Object class in java - programs

Program No. 1

class A
{
    String name;
    int rollno;
    
    A(String name, int rollno)
    {
      this.name = name;
      this.rollno = rollno;
    } 
  
    public String toString()
    {
      return name + " " + rollno;
    }
}
class M1
{
    public static void main(String[] args) 
    {
      A a1 = new A("vijay", 101);
      A a2 = new A("adam", 102);
      System.out.println(a1);
      System.out.println(a2);
    }
} 

o/p: 

vijay 101
adam 102
		  

Program No. 2

import java.lang.reflect.*;
class M2
{
  public static void main(String[] args) throws Exception
  {
    int count = 0;
    Class c = Class.forName("java.lang.Object");
    Method[] m = c.getDeclaredMethods();
    for(Method m1 : m)
    {
      count++;
      System.out.println(m1.getName());
    }
    System.out.println("The number of methods:" + count);
  }
}

 output: 

finalize
wait
wait
wait
equals
toString
hashCode
getClass
clone
notify
notifyAll
The number of methods:11
          

Program No. 3

class E
{
  int i;

  public String toString()
  {
    return "" + this.i;
  }
}
class M3
{
  public static void main(String[] args)
  {
    E e1 = new E();
    e1.i = 10;
    E e2 = new E();
    e2.i = 20;
    System.out.println(e1);//address of the object instead of content
    System.out.println(e2);//hexadecimal repr of mem address
  }
}
 output: 
10
20
            

Program No. 4

class F
{
	int i;

	public String toString()
	{
		return "its a type object with i value as: " + i;
	}
}
class M4
{
	public static void main(String[] args) 
	{
		F f1 = new F();
		f1.i = 20;
		System.out.println(f1);
	}
}
 output: 
its a type object with i value as: 20
          

Program No. 5

class G
{
	int i;
	public String toString()
	{
		return "its a type object with i value as :" + i;
	}
}
class M5
{
	public static void main(String[] args) 
	{
		G g1 = new G();
		g1.i = 20;
		System.out.println(g1);
		String s1 = "description: " + g1;
		System.out.println(s1);
	}
}
 output: 
its a type object with i value as :20
description: its a type object with i value as :20
          

Program No. 6

class B
{
  int i, j;

  B(int k, int l)
  {
    this.i = k;
    this.j = l;
  }

  public String toString()
  {
    return i + ":" + j;
  }
}
class M6
{
  public static void main(String[] args) 
  {
    B b1 = new B(10, 20);
    System.out.println(b1);
  }
}
 output: 
10:20
        

Program No. 7

class C
{
	int i;

	public String toString()
	{
		return "i = " + i;
	}
}
class D
{
	int j;
	C c_ref;

	public String toString()
	{
		return "j = " + j + ", " + c_ref;
	}
}
class M7  
{
	public static void main(String[] args) 
	{
		C c1 = new C();
		c1.i = 10;
		D d1 = new D();
		d1.j = 20;
		d1.c_ref = c1;
		System.out.println(c1);
		System.out.println(d1);
	}
}
 output: 
i = 10
j = 20, i = 10
        

Program No. 8

import java.util.ArrayList;
class M8 
{
	public static void main(String[] args) 
	{
		String s1 = "Hello";
		Integer obj = 10;
		Thread t1 = new Thread();
		ArrayList list = new ArrayList();
		System.out.println(s1);
		System.out.println(obj);
		System.out.println(t1);
		System.out.println(list);
	}
}
 output: 
Hello
10
Thread[Thread-0,5,main]
[]
        

Program No. 9

 output: 
        

Program No. 6

 output: 
        

Program No. 6

 output: