Wednesday, 12 April 2023
Beginner Level Java programs
Array Examples:
1. Program to find the sum of all elements in an array:
public class ArraySum {
public static void main(String[] args) {
int[] arr = {2, 4, 6, 8, 10};
int sum = 0;
for (int i = 0; i < arr.length; i++) {
sum += arr[i];
}
System.out.println("Sum of elements in array: " + sum);
}
}
2. Program to find the maximum element in an array:
public class ArrayMax {
public static void main(String[] args) {
int[] arr = {2, 4, 6, 8, 10};
int max = arr[0];
for (int i = 1; i < arr.length; i++) {
if (arr[i] > max) {
max = arr[i];
}
}
System.out.println("Maximum element in array: " + max);
}
}
3. Program to find the minimum element in an array:
public class ArrayMin {
public static void main(String[] args) {
int[] arr = {2, 4, 6, 8, 10};
int min = arr[0];
for (int i = 1; i < arr.length; i++) {
if (arr[i] < min) {
min = arr[i];
}
}
System.out.println("Minimum element in array: " + min);
}
}
4. Program to search for an element in an array:
public class ArraySearch {
public static void main(String[] args) {
int[] arr = {2, 4, 6, 8, 10};
int num = 8;
boolean found = false;
for (int i = 0; i < arr.length; i++) {
if (arr[i] == num) {
found = true;
break;
}
}
if (found) {
System.out.println(num + " found in array");
} else {
System.out.println(num + " not found in array");
}
}
}
5. Program to sort an array in ascending order:
public class ArraySort {
public static void main(String[] args) {
int[] arr = {10, 2, 8, 6, 4};
int temp;
for (int i = 0; i < arr.length; i++) {
for (int j = i + 1; j < arr.length; j++) {
if (arr[i] > arr[j]) {
temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
}
}
System.out.println("Sorted array in ascending order:");
for (int i = 0; i < arr.length; i++) {
System.out.print(arr[i] + " ");
}
}
}
For loop-based programs
6. Program to print the numbers from 1 to 10:
public class PrintNumbers {
public static void main(String[] args) {
for (int i = 1; i <= 10; i++) {
System.out.print(i + " ");
}
}
}
7. Program to print the even numbers from 1 to 20:
public class PrintEvenNumbers {
public static void main(String[] args) {
for (int i = 2; i <= 20; i += 2) {
System.out.print(i + " ");
}
}
}
8. Program to print the sum of the numbers from 1 to 100:
public class SumNumbers {
public static void main(String[] args) {
int sum = 0;
for (int i = 1; i <= 100; i++) {
sum += i;
}
System.out.println("Sum of numbers from 1 to 100: " + sum);
}
}
8. Program to print the multiplication table of a number:
import java.util.Scanner;
public class MultiplicationTable {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.print("Enter a number: ");
int num = input.nextInt();
for (int i = 1; i <= 10; i++) {
System.out.println(num + " x " + i + " = " + (num * i));
}
}
}
9. Program to print a right-angled triangle using asterisks:
import java.util.Scanner;
public class RightTriangle {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.print("Enter the height of the triangle: ");
int height = input.nextInt();
for (int i = 1; i <= height; i++) {
for (int j = 1; j <= i; j++) {
System.out.print("*");
}
System.out.println();
}
}
}
While loop-based programs
10. Program to print the numbers from 1 to 10:
public class PrintNumbers {
public static void main(String[] args) {
int i = 1;
while (i <= 10) {
System.out.print(i + " ");
i++;
}
}
}
11. Program to print the sum of the numbers from 1 to 100:
public class SumNumbers {
public static void main(String[] args) {
int sum = 0;
int i = 1;
while (i <= 100) {
sum += i;
i++;
}
System.out.println("Sum of numbers from 1 to 100: " + sum);
}
}
12. Program to find the factorial of a number:
import java.util.Scanner;
public class Factorial {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.print("Enter a number: ");
int num = input.nextInt();
int factorial = 1;
int i = 1;
while (i <= num) {
factorial *= i;
i++;
}
System.out.println("Factorial of " + num + " = " + factorial);
}
}
Do While loop-based programs
13. Program to print the sum of the numbers from 1 to 100:
public class SumNumbers {
public static void main(String[] args) {
int sum = 0;
int i = 1;
do {
sum += i;
i++;
} while (i <= 100);
System.out.println("Sum of numbers from 1 to 100: " + sum);
}
}
14. Program to ask the user for a password until it matches a predetermined password:
import java.util.Scanner;
public class Password {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
String password = "password123";
String userPassword;
do {
System.out.print("Enter the password: ");
userPassword = input.nextLine();
} while (!userPassword.equals(password));
System.out.println("Password accepted!");
}
}
Class and object-based programs
15. Program to create a simple class and object:
public class MyClass {
int myVariable;
public static void main(String[] args) {
MyClass obj = new MyClass();
obj.myVariable = 10;
System.out.println(obj.myVariable);
}
}
16. Program to create a class with a constructor
public class Person {
String name;
int age;
public Person(String name, int age) {
this.name = name;
this.age = age;
}
public static void main(String[] args) {
Person person = new Person("John", 30);
System.out.println("Name: " + person.name);
System.out.println("Age: " + person.age);
}
}
17. Program to create a class with methods
public class Rectangle {
int length;
int width;
public Rectangle(int length, int width) {
this.length = length;
this.width = width;
}
public int area() {
return length * width;
}
public int perimeter() {
return 2 * (length + width);
}
public static void main(String[] args) {
Rectangle rect = new Rectangle(5, 7);
System.out.println("Area: " + rect.area());
System.out.println("Perimeter: " + rect.perimeter());
}
}
Sunday, 19 March 2023
50 Common Java Interview Programs
Here is a list of Java programs commonly asked about during interviews:
1. Fibonacci series
Program to display any given number of integers of the Fibonacci series. In the Fibonacci series, each number is equal to the sum of the two numbers that precede it.
2. Checking for prime number
Program to verify whether a given number is a prime or composite.
3. String palindrome
Program to verify whether a given string is a palindrome or not. A string is a palindrome if it is equal to the reverse of itself.
4. Integer palindrome
Program to verify whether a given integer is a palindrome or not.
5. Armstrong number
Program to verify whether a given number is an Armstrong number. An Armstrong number is equal to the sum of the cubes of its digits.
6. Avoiding deadlocks
Program where a resource can be accessed by more than one thread, without encountering a deadlock. To avoid deadlocks, you are required to procure resources in a certain order and ensure that they are released in reverse order.
7. Factorial
Program to calculate and display the factorial of any given number.
8. Reversing strings
Program to reverse the order of characters in any given string.
9. Removing repeated elements from an array
Program to identify and remove all repeated elements from an array. Arrays could be of various types like integer, character or string.
10. Printing patterns
Program to print a given pattern composed of ASCII characters. The solution is required to employ an effective algorithm, as opposed to directly printing the pattern as it is.
11. Printing repetitive characters in a string
Program to identify and print all repeated characters of a string.
12. Finding the greatest common denominator of two numbers
Program to print the greatest common denominator of any two given numbers.
13. Finding the square root of a number
Program to print a given number's square root without employing the math.sqrt() function.
14. Reversing an array in place
Program to reverse the order of elements in a string, integer or character array.
15. Reversing the order of words in a sentence
Program to reverse the order of words in any given sentence.
16. Determining leap year
Program to determine whether a given year is a leap year or not.
17. Performing binary search
Program to perform binary search for a given character/integer within a sorted array. In a binary search, the search interval is repeatedly divided into half with every iteration.
18. Checking for anagrams
Program to check if two given strings are anagrams. An anagram is of the same length and is composed of the same characters, but in a different order.
19. Designing a vending machine
Program to create a vending machine interface based on a given set of guidelines. This is a popular OOAD (Object-Oriented Analysis and Design) problem that is frequently asked in Java interviews.
20. Reversing a number
Program to print any given number with the digits in reverse order.
21. Finding the first unique character of a string
Program to identify and print the first unique character in any given string.
22. Finding the middle element of a linked list
Program to print the middle element of a linked list. You may be required to execute this with a single-pass algorithm, meaning the program would read the input only once before running iterations.
23. Performing pre-order traversal
Program to perform pre-order traversal of a hierarchical data structure. Hierarchical data structures like trees can be traversed in multiple ways. Linear data structures like arrays, linked lists, queues and stacks can only be traversed in one logical way.
24. Performing pre-order traversal without recursion
Program to perform pre-order traversal of a tree without recursion. Recursion in Java involves a function/method calling itself within the code.
25. Performing in-order traversal
Program to perform in-order traversal of a hierarchical data structure.
26. Performing in-order traversal without recursion
Program to perform in-order traversal of a tree, employing an iterative solution. Iteration, an alternative to recursion, involves a loop being repeatedly executed till a specific condition is met.
27. Performing post-order traversal
Program to perform post-order traversal of a hierarchical data structure.
28. Performing post-order traversal without recursion
Program to perform post-order traversal of a tree, employing an iterative solution.
29. Printing all leaves of a binary tree
Program to print the values of all leaves in a binary tree. Additionally, you may be asked to print the values in a certain order or hierarchy.
30. Sorting an array using quick-sort
Program to sort a given array of integers using the quick-sort algorithm.
31. Performing insertion sort
Program to sort a given array using the insertion sort algorithm.
