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Java Objects & Classes Quiz 9

The quiz below tests your knowledge of the material learnt in Objects & Classes - Lesson 9 - Final Instance Variables.

Question 1 : What will be output from this code snippet?

public class FinalInstanceVar {
    final int i;
    FinalInstanceVar() {
        System.out.println(this.i);
    }
}
- The code snippet will not compile as final instance variables must be initialized before use.
Question 2 : An instance variable that is marked as final cannot be changed once it has been assigned a value?
- An instance variable that is marked as final CANNOT be changed once it has been assigned a value, in fact this will cause a compiler error.
Question 3 : What will be output from this code snippet?

public class FinalInstanceVar {
    final int i = 678;
    FinalInstanceVar() {
        System.out.println(this.i);
    }
    public static void main (String[] args) {
        FinalInstanceVar fiv = new FinalInstanceVar();
    }
}
- Code snippet will output 678.
Question 4 : An instance variable that is marked as final can be assigned a value from anywhere?
- An instance variable that is marked as final can only be assigned a value when defined or in its constructor.
Question 5 : What will be output from this code snippet?

public class FinalInstanceVar {
    final int i = 1;
    FinalInstanceVar() {
        this.i = 2);
        System.out.println(this.i);
    }
}
- When using the final access modifier once assigned a value can never be changed or you get a compiler error as in this case.
Question 6 : An instance variable that is marked as final must be assigned a value before first use?
- An instance variable that is marked as final MUST be assigned a value before first use or you get a compiler error.
Question 7 : What will be output from this code snippet?

public class FinalInstanceVar {
    final int i;
    FinalInstanceVar(int i) {
        this.i = i);
        System.out.println(this.i);
    }
    public static void main (String[] args) {
        FinalInstanceVar fiv = new FinalInstanceVar(1234);
    }
}
- The code snippet runs fine and outputs 1234.
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What's Next?

In the next quiz we test your knowledge of constructors basics and how we use them to instantiate objects of our classes.