00:00
/*01, no argument */
public class G01{
void show(){
System.out.println("1");
}
}
class Xyz extends G01{
void show(){
System.out.println("2");
}
public static void main(String[] args){
G01 t=new G01();
t.show();
Xyz x=new Xyz();
x.show();
}
}
// 1
// 2
/*02, same sequence of parameters */
public class G02{
void show(String a, int b){
System.out.println("sequence-1");
}
}
class Xyz extends G02{
void show(String a, int b){
System.out.println("sequence-2");
}
public static void main(String[] args){
G02 t=new G02();
t.show("raj",10);
Xyz x=new Xyz();
x.show("ram",20);
}
}
// sequence-1
// sequence-2
/*03, same parameters */
public class G03{
void show(int a, int b){
System.out.println("same number of arguments-1");
}
}
class Xyz extends G03{
void show(int a, int b){
System.out.println("same number of arguments-2");
}
public static void main(String[] args){
G03 t=new G03();
t.show(10,20);
Xyz x=new Xyz();
x.show(30,40);
}
}
// same number of arguments-1
// same number of arguments-2
/*04, single same type of argument */
public class G04{
void show(String a){
System.out.println("type of arguments-1");
}
}
class Xyz extends G04{
void show(String a){
System.out.println("type of arguments-2");
}
public static void main(String[] args){
G04 t=new G04();
t.show("monika");
Xyz x=new Xyz();
x.show("jyoti");
}
}
// type of arguments-1
// type of arguments-2
/*05, Return-Type (pt. = cld.), (OBJECT = STRING) */
public class G05{
Object show(String a){
System.out.println("covariant return type-1");
return null;
}
}
class Xyz extends G05{
String show(String a){
System.out.println("covariant return type-2");
return null;
}
public static void main(String[] args){
G05 t=new G05();
t.show("monika");
Xyz x=new Xyz();
x.show("jyoti");
}
}
// covariant return type-1
// covariant return type-2
/*06, Return-Type (cld.=pt.), (STRING=OBJECT) */
public class G06{
String show(String a){
System.out.println("covariant return type-1");
return null;
}
}
class Xyz extends G06{
Object show(String a){
System.out.println("covariant return type-2");
return null;
}
public static void main(String[] args){
G06 t=new G06();
t.show("monika");
Xyz x=new Xyz();
x.show("jyoti");
}
}
// show(String) in Xyz cannot override show(String) in G06 Object show(String a){
// return type Object is not compatible with String
/*07, pt. & cld. mt A.Mod. is default */
public class G07 {
void show(String a){
System.out.println("covariant return type-1");
}
}
class Xyz extends G07{
void show(String a){
System.out.println("covariant return type-2");
}
public static void main(String[] args){
G07 t=new G07();
t.show("monika");
Xyz x=new Xyz();
x.show("jyoti");
}
}
// covariant return type-1
// covariant return type-2
/*08, pt. mt A.MOD = public, cld. mt A.MOD = default */
public class G08 {
public void show(String a){
System.out.println("covariant return type-1");
}
}
class Xyz extends G08{
void show(String a){
System.out.println("covariant return type-2");
}
public static void main(String[] args){
G08 t=new G08();
t.show("monika");
Xyz x=new Xyz();
x.show("jyoti");
}
}
// show(String) in Xyz cannot override show(String) in G08 void show(String a){
// attempting to assign weaker access privileges; was public
/*09, pt A.MOD = protective cld. A.MOD = public */
public class G09 {
protected void show(String a){
System.out.println("protected - public-1");
}
}
class Xyz extends G09{
public void show(String a){
System.out.println("protected - public-2");
}
public static void main(String[] args){
G09 t=new G09();
t.show("monika");
Xyz x=new Xyz();
x.show("jyoti");
}
}
// protected - public-1
// protected - public-2
/*10, pt m/t not throws any e/x, cld only throws unchecked */
public class G11 {
void show(){
System.out.println("parent ok - child only Un checked -1");
}
}
class Xyz extends G11{
void show() throws ArithmeticException{
System.out.println("parent ok - child only Un checked -2");
}
public static void main(String[] args){
G11 t=new G11();
t.show();
Xyz x=new Xyz();
x.show();
}
}
// parent ok - child only Un checked -1
// parent ok - child only Un checked -2
// ArithmeticException , UN-Checked Exception
/*11, pt m/t not throws e/x, cld m/t throws checked e/x */
public class G12 {
void show(){
System.out.println("parent ok - child checked, error -1");
}
}
class Xyz extends G12{
void show() throws Exception{
System.out.println("parent ok - child checked, error -2");
}
public static void main(String[] args){
G12 t=new G12();
t.show();
Xyz x=new Xyz();
x.show();
}
}
// Exception , Checked Exception
// in Xyz cannot override show() in G12 public void show() throws Exception{
// overridden method does not throw Exception
/*12. pt an cld can throws same r/t e/x ( arithmatic )*/
public class G13 {
void show() throws RuntimeException{
System.out.println("parent - child same exception -1");
}
}
class Xyz extends G13{
void show() throws RuntimeException{
System.out.println("parent - child same exception -2");
}
public static void main(String[] args){
G13 t=new G13();
t.show();
Xyz x=new Xyz();
x.show();
}
}
// parent - child same exception -1
// parent - child same exception -2
// Exception , Checked Exception
/*13, pt throws pt e/x , cld throws cld e/x. */
public class G14 {
void show() throws RuntimeException{
System.out.println("parent exception to child exception-1");
}
}
class Xyz extends G14{
void show() throws ArithmeticException{
System.out.println("parent exception to child exception -2");
}
public static void main(String[] args){
G14 t=new G14();
t.show();
Xyz x=new Xyz();
x.show();
}
}
// parent exception to child exception-1
// parent exception to child exception -2
// ArithmeticException child of RuntimeException
// child = if no exception , it also works
/*14, p/t throws cld e/x, cld throws pt e/x */
public class G15 {
void show() throws RuntimeException{
System.out.println("parent exception to child exception-1");
}
}
class Xyz extends G15{
void show() throws Exception{
System.out.println("parent exception to child exception -2");
}
public static void main(String[] args){
G15 t=new G15();
t.show();
Xyz x=new Xyz();
x.show();
}
}
// show() in Xyz cannot override show() in G15 void show() throws Exception{
// overridden method does not throw Exception
// Exception parent of RuntimeException
// in child, equal level or child level exception works
/*15, pt has abs. cls with abs. m/t with concrete m/t , body not defined */
abstract public class G16 {
abstract void display();
void show() {
System.out.println("parent exception to child exception-1");
}
}
class Xyz extends G16{
void show() {
System.out.println("parent exception to child exception -2");
}
public static void main(String[] args){
G16 t=new G16(); // can't create asbtract class m/t
t.show();
Xyz x=new Xyz();
x.show();
}
}
// Xyz is not abstract and does not override abstract method display() in G16 class Xyz extends G16{
/*16, pt has abs, cls with abs. m/t with concrete m/t , body defined */
abstract public class G17 {
abstract void display();
void show() {
System.out.println("abstract class abstract m/t must oR -1");
}
}
class Xyz extends G17{
void display(){} // must override the abstract m/t
void show() {
System.out.println("abstract class abstract m/t must oR -2");
}
public static void main(String[] args){
Xyz x=new Xyz();
x.show();
}
}
// abstract class abstract m/t must oR -2
/*17, pt is itf with abs m/t , body not defined */
interface i1{
void displayi1(); // by default , all m/t are abstract
}
abstract public class G18 {
abstract void display();
void show() {
System.out.println("abstract class abstract m/t must oR -1");
}
}
class Xyz implements i1{
void show() {
System.out.println("abstract class, abstract m/t must oR -2");
}
public static void main(String[] args){
Xyz x=new Xyz();
x.show();
}
}
// Xyz is not abstract and does not override abstract method displayi1() in i1 class Xyz implements i1
/*18, pt is itf with abs. m/t , body defined with pulbic a/m*/
interface i1{
void displayi1(); // by default , all m/t are abstract
}
abstract public class G19 {
abstract void display();
void show() {
System.out.println("abstract class abstract m/t must oR -1");
}
}
class Xyz implements i1{
void displayi1(){} // need to add public also
void show() {
System.out.println("interface m/t -2");
}
public static void main(String[] args){
Xyz x=new Xyz();
x.show();
}
}
// displayi1() in Xyz cannot implement displayi1() in i1
// void displayi1(){} attempting to assign weaker access privileges; was public
/*19, cld cls can call pt cls m/t using super */
public class G20{
void show(){
System.out.println("super-1");
}
}
class Xyz extends G20{
void show(){
super.show(); // points parent m/t
System.out.println("super-2");
}
public static void main(String[] args){
Xyz x=new Xyz();
x.show();
}
}
// super-1
// super-2
// We can call parent class method in overriding method using super keyword.
/*20, Final / Static / Private , Not OR */
public class G21{
final void show(){
System.out.println("final-1");
}
}
class Xyz extends G21{
void show(){
System.out.println("final-2");
}
public static void main(String[] args){
Xyz x=new Xyz();
x.show();
}
}
// show() in Xyz cannot override show() in G21
// void show(){ overridden method is final
/*21, - Static, not oR */
public class G22{
static void show(){
System.out.println("static-1");
}
}
class Xyz extends G22{
void show(){
System.out.println("static-2");
}
public static void main(String[] args){
Xyz x=new Xyz();
x.show();
}
}
// show() in Xyz cannot override show() in G22
// void show(){ overridden method is static
/*22, - Private, not oR */
public class G23{
private void show(){ // private accesibility is within class
System.out.println("private-1");
}
}
class Xyz extends G23{
void show(){
System.out.println("private-2");
}
public static void main(String[] args){
Xyz x=new Xyz();
x.show();
}
}
//private-2
// m/t not override
/*23, Pt M/T Synchronized, Acceptable */
public class G24{
synchronized void show(){
System.out.println("synchronized-1");
}
}
class Xyz extends G24{
void show(){
System.out.println("synchronized-2");
}
public static void main(String[] args){
Xyz x=new Xyz();
x.show();
}
}
// synchronized-2
// The presence of synchronized/strictfp modifier with method have no effect on the rules chronized/stricte, mephosible
// override a non synchronized/strictfp one and vice-versa.
/*24, child m/t synchronized, acceptable */
public class G26{
void show(){
System.out.println("synchronized-1");
}
}
class Xyz extends G26{
synchronized void show(){
System.out.println("synchronized-2");
}
public static void main(String[] args){
G26 g1 = new G26();
g1.show();
Xyz x=new Xyz();
x.show();
}
}
// synchronized-1
// synchronized-2
/*25, Cld Is Strictfp, Version Dependent */
public class G27{
void show(){
System.out.println("strictfp-1");
}
}
class Xyz extends G27{
strictfp void show(){
System.out.println("strictfp-2");
}
public static void main(String[] args){
G27 g1 = new G27();
g1.show();
Xyz x=new Xyz();
x.show();
}
}
// [strictfp] as of release 17, all floating-point expressions are evaluated
// strictly and 'strictfp' is not required strictfp void show(){
/*26, - parent is strictfp, version dependent */
public class G28{
strictfp void show(){
System.out.println("strictfp-1");
}
}
class Xyz extends G28{
void show(){
System.out.println("strictfp-2");
}
public static void main(String[] args){
G28 g1 = new G28();
g1.show();
Xyz x=new Xyz();
x.show();
}
}
// warning: [strictfp] as of release 17, all floating-point expressions are
// evaluated strictly and 'strictfp' is not required strictfp void show(){
/*27, - covarient rule for M/T OR-2 */
class GClass {
public void publicdMt() { /* public aMod can OR */
System.out.println("Public super m/t");
}
protected void protectedMt() { /* protected and public aMod can OR */
System.out.println("Protected super m/t");
}
void defaultMt() { /* protected and public and default aMod can OR */
System.out.println("Default super m/t");
}
private void privateMt() { /* can't OR */
System.out.println("Private super m/t");
}
}
class Subclass extends GClass {
@Override
public void publicdMt() { /* works fine */
System.out.println("Public sub m/t ");
}
@Override
protected void protectedMt() { /* works fine */
System.out.println("Public sub m/t ");
}
@Override
void defaultMt() {
System.out.println("Default sub m/t ");
}
/* @Override can't use this also */
void privateMt() {
System.out.println("Private sub m/t ");
}
public static void main(String[] args){
GClass g1 = new GClass();
g1.protectedMt();
g1.defaultMt();
g1.publicdMt();
// g1.privateMt(); /* error */
Subclass s1 = new Subclass();
s1.privateMt();
s1.protectedMt();
s1.defaultMt();
s1.publicdMt();
}
}
// Protected super m/t
// Default super m/t
// Public super m/t
// Private sub m/t
// Public sub m/t
// Default sub m/t
// Public sub m/t
/*28, - covarient rule for M/T OR-1 */
class GClass{
public static void main(String[] args){
System.out.println("just for check");
}
}
class Animal {
Animal reproduce() {
System.out.println("Animal is reproducing.");
return new Animal();
}
}
class Dog extends Animal {
@Override
Dog reproduce() {
System.out.println("Dog is reproducing.");
return new Dog();
}
}
// just for check
