Abstract Booleanpush (T x);  Public AbstractT pop ();  Public Abstract voidclear ();}

 Public classSeqstack<t>extendsStack<t> {    Privateobject[] Elementdata; Private intMaxtop; Private inttop;  PublicSeqstack (intsize) {         This. Maxtop = size-1; Elementdata=NewObject[size]; Top=-1; } @Override Public BooleanIsEmpty () {returntop = =-1; } @Override Public BooleanIsfull () {returntop = = MaxTop-1; } @SuppressWarnings ("Unchecked") @Override PublicT Top () {if(top = =-1) {System.out.println ("Empty"); return NULL; }        return(T) elementdata[top]; } @Override Public Booleanpush (T x) {if(top = =maxtop) {System.err.println ("Full"); return false; } elementdata[++top] =x; return true; } @SuppressWarnings ("Unchecked") @Override PublicT Pop () {if(top = =-1) {System.err.println ("Empty"); return NULL; } T result=(T) elementdata[top]; Elementdata[top]=NULL;//GCtop--; returnresult; } @Override Public voidClear () {//Let GC do it work         for(inti = 0; i < top+1; i++) {Elementdata[i]=NULL; } Top=-1; }}

 Public classStackcalc {PrivateSeqstack<integer>Stack;  PublicStackcalc (intmaxSize) {Stack=NewSeqstack<integer>(maxSize); }    Private voidPushoperand (Integer number) {Stack.push (number); }    PrivateNumber Dooperate (CharOper) {Integer Right=Stack.pop (); Integer Left=Stack.pop (); Integer result=NULL; if(Left! =NULL&& Right! =NULL) {            Switch(oper) { Case+: Result= Left.intvalue () +Right.intvalue ();  Break;  Case‘-‘: Result= Left.intvalue ()-Right.intvalue ();  Break;  Case‘*‘: Result= Left.intvalue () *Right.intvalue ();  Break;  Case‘/‘:                if(Right.intvalue () = = 0) {System.err.println ("Divide by 0"); } result= Left.intvalue ()/Right.intvalue ();  Break; default:                 Break;        }} stack.push (Result); returnresult; }    Private intIcpCharc) {Switch(c) { Case‘#‘:            return0;  Case‘(‘:            return7;  Case‘*‘:            return4;  Case‘/‘:            return4;  Case+:            return2;  Case‘-‘:            return2;  Case‘)‘:            return1; default:            return-1; }    }    Private intIspintc) {Switch(c) { Case‘#‘:            return0;  Case‘(‘:            return1;  Case‘*‘:            return5;  Case‘/‘:            return5;  Case+:            return3;  Case‘-‘:            return3;  Case‘)‘:            return7; default:            return-1; }    }     Publicstring Transfer (string expression) {StringBuilder sb=NewStringBuilder (); Seqstack<Character> stack =NewSeqstack<character>(Expression.length ()); Stack.push (‘#‘);  for(inti = 0; I < expression.length (); i++) {Character C=Expression.charat (i); if(' 0 ' <= C && c <= ' 9 ' | |                    ' A ' <= C && c <= ' Z ' | | ' A ' <= c && c <= ' Z ') {//Digit characterSb.append (c); } Else{//operator                if(ICP (c) > ISP (Stack.top ())) {//into the stackStack.push (c); } Else{//out of the stack                    if(c = = ') ') {                        CharCH =Stack.pop ();  while(ch! = ' (') {sb.append (CH); CH=Stack.pop (); }                    } Else {                        CharCH =Stack.pop ();  while(ICP (c) <=ISP (CH))                            {sb.append (CH); CH=Stack.pop ();                        } stack.push (CH);                    Stack.push (c); }                }            }        } //End of for        CharCH =Stack.pop ();  while(ch! = ' # ') {sb.append (CH); CH=Stack.pop ();                } stack.clear (); returnsb.tostring (); }     PublicInteger Calc (String expression) {expression=transfer (expression);  for(inti = 0; I < expression.length (); i++) {            Charc =Expression.charat (i); Switch(c) { Case+:             Case‘-‘:             Case‘*‘:             Case‘/‘: Dooperate (c);  Break; default: Pushoperand (NewInteger (c + ""));  Break; }        }        returnStack.pop (); }    /**     * @paramargs*/     Public Static voidMain (string[] args) {Stackcalc calc=NewStackcalc (10); System.out.println (Calc.calc ("6/(4-2) +3*2")); }}

Calculation of infix simple arithmetic expression for Java stack implementation