Inheritance

1)

class A
{
 int i;
}
class B extends A
{
 int j;
 public static void main(String[] args) 
 {
  B obj1=new B();
  System.out.println(obj1.i);
  System.out.println(obj1.j);
 }
}

OP:
/*
0
0
*/
---------------------------------------------------------------------------
2)

//inside class D there are 3 members
class C
{
 int i;
 void test()
 {
        System.out.println("Test");
 }
}
class D extends C
{
 int j;
}
class E
{
 public static void main(String[] args) 
 {
  D d1=new D();
  d1.i=10;
  d1.j=20;
  d1.test();
  System.out.println(d1.i);
  System.out.println(d1.j);
 }
}

OP:
/*
Test
10
20
*/

---------------------------------------------------------------------------
3)

class F
{
 int i;
 static int j;
 void test1()
 {
        System.out.println("Test1");
 }
 static void test2()
 {
  System.out.println("Test2");
 }
}
class G extends F
{
 int k;
 static void test3()
 {
  System.out.println("Test3");
 }
 public static void main(String[] args) 
 {
  F.j=10;
  F.test2();
  G.test2();
  G.test3();
  System.out.println(G.j);
  F f1=new F();
  f1.i=20;
  f1.test1();
  G g1=new G();
  g1.i=30;
  g1.k=50;
  g1.test1();
    }
}

OP:
/*
Test2
Test2
Test3
10
Test1
Test1
*/
---------------------------------------------------------------------------
4)

class H
{
 int x;
}
class I extends H
{
 int y;
}
class J extends I
{ 
 int z;
}
class Manager
{
 public static void main(String[] args) 
 {
  H h1=new H();
  I i1=new I();
  J j1=new J();
  System.out.println(h1.x);
  System.out.println(i1.x);
  System.out.println(j1.x);
  System.out.println(i1.y);
  System.out.println(j1.y);
  System.out.println(j1.z);
    }
}
//while creating the object of J all class H,I and J will load in memory

OP:
all 0
---------------------------------------------------------------------------
5)

class K
{
 K()
 {
  //super();  //compiler keep super internally 
  System.out.println("K()");
 }
}
class L extends K
{
 L()
 {
  //super();  //compiler keep super internally 
  System.out.println("L()");
 }
}
class Manager
{
 public static void main(String[] args)
 {
  K k1=new K();
  System.out.println("------");
  L l1=new L();
  System.out.println("------");
 }
}
//constructor and initialization block (SIB,IIB) are not inherit to sub class
//every constructor should have the first statement either super() or this() calling statement
//if we are not keeping the super() or this() as a first statement in constructor ,compiler will keep super().
//even a parent class have super() statement to Object class.

OP:
/*
K()
------
K()
L()
------
*/
---------------------------------------------------------------------------
6)

class M extends Object
{
 M()
 {
  super();
  System.out.println("M()");
 }
}
class N extends M
{
 N()
 {
  super();
  System.out.println("N()");
 }
}
class O extends N
{
 O()
 {
  super();
  System.out.println("O()");
 }
}
class Manager2
{
 public static void main(String[] args) 
 {
  M m1=new M();
  System.out.println("------");
  N l1=new N();
  System.out.println("------");
  O o1=new O();
  System.out.println("------");
 }
}
//total 4 constructor are executing in this program

OP:
/*
M()
------
M()
N()
------
M()
N()
O()
------
*/
---------------------------------------------------------------------------
7)

class P 
{
 P()
 {
   System.out.println("P()");
 }
}
class Q extends P
{
 Q()
 {
   System.out.println("Q()");
 }
}
class R extends Q
{
 R()
 {
   System.out.println("R()");
 }
}
class S extends R
{
 S()
 {
   System.out.println("S()");
 }
}
class T extends S
{
 T()
 {
   System.out.println("T()");
 }
 public static void main(String[] args) 
 {
  P m1=new P();
  System.out.println("------");
  Q l1=new Q();
  System.out.println("------");
  R o1=new R();
  System.out.println("------");
  S s1=new S();
  System.out.println("------");
  T t1=new T();
  System.out.println("------");
 }
}

