Stack.peek() Error

[nani aman]

Hi all friendly ranch hand. I have an error which i couldn't figure out. It look simple but i still couldn't solve it by myself.

error 1
symbol : method peek ()
location: class Stack
top = stack.peek();

error 2
symbol : method equal (java.lang.String)
location: class java.lang.String
else if(!(top.equal(c1))) {stack.push(c1);}

this is my part of code:

if(bool == true){
count++;
top = stack.peek();
System.out.println("Number of occurences = "+ count);

if(stack.empty())  
                       {stack.push(c1);}
else if(!(top.equal(c1))) 
                        {stack.push(c1);}

System.out.println("This is match at place = "+ (a+1));
}

i have import java.lang.String and declare the stack.
So why this error occurs?

Thanks kind ranch hands.

[ changed \ to / -ds ]
[ October 23, 2004: Message edited by: Dirk Schreckmann ]

[David Harkness]

Both messages mean that the compiler cannot find a method with a matching name and signature (sequence and types of parameters).

symbol : method peek ()
location: class Stack
top = stack.peek();

Since that says "Stack" and not "java.util.Stack", I assume Stack is your own class. Check the method name and signature. That looks like a correct definition of a peek() method, but without Stack's definition I can only guess.

symbol : method equal (java.lang.String)
location: class java.lang.String
else if(!(top.equal(c1))) {stack.push(c1);}

This one is looking for a method named "equal" in class String that takes a String (or one of its superclass/interfaces, like Object). Look in the JavaDocs for String and you'll see that it overrides the method "boolean equals(Object)" from Object (note the "s").

Here's a free pointer:

if(bool == true){

This is equivalent to

if(bool){

[ October 22, 2004: Message edited by: David Harkness ]

[nani aman]

Actually i use Class Stack in java.util and i already using java.util.*. For stack.peek(), it receive String data type and i put at variable top to compare. I have see the JavaDoc but how to define wrong?

wish you can guide me. :roll:

[Jimmy Die]

Hi,


your method definition equal() correct?

Or you should equals() with an 's'.

[David Harkness]

Originally posted by nani aman:
Actually i use Class Stack in java.util and i already using java.util.*. For stack.peek(), it receive String data type and i put at variable top to compare. I have see the JavaDoc but how to define wrong?

Given that the error message says "class Stack" and not "class java.util.Stack" (note that the other error message says "java.lang.String"), I would guess you have a variable named "Stack" with a capital S or you have defined your own Stack class.

If you post your code we'll be able to help you.