Here’s a collection of basic Java code snippets that cover common interview topics, including data structures, algorithms, and object-oriented programming. These examples can serve as a good foundation for preparation.
1. Hello World Program
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello, World!");
}
}
2. Fibonacci Series
public class Fibonacci {
public static void main(String[] args) {
int n = 10; // number of terms
int a = 0, b = 1;
System.out.print("Fibonacci Series: ");
for (int i = 1; i <= n; i++) {
System.out.print(a + " ");
int next = a + b;
a = b;
b = next;
}
}
}
3. Factorial Calculation (Iterative)
public class Factorial {
public static void main(String[] args) {
int number = 5; // Example number
long fact = 1;
for (int i = 1; i <= number; i++) {
fact *= i;
}
System.out.println("Factorial of " + number + " is: " + fact);
}
}
4. Palindrome Check
public class Palindrome {
public static void main(String[] args) {
String str = "madam";
String reversed = new StringBuilder(str).reverse().toString();
if (str.equals(reversed)) {
System.out.println(str + " is a palindrome.");
} else {
System.out.println(str + " is not a palindrome.");
}
}
}
5. Finding the Largest Element in an Array
public class LargestElement {
public static void main(String[] args) {
int[] arr = {3, 5, 7, 2, 8};
int largest = arr[0];
for (int num : arr) {
if (num > largest) {
largest = num;
}
}
System.out.println("Largest element: " + largest);
}
}
6. Basic Class and Object
class Dog {
String name;
Dog(String name) {
this.name = name;
}
void bark() {
System.out.println(name + " says Woof!");
}
}
public class Main {
public static void main(String[] args) {
Dog dog = new Dog("Buddy");
dog.bark();
}
}
7. Sorting an Array (Bubble Sort)
public class BubbleSort {
public static void main(String[] args) {
int[] arr = {5, 3, 8, 4, 2};
int n = arr.length;
boolean swapped;
for (int i = 0; i < n - 1; i++) {
swapped = false;
for (int j = 0; j < n - 1 - i; j++) {
if (arr[j] > arr[j + 1]) {
int temp = arr[j];
arr[j] = arr[j + 1];
arr[j + 1] = temp;
swapped = true;
}
}
if (!swapped) break; // Stop if no swaps occurred
}
System.out.print("Sorted array: ");
for (int num : arr) {
System.out.print(num + " ");
}
}
}
8. Check for Prime Number
public class PrimeCheck {
public static void main(String[] args) {
int number = 29; // Example number
boolean isPrime = true;
for (int i = 2; i <= Math.sqrt(number); i++) {
if (number % i == 0) {
isPrime = false;
break;
}
}
System.out.println(number + (isPrime ? " is a prime number." : " is not a prime number."));
}
}
9. String Reversal
public class StringReverse {
public static void main(String[] args) {
String str = "Hello";
String reversed = new StringBuilder(str).reverse().toString();
System.out.println("Reversed string: " + reversed);
}
}
10. Finding the Second Largest Element in an Array
public class SecondLargest {
public static void main(String[] args) {
int[] arr = {5, 3, 8, 4, 2};
int largest = Integer.MIN_VALUE;
int secondLargest = Integer.MIN_VALUE;
for (int num : arr) {
if (num > largest) {
secondLargest = largest;
largest = num;
} else if (num > secondLargest && num < largest) {
secondLargest = num;
}
}
System.out.println("Second largest element: " + secondLargest);
}
}
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