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V6052. Calling an overridden method in parent-class constructor may lead to use of uninitialized data.
The analyzer has detected a parent-class constructor that uses a method overridden in the derived class. As a result, the overridden method can be used by uninitialized class fields.
This behavior occurs when you fail to follow the class initialization procedure stated in JLS [12.5].
Consider the following example:
public class Parent {
private String parentStr = "Black";
public Parent () {
printInfo();
}
public void printInfo () {
System.out.println("Parent::printInfo");
System.out.println("parentStr: " + parentStr);
System.out.println("-----------------");
}
....
}
public class Child extends Parent {
private int childInt;
private String childStr;
public Child() {
super();
this.childInt = 25;
this.childStr = "White";
}
public void printInfo () {
super.printInfo();
System.out.println("Child::printInfo");
System.out.println("childInt: "+childInt+";childStr: "+childStr);
System.out.println("-----------------");
}
....
}If we execute the following line:
Child obj = new Child();the program will print:
Parent::printInfo
parentStr: Black
-----------------
Child::printInfo
childInt: 0 ; childStr: null
-----------------As seen from this fragment, the overridden method 'printInfo' was called in the parent-class constructor of the 'Parent' class, while the derived 'Child' class was not fully initialized – hence the default values, rather than user-specified values, of the 'childInt' and 'childStr' fields.
The conclusion is this: make sure your parent-class constructors do not use methods that could be overridden in child classes. And if you do use a class method in a constructor, declare it final or private.
This diagnostic is classified as:
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You can look at examples of errors detected by the V6052 diagnostic. |
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