Pattern: Explicit variable initialization
Issue: -
Checks if any class or object member is explicitly initialized to default for its type value (null for object references, zero for numeric types and char and false for boolean.
Rationale: Each instance variable gets initialized twice, to the same value. Java initializes each instance variable to its default value (0 or null) before performing any initialization specified in the code. So in this case, x gets initialized to 0 twice, and bar gets initialized to null twice. So there is a minor inefficiency. This style of coding is a holdover from C/C++ style coding, and it shows that the developer isn't really confident that Java initializes instance variables to default values.
To configure the check:
<module name="ExplicitInitialization"/>To configure the check so that it only checks for objects that explicitly initialize to null:
<module name="ExplicitInitialization">
<property name="onlyObjectReferences" value="true"/>
</module>Example:
public class Test {
private int a = 0;
private int b = 1;
private int c = 2;
private boolean a = true;
private boolean b = false;
private boolean c = true;
private boolean d = false;
private boolean e = false;
private A a = new A();
private A b = null; // violation
private C c = null; // violation
private D d = new D();
int ar1[] = null; // violation
int ar2[] = new int[];
int ar3[];
private Bar<String> bar = null; // violation
private Bar<String>[] barArray = null; // violation
public static void main( String [] args ) {
}
}