java - Testing for Balanced Delimiters using a Stack -

i made generic stack class based on singly linked list , trying use check user input balanced delimiters. checking these delimiters: (){}[]

stack code

public class slstack<t> {  //initializes first node private slstacknode<t> head; //initializes first node  //constructor initializes first node null simulate empty stack public slstack(){     head = null; }  //inner node class public static class slstacknode<t>{     public t data;     public slstacknode<t> next; }  //adds element top of stack public void push(t value){     slstacknode<t> newnode = new slstacknode<>();     newnode.data = value;     newnode.next = head;     head = newnode; }  //removes element top of stack public t pop(){     if (head == null){         throw new illegalstateexception("the list empty.");     }     t value = head.data;     head = head.next;     return value; }  //checks element @ top of stack public t top(){     if (head == null){         throw new illegalstateexception("the list empty.");     }     t value = head.data;     return value; }  public boolean isempty(){     return head ==  null; }   public void printstack(slstacknode<t> node, int depth) {     if (node.next != null) {         system.out.println(depth + " : " + node.data); //recurses through stack         //printstack(node.next);     }     system.out.println(depth + " : " + node.data); //recursive base case } } 

balance tester code

public class balanced { public static void main(string[] args) {     slstack<expressionscanner.token> delimstack = new slstack<>();     system.out.println("enter 1 expression per line.");     system.out.println("end program period on line itself.");     expressionscanner escan = new expressionscanner(new scanner(system.in));     while (escan.hasnext()) {         expressionscanner.token token = escan.next();          if (token.gettype() == expressionscanner.token.type.op || token.gettype() == expressionscanner.token.type.var){             //ignore these tokens             continue;         }          if (token.gettype() == expressionscanner.token.type.delim_open){             //push opening delimiter stack             delimstack.push(token);         }          if (token.gettype() == expressionscanner.token.type.delim_close){             //look matching opening delimiter in stack , pop stack             if (token == delimstack.top()){                 delimstack.pop();             }else{                 throw new illegalstateexception("imbalanced delimiter detected.");             }         }          if (delimstack.isempty()){             system.out.println("delimiters balanced.");         }else{             system.out.println("imbalanced delimiter detected.");         }          //system.out.println(token);     } } } 

when run tester says delimiter imbalanced no matter is. doing single opening delimiter causes there imbalance doesn't throw exception. throws exception on single closing delimiter or if there more 1 closing delimiters. if have 2 opening delimiters doesn't terminate either.

i can post code expressionscanner if needs it.

            if (token == delimstack.top()){             delimstack.pop();         }else{             throw new illegalstateexception("imbalanced delimiter detected.");         } 

if assumed correctly code throwing , exception here because it's expecting token of type delim_close receiving delim_open (provided input '()').

what should check whether delimstack.pop() = token.type.delim_open.