---------------------------------------------------------------------------
8)

class A 
{
 A()
 {
   System.out.println("A()");
 }
 A(int i)
 {
   System.out.println("A(int)");
 }
}
class B extends A
{
 B()
 {
   System.out.println("B()");
 }
 B(int i)
 {
   System.out.println("B(int)");
 }
}
class Manager
{
 public static void main(String[] args) 
 {
  A m1=new A();
  System.out.println("------");
  A l1=new A(20);
  System.out.println("------");
  B o1=new B();
  System.out.println("------");
  B s1=new B(30);
  System.out.println("------");
 }
}

OP:
/*
A()
------
A(int)
------
A()
B()
------
A()
B(int)
------
*/
---------------------------------------------------------------------------
9)

class E 
{
 E()
 {
   System.out.println("E()");
 }
}
class F extends E
{
 F(int i)
 {
   System.out.println("F(int)");
 }
}
class Manager2
{
 public static void main(String[] args) 
 {
  E m1=new E();
  System.out.println("------");
  F l1=new F(20);
 }
}

OP:
/*
E()
------
E()
F(int)
*/
---------------------------------------------------------------------------
10)

class G 
{
 G(int i)
 {
  System.out.println("G(int)");
 }
}
class H extends G
{
 H()
 {
  //super(10); if remove this super(10) will give compiler error
  System.out.println("H()");
 }
}
class Manager3
{
 public static void main(String[] args) 
 {
  G g1=new G(90);
  System.out.println("------");
  H h1=new H();
 }
}

OP:
/*H.java:11: cannot find symbol
symbol : constructor G()
location: class G
{
^
1 error
------------------
G(int)
------
G(int)
H()
*/
---------------------------------------------------------------------------
11)

class I
{
 I(double j)
 {
  System.out.println("I(double)");
 }
}
class J extends I
{
 J()
 {
  super(9.9);
  System.out.println("J()");
 }
 J(double d){
  super(d);
  System.out.println("J(double)");
 }
}
class Manager4
{
 public static void main(String[] args) 
 {
  I i1=new I(9.9);
  System.out.println("----------");
  J j1=new J();
  System.out.println("----------");
  J j2=new J(3.4);
 }
}

OP:
/*
I(double)
----------
I(double)
J()
----------
I(double)
J(double)
*/
---------------------------------------------------------------------------
12)

class K
{
 K()
 {
  System.out.println("K()");
 }
 {
  System.out.println("K-IIB");
 }
}
class L extends K
{
 L()
 {
  System.out.println("L()");
 }
 {
  System.out.println("L-IIB");
 }
} 
class Manager5
{
 public static void main(String[] args) 
 {
  K k1=new K();
  System.out.println("----------");
  L l1=new L();
  System.out.println("----------");
 }
}

OP:
/*
K-IIB
K()
----------
K-IIB
K()
L-IIB
L()
----------
*/
---------------------------------------------------------------------------
13)

class M
{
 M()
 {
  System.out.println("M()");
 }
 {
  System.out.println("M-IIB-1");
 }
 {
  System.out.println("M-IIB-2");
 }
}
class N extends M
{
 N()
 {
  System.out.println("N()");
 }
 {
  System.out.println("N-IIB-1");
 }
 {
  System.out.println("N-IIB-2");
 }
} 
class Manager6
{
 public static void main(String[] args) 
 {
  M k1=new M();
  System.out.println("----------");
  N l1=new N();
  System.out.println("----------");
 }
}

OP:
/*
M-IIB-1
M-IIB-2
M()
----------
M-IIB-1
M-IIB-2
M()
N-IIB-1
N-IIB-2
N()
----------
*/
---------------------------------------------------------------------------
14)

class O 
{
  {
   System.out.println("O-IIB");
 }
 O()
 {
   System.out.println("O()");
 }
}
class P extends O
{
 P()
 {
   System.out.println("P()");
 }
 {
   System.out.println("P-IIB");
 }
 P(int i)
 {
  this();//IT will call constructor of same class
   System.out.println("P(int)");
 }
}
class Manager7
{
 public static void main(String[] args) 
 {
  O m1=new O();
  System.out.println("------");
  P o1=new P();
  System.out.println("------");
  P s1=new P(30);
  System.out.println("------");
 }
}

OP:
/*
O-IIB
O()
------
O-IIB
O()
P-IIB
P()
------
O-IIB
O()
P-IIB
P()
P(int)
------
*/