What can cause the "cannot find symbol" error in Java?

The “cannot find symbol” error occurs mainly when we try to reference a variable that is not declared in the program which we are compiling, it means that the compiler doesn’t know the variable we are referring to.

Some possible causes for “Cannot find symbol” to occur are

• Using a variable that is not declared or outside the code.
• Using wrong cases (“tutorials” and “Tutorials" are different) or making spelling mistakes.
• The packaged class has not been referenced correctly using an import declaration.
• Using improper identifier values like letters, numbers, underscore and dollar sign. The hello-class is different from helloclass.

Example

public class CannotFindSymbolTest {
   public static void main(String[] args) {
      int n1 = 10;
      int n2 = 20;
      sum = n1 + n2;
      System.out.println(sum);
   }
}

Output

CannotFindSymbolTest.java:5: error: cannot find symbol
sum = n1 + n2;
^
symbol: variable sum
location: class CannotFindSymbolTest
CannotFindSymbolTest.java:7: error: cannot find symbol
System.out.println(sum);
^
symbol: variable sum
location: class CannotFindSymbolTest

In the above program, "Cannot find symbol" error will occur because “sum” is not declared. In order to solve the error, we need to define “int sum = n1+n2” before using the variable sum.