32. Performing bubble sort
Program to sort a given array using the bubble sort algorithm.
33. Transposing a matrix
Program to print the transpose of a given matrix. A transpose of a matrix has all its rows and columns interchanged.
34. Printing all permutations of a string
Program to print all character arrangement permutations for any given string.
35. Reversing a string in place
Program to reverse the order of characters in any given string. But, the reversing has to be done in place, meaning the solution is not required to involve creating a duplicate string for reversal.
36. Adding matrices
Program to add any two given matrices and print the result.
37. Multiplying matrices
Program to multiply any two given matrices and print the result.
38. Removing spaces in a string
Program to identify and remove all white spaces in a given string of characters.
39. Reversing a linked list
Program to reverse the order of contents of a singly linked list.
40. Finding the length of a linked list
Program to determine the length of a singly linked list in one iteration of the code.
41. Checking for loops in a linked list
Program to check whether a given linked list contains a loop or not. Corrupt linked lists can sometimes have two nodes pointing to the same location, thereby forming a cycle or loop.
42. Finding the start of looping in a linked list
Program to identify and print the starting instance of looping in a linked list.
43. Finding the middle element of a linked list
Program to determine and print the middle element(s) of a linked list.
44. Finding the nth element from the tail of a linked list
Program to find the nth element from the end of a given linked list, where n is a variable value provided by the user. You may be required to find a solution that does not involve multiple iterations.
45. Converting a linked list to a binary tree
Program to convert a doubly linked list to a binary tree.
46. Sorting a linked list
Program to sort a given linked list in ascending or descending order of values in each node.
47. Performing bucket sort
Program to sort the contents of a given array using the bucket sort algorithm. Bucket sort is a linear sorting algorithm that requires you to know the highest value present in the array before sorting it.
48. Performing counting sort
Program to sort the contents of a given array using the counting sort algorithm. Counting sort is also a linear sorting algorithm like bucket sort, and it helps to know the subtle differences between the two.
49. Performing merge sort
Program to sort the contents of a given array using the merge sort algorithm. You may be required to provide a recursive or iterative solution, depending on what is needed.
50. Checking if two strings are rotations of each other
Program to determine whether any two given strings are rotations of each other. For example, zxy is a rotation of xyz, but zyx is not.
Solutions to the above program will be updated soon.
Sunday, 2 April 2017
Java Concepts required for developing Android apps
In the previous posts, we have learned the software setup and emulator creations, which are very mandatory for the Android app development.
In this post i am going to tell about what are the java concepts required to develop android apps.
Yes, the android apps are created using java programming , so we need to learn the some Java Concepts to create Android apps.
The Android app development is done using two things.
1.Java code to implement the app functionality
2. XML code to design the User Interface( UI ).
In java there are lots of concepts but we do not need all the concepts to develop simple android apps.
Following concepts are enough to develop an android app:
A simple Info-graphic:
1. Basic programming Concepts. ( this is just fundamentals)
2.Data Types
3.Operators
4.Control Statements(this concept is very important)
5.OOPS (Object Oriented Programming)
6. String Handling
7.Array List
8.Basics of Multi threading (For advanced apps)
9.Basics of Exception Handling (For advanced apps)
If you want to learn java no need of any programming experience before. Just by reading some below post you can easily learn Java.
First you need to be familiar with programming for that purpose read some simple C programming...
1. How to run a C program
2. How to add 2 numbers in C
3. Decision Control Statements
4. Loop Control Statements
If you are already familiar with this concept just, skip to start learning java.
After becoming familiar with this fundamentals let start to learn about java.
1. How to Run a Java Program
2.How to add 2 numbers in java
3.How to get input from the user
4. Classes and Objects in Java
If you already know the above concepts just start learning the required concepts.
Practice the above concepts till you become familiar with that.
After that start to learn the Required Java Concepts for developing android applications.
There is a perfect blog to learn all Java concepts that is www.javatpoint.com .
This blog will provide A-Z knowledge in java.
You can learn what you want , try to first complete the above mentioned required java concepts required to develop android apps , then if you want you can learn more.
Read here:
How to develop Android apps
Saturday, 13 February 2016
Data types in Java
 |
- Primitive Data types
- Reference Data types
- For representing the whole numbers, integer data type is used. Like integer short, long and byte are also used for representing whole numbers.
- But they are different in their length.
- The range of int data type is from -2,147,483,648 to 2,147,483,647.
- Default integer type value is 0.
- The size of integer Data Type is 4 bytes.
- If integer data type is not sufficient, long is used to represent large values than the integer.
- The range of this data type is from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807.
- The default value of this Data Type is 0L.
- The size of long Data Type is 8 bytes.
- Short can be used for representing short values (whole numbers).
- Its range is from -32,768 to 32,767.
- The default value of this Data Type is 0.
