Program 1- Upcasting and Downcasting
package com.sanjay.java.basic;
class Parent {
/*Parent() {
System.out.println("Parent constructor.");
}*/
public void show() {
System.out.println("I am Parent class method.");
}
}
public class Child extends Parent {
/*
Child() {
System.out.println("Child constructor.");
}*/
public void show() {
System.out.println("I am Child class method.");
}
static void check(Parent p) {
Child t = (Child) p;
t.show();
System.out.println("Down casting done");
}
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
System.out.println("*********Down casting*************");
// CastingTest test=(CastingTest) new Parent(); //Exception in thread
// "main" java.lang.ClassCastException: at run time
Parent b = new Child();
Child.check(b);
System.out.println("*********up casting*************");
Parent obj = new Child();
obj.show();
}
}
Output-
*********Down casting*************
I am Child class method.
Down casting done
*********up casting*************
I am Child class method.
Program 2- Reverse Sentence
package com.sanjay.java.basic;
public class ReverseSentence {
public String doReverse(String str) {
String revStr = "";
String sp[] = str.split(" ");
for (int i = sp.length - 1; i >= 0; i--) {
revStr = revStr + sp[i]+" ";
}
return revStr;
}
public static void main(String arg[]) {
String str = "I live in delhi";
ReverseSentence obj = new ReverseSentence();
String reverse=obj.doReverse(str);
System.out.println("Reverse sentence = " + reverse);
}
}
Output-
Reverse sentence = delhi in live I
Program 3- Reverse String
package com.sanjay.java.basic;
public class ReverseString {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
String str="My Name is sanjay verma";
String rev="";
for(int i=str.length()-1;i>=0;i--){
rev=rev+str.charAt(i);
}
System.out.println(rev);
}
}
Output-
amrev yajnas si emaN yM
Program- 4 Comosition Uses [ Using composition achieve inheritance ]
package com.sanjay.java.basic;
class Test {
public void name() {
System.out.println("I am android profesional.");
}
}
final class MyComposition {
public void show() {
System.out.println("I am Composition method.");
}
}
public class CompositionTest extends Test {
MyComposition composition;
public void display() {
composition = new MyComposition();
composition.show();
}
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
CompositionTest obj = new CompositionTest();
obj.display();
obj.name();
}
}
Output-
I am Composition method.
I am android profesional.
Program 5- Prime Number check
package com.sanjay.java.basic;
public class PrimeNumber {
public void checkPrime(int num) {
int j = 2;
// for (int i = 0; i <= num; i++) {
// while(num<=500){
while (j < num) {
if (num % j == 0) {
break;
} else {
j++;
}
}
// }
if (num == j) {
System.out.println("Prime number -" + num);
} else {
System.out.println("Number is not prime");
}
// }
}
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
PrimeNumber obj = new PrimeNumber();
obj.checkPrime(23);
}
}
Output-
Prime number -23
Program- 6 Palindrome Check
package com.sanjay.java.basic;
public class PalindromeChek {
//
static String mString = "madam";
private boolean isPalindrome(String str) {
int i = str.length() - 1;
int j = 0;
while (i > j) {
if (str.charAt(i) != str.charAt(j)) {
return false;
}
i--;
j++;
}
return true;
}
private void integerValueCheck(int n) {
int r, temp, sum = 0;
//
int n = 454;
temp = n;
while (n > 0) {
r = n % 10;
sum = (sum * 10) + r;
n = n / 10;
}
if (sum == temp) {
System.out.println("Number is palindrome");
} else {
System.out.println("Number not palindrome");
}
}
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
// ********************* STRING CHECK********************************
PalindromeChek obj = new PalindromeChek();
boolean b = obj.isPalindrome("aman");
//System.out.println("string check " + b);
if (b) {
System.out.println("String is palindrome");
} else {
System.out.println("String not palindrome");
}
// **********************INTEGER CHECK*******************************
obj.integerValueCheck(425124);
}
}
Output-
String is palindrome
Number is palindrome
Program -7 (
Armstrong number check)
package com.sanjay.java;
public class ArmStrongNumber {
void getArmStrong(int num) {
int n, sum = 0;
int rem, cube;
n = num;
while (n > 0) {
rem = n % 10;
cube = rem * rem * rem;
sum = sum + cube;
n = n / 10;
}
if (sum == num) {
System.out.println("Armstrong number =" + sum);
}else{
System.out.println("Number not an ArmStrong");
}
}
public static void main(String[] args) {
// TODO Auto-generated method stub
ArmStrongNumber obj = new ArmStrongNumber();
obj.getArmStrong(153);
obj.getArmStrong(155);
}
}
Output-
Program -8 (One interface can extends more than one interface)
package com.sanjay.java;
interface printable{
void print();
}
interface scannable {
void scan();
}
interface functional extends scannable , printable{
void work();
}
class A6 implements functional {
public void print(){System.out.println("print");}
public void scan(){System.out.println("scan");}
public void work(){System.out.println("work");}
public static void main(String args[]){
A6 obj = new A6();
obj.print();
obj.scan();
obj.work();
}
}
Output-
print
scan
work
Program -
9 (
Count number occurrence in array)
public class NumberOccurrance {
public static void main(String[] args) {
// TODO Auto-generated method stub
int[] arr={2,3,4,2,5,6,2,1,3,2,8,9};
int[] solArr=new int[12];
/**
* Here i am creating solArr with 12 length, it initialized all index with 0 value.
* ___________________________________________________
* |_0_|_1_|_2_|_3_|_4_|_5_|_6_|_7_|_8_|_9_|_10_|_11_|
arr[i]= 2 3 4 2 5 6 2 1 3 2 8 9
solArr[arr[i]]=
solArr[arr[0]]=> solArr[2]=1
solArr[arr[1]]=> solArr[3]=1
solArr[arr[2]]=> solArr[4]=1
solArr[arr[3]]=> solArr[2]=1+1 = 2
solArr[arr[4]]=> solArr[5]=1
solArr[arr[5]]=> solArr[6]=1
solArr[arr[6]]=> solArr[2]=2+1 = 3
solArr[arr[7]]=> solArr[1]=1
solArr[arr[8]]=> solArr[3]=1+1 = 2
solArr[arr[9]]=> solArr[2]=3+1 = 4
.
.
So if same number is already in solArr index then increment by 1 in below code.
*/
for(int i=0;i<arr.length;i++){
solArr[arr[i]]+=1;
}
System.out.println("Array elements and it's count");
for (int j = 0; j < solArr.length; j++) {
System.out.println("element "+j +" count "+solArr[j]);
}
if(solArr[2]>=solArr[3]){
System.out.println(2);
}else{
System.out.println(1);
}
}
}
Output-
index 0 count 0
index 1 count 1
index 2 count 4
index 3 count 2
index 4 count 1
index 5 count 1
index 6 count 1
index 7 count 0
index 8 count 1
index 9 count 1
index 10 count 0
index 11 count 0
2
