UndeclaredVariables
DRAFT
Observed

UndeclaredVariables
Incorrect

Variables can be used even without being declared beforehand

Correct

Variables must be declared before they are used

Correction
Here is what's right.

All variables have to be declared before being used. The place of the declaration determines whether a variable is a local variable, a method argument, an instance variable, or a class variable. The declaration also specifies the type of the variable.