- The size of short Data Type is 2 bytes.
- This is the smallest data type for representing whole numbers.
- Byte Data Type ranges from -128 to 127.
- Its default value is 0.
- The size of this Data Type is one byte.
- Float and double are used for representing the decimal point numbers such as 2819.248.
- These data types are also called as Real types.
- The default value of Float is 0f.
- The size of this Data Type is 4 bytes.
- The double data type is also same as Float, used for representing decimal point numbers larger than Float.
- Ranges from to.
- The default value of the double is 0d.
- The size of this Data Type is 8 bytes.
- The boolean data type can take Boolean values true and false in the form of 0s and 1s.
- A Boolean variable can be assigned to a Boolean value or to an expression which returns a Boolean value.
- Its default value is ‘false’.
- The character is a data type that allows single character (mostly alphabets but it allows any type of letters) to scan and print.
- The size of character data type is 2 bytes.
- Its default value is “\u0000”.
Java Classes Methods and Objects
Friday, 22 January 2016
Java Classes Methods and Objects
Hello guys ,
In this post I am going to tell about what are classes , methods and objects in Java.
Classes, Methods and Objects are playing the important key role in creating a JAVA program. A programmer needs to know all about these concepts.
Let me tell the abstract meaning for Classes , methods and objects.
Consider the class as your house door’s locker ,
Consider the method as the things in your home.
and consider the objects as the key
If you need to access the things (i.e methods) inside your home (i.e classes)you need to open the door of the house.
In order to open the door of the house we need a key to open the door.
That key is called as objects.
This is the basic concept happening in the coding part logically.
Classes:
A class is defined as an entity that allows data and functions to work together, A class is considered as the user defined reference Data Type.
Predefined primitive Data Types are only limited and not used to represent real world things. But a class can represent real world entities through objects.
For example there is no Data Type to describe properties of a car, or a computer etc. A class Data Type only describes these things.
JAVA program is composed of full of classes, A JAVA program must have a main class containing main() method. Even the main() method also must be inside the class. So classes are more important. A class can have any number of objects.
JAVA allows accessing of one class’s method from another class, one of the main use of object creation is to initiate a class.
Syntax:
class class_name
{
public method1()
{....}
public method2()
{.....}
public static void main(String args[])
{....}
}
For the easy for understanding consider the example
class home
{
public fan()
{ ...
}
public static void main(String args[])
{
....
}
}
class home we already seen in the picture
As described above, a class can have several methods. In this example the
class home has method method fan.
Methods:
To perform various functions inside the class, various methods are created, if we enter various operations under single method, then that will increase the complexity level like Structural language(C Language).
For this reason different
methods are created based on the usage.
Member function provides the controlled access to the data members (Methods
are also called as member functions and Variables are also called as Data
Members).
Syntax:
Method_name()
{
//variables
//functions
}
In method name the closed bracket must present"( )"
In our example the method is
public void fan()
{
System.out.println(“method fan is accessed”);
}
The program after defining the method is given below
import java.io.*;
class house
{
public void
fan()
{
System.out.println("method fan is accessed");
}
public
static void main(String args[])
{
}
}
Now we are clear about what are classes and methods, let we learn how to access the methods inside the class.
The methods in the class is accessed from the main method public
static void main with the help of the objects ( key
).
OBJECTS:
The basic definition from all the books and references for object is "Object is a real-world entity" the reason is, objects can represent a name, or a place or any item that a program handles.
For example if the class is computer( class computer), monitor,
keyboard, hardware and software will be objects of computer class.
While considering Procedural Oriented Programming Languages understanding
the programming flow of the large program seems to be more difficult.
In Object
Oriented Languages, programming and understanding the concept of large programs
is very easy.
Object Oriented means, all the parts or components are in the form of objects and classes. So what is OBJECT( a main block in JAVA)Object is an instance of a class.
Using objects we can access the member
variables (Variables of different methods) and member functions ( or methods)
of a class.
For Example:
Objects can be like flowers, rose, man or anything that used in the real
world.
Objects are the instantiations for class.
Object creation:
class_name object_name=new class_name();
(OR)
class_name object_name;
object_name = new
class_name();
Example:
house h=new house();
(OR)
house h;
h = new house();
class_name object_name;
object_name = new
class_name();
house h=new house();
h = new house();
But exactly the meaning is object created from these above statements does not have any name, here h is the reference variable that holds the address of the object created for class house.
Let us see the full program in detail
import java.io.*;
class house // your house
public void fan() // fan inside your house{
{
System.out.println("method fan is accessed");
}
public static void main(String args[])
{
house h=new house();// object creation (i.e key for your house to access fan)
h.fan();// accessing the method fan by the object h
}
I hope now you are clear about the Java Classes, methods and objects.}
