can we override private methods in java?

No, we cannot override the private methods because private methods will not be inherited to sub class.

Example

class SubtractionTest {
 
    private void subtraction(int num1, int num2) {
        System.out.println("Inside super class method");
        System.out.println(num1 - num2);
    }
 
 }
 
public class Main extends SubtractionTest
{
 
    public static void main(String[] args) {
		Main main = new Main();
		main.subtraction(150, 100);
	}
}

Example

Main.java:15: error: cannot find symbol
		main.subtraction(150, 100);
		    ^
  symbol:   method subtraction(int,int)
  location: variable main of type Main
1 error

Note: If we create the same method in subclass then JVM will consider it as a sub class method, not the overridden method.
Example

class SubtractionTest {
 
    private void subtraction(int num1, int num2) {
        System.out.println("Inside super class method");
        System.out.println(num1 - num2);
    }
 
 }
 
public class Main extends SubtractionTest
{
    void subtraction(int num1, int num2) {
        System.out.println("Inside sub class method");
        System.out.println(num1 - num2);
    }
    public static void main(String[] args) {
		Main main = new Main();
		main.subtraction(150, 100);
	}
}

Example

Inside sub class method                                
50

Java interview questions on method overloading and overriding