Find the output of Java programs | final Keyword | Set 1: Enhance the knowledge of Java final Keyword concepts by solving and finding the output of some Java programs.
Question 1:
public class Main {
final static int X = 10;
public static void main(String[] args) {
int Z;
int Y;
X = 20;
Y = 30;
Z = X + Y;
System.out.println(Z);
}
}
Question 2:
public class FinalEx {
final int X;
FinalEx() {
X = 10;
}
public static void main(String[] args) {
int Z = 0;
int Y = 20;
FinalEx F = new FinalEx();
Z = F.X + Y;
System.out.println(Z);
}
}
Question 3:
public class FinalEx {
final static int X;
public static void main(String[] args) {
int Z;
int Y = 20;
Z = X + Y;
System.out.println(Z);
}
}
Question 4:
public class FinalEx {
final int X;
final FinalEx() {
X = 10;
}
public static void main(String[] args) {
int Z;
int Y = 20;
FinalEx F = new FinalEx();
Z = F.X + Y;
System.out.println(Z);
}
}
Question 5:
final class Sample {
static void sayHello() {
System.out.println("Hello World");
}
}
public class Main: Sample {
public static void main(String[] args) {
sayHello();
}
}
Java programming
Answer Question 1:
Output:
Main.java:8: error: cannot assign a value to final variable X X = 20; ^ 1 errorExplanation:
The above program will generate syntax error because here we created a variable X initialized with 10. And we changed the value of X in the main() function but we cannot change the value of the final variable because the final keyword is used to create constants in Java.
Answer Question 2:
Output:
Explanation:
In the above program, we created a class FinalEx that contains a data member X using the final, and we initialized X with 10 in the constructor.
Now look to the main() method, here we created two local variables Y and Z initialized with 0 and 20 respectively, and we created the object of FinalEx class.
Now look to the below expression,
Z = F.X + Y; Z = 10 + 20; Z = 30;And then finally we print the value of Z on the console screen.
Answer Question 3:
Output:
/FinalEx.java:2: error: variable X not initialized in the default constructor final static int X; ^ 1 errorExplanation:
The above program will generate syntax error because we cannot create an uninitialized final variable in Java.
Answer Question 4:
Output:
/FinalEx.java:4: error: modifier final not allowed here final FinalEx() { ^ 1 errorExplanation:
The above program will generate syntax error because we cannot use the final keyword with the constructor of the class.
Answer Question 5:
Output:
FinalEx.java:7: error: '{' expected public class Main: Sample { ^ 1 errorExplanation:
The above program will generate syntax error because here we use a colon ":" operator to inherit Sample class into Main. We need to use the extends keyword for inheritance in Java.
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