can we declare overloaded methods as final?

Yes, we can declare overloaded methods as final.

class SumTest {
 
    public final void sum(int num1, int num2) {
        System.out.println(num1 + num2);
    }
 
    public void sum(int num1, int num2, int num3) {
        System.out.println(num1 + num2 + num3);
    }
 }
 
public class Main
{
	public static void main(String[] args) {
		SumTest sumTest = new SumTest();
		sumTest.sum(10, 5);
		sumTest.sum(10, 5, 20);
	}
}

Output

15
35

Note: Final method can not be overridden. See the below example.

class SumTest {
 
    public final void sum(int num1, int num2) {
        System.out.println(num1 + num2);
    }
 
    public final void sum(int num1, int num2, int num3) {
        System.out.println(num1 + num2 + num3);
    }
 }
 
public class Main extends SumTest
{
    public void sum(int num1, int num2) {
        System.out.println(num1 + num2);
    }
	public static void main(String[] args) {
		SumTest sumTest = new SumTest();
		sumTest.sum(10, 5);
		sumTest.sum(10, 5, 20);
		Main main = new Main();
		main.show();
	}
}

Output

Main.java:14: error: sum(int,int) in Main cannot override sum(int,int) in SumTest
    public void sum(int num1, int num2) {
                ^
  overridden method is final
Main.java:22: error: cannot find symbol
		main.show();
		    ^
  symbol:   method show()
  location: variable main of type Main
2 errors

Note: A non final method can not be overloaded as well as overridden with final declaration.

class SumTest {
 
    public void sum(int num1, int num2) {
        System.out.println(num1 + num2);
    }
 
    public final void sum(int num1, int num2, int num3) {
        System.out.println(num1 + num2 + num3);
    }
 }
 
public class Main extends SumTest
{
    public final void sum(int num1, int num2) {
        System.out.println(num1 + num2);
    }
	public static void main(String[] args) {
		SumTest sumTest = new SumTest();
		sumTest.sum(10, 5);
		sumTest.sum(10, 5, 20);
		Main main = new Main();
		main.sum(10, 5);
	}
}

Output

15
35
15

Java interview questions on method overloading and overriding

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