Q-1:
===

class Employee extends Employer{
	public Employee(){
		super();
	}
}

===============================


class Student{
	public Student(){
		super();
	}
}

==> For any class "Object class" act as Parent Class.
==> from the above scenario, the super() can invoke Object class's default constructor.
==================================================================
/*
 * WAP in Java to create the ArrayList to store Employee Object.
 * And Display the information of Female Employees only.
 * And also display the employee information who are having above 5 years of experience.
 */

package pack1;

import java.util.ArrayList;
import java.util.Iterator;

class Employee{
	private int empNo;
	private String ename;
	private double salary;
	private String gender;
	private double experience;
	
	// creating the constructor for initializing class data members
	
	public Employee(int empNo, String ename, double salary, String gender, double experience) {
		super();
		this.empNo = empNo;
		this.ename = ename;
		this.salary = salary;
		this.gender = gender;
		this.experience = experience;
	}
	
	// defining setters and getters

	public int getEmpNo() {
		return empNo;
	}

	public void setEmpNo(int empNo) {
		this.empNo = empNo;
	}

	public String getEname() {
		return ename;
	}

	public void setEname(String ename) {
		this.ename = ename;
	}

	public double getSalary() {
		return salary;
	}

	public void setSalary(double salary) {
		this.salary = salary;
	}

	public String getGender() {
		return gender;
	}

	public void setGender(String gender) {
		this.gender = gender;
	}

	public double getExperience() {
		return experience;
	}

	public void setExperience(double experience) {
		this.experience = experience;
	}
	
	// generate toString()

	@Override
	public String toString() {
		return "Employee [empNo=" + empNo + ", ename=" + ename + ", salary=" + salary + ", gender=" + gender
				+ ", experience=" + experience + "]";
	}
	
	
	
}

public class MainClass {
	
	private static  ArrayList<Employee> getEmployeeList(){
		ArrayList<Employee> empList = new ArrayList<>();
		empList.add(new Employee(7928,"Amisha",55000.0,"Female",3.5));
		empList.add(new Employee(7929,"Ashok",45000.0,"Male",3.2));
		empList.add(new Employee(7930,"Akshay",25000.0,"Male",1.5));
		empList.add(new Employee(7931,"Bhavana",76000.0,"Female",5.5));
		empList.add(new Employee(7932,"Keerthi",45000.0,"Female",3.0));
		empList.add(new Employee(7933,"Vijay Gopal",105000.0,"Male",6.5));
		empList.add(new Employee(7934,"Vijay",35000.0,"Male",1.5));
		empList.add(new Employee(7935,"Vinitha",45000.0,"Female",3.0));
		empList.add(new Employee(7936,"Vignesh",125000.0,"Male",6.7));
		empList.add(new Employee(7937,"Ananya",119000.0,"Female",7.1));
		
		return empList;
	}

	public static void main(String[] args) {
		ArrayList<Employee> empList = getEmployeeList(); // method is calling
		
		Iterator<Employee> it = empList.iterator();  // creating an iterator object
		
		System.out.println("Getting of Female Employee DEtails..");
		
		while(it.hasNext()) {
			Employee emp = it.next();
			if(emp.getGender().equalsIgnoreCase("Female")) {
				System.out.println(emp);
			}
		}
		
		System.out.println("===================================================");
		
		System.out.println("Getting 5+ Years of Experience People details...");
		Iterator<Employee> ir = empList.iterator();
		while(ir.hasNext()) {
			Employee emp = ir.next(); 
			if(emp.getExperience() >= 5) {
				System.out.println(emp);
			}
		}
	}
}
======================================================
Q: is it possible to invoke the static method in another static method without the reference of class name?
Ans: Yes,
when both static methods are from same class.

class A{
	static void m1(){
		....
		m2();
	}
	static void m2(){
		.....
		m1();
	}
}

===============================
Here:
m1() and m2() are from two different classes.
to call m1() in m2() we must use the className as reference.

class ClassA{
	static void m1(){
	}
}

class ClassB{
	static void m2(){
		ClassA.m1();
	}
}

======================================================================
Q: Can we store arraylist object into list variable?
Ans:Yes

class A{
	public static ArrayList<Employee> getEmployeeList(){
		// logic
		return ArrayListObject;
	}
}

class MainClass{
	public static void main(String[] args)
	{
		List<Employee> listEmp = getEmployeeList();
	}
}

=============================================
interface Vehicle{
}

class Car implements Vehicle{
}

class MainClass{
	public static void main(String[] args)
	{
		Vehicle v = new Vehicle(); // error, because object creation not possible for interface
		Vehicle v = new Car();
	}
}
=========================================================
interface Vehicle{
	start();
}

class Car implements Vehicle{
	start(){
	}
	stop(){
	}
}

class MainClass{
	public static void main(String[] args)
	{
		// Vehicle v = new Vehicle(); // error, because object creation not possible for interface
		Vehicle v = new Car();

		v.start(); // correct
		v.stop(); // error

		Car c = new Car();
		c.start();// correct
		c.stop(); // correct
	}
}