Hey there! Welcome to ClearUrDoubt.com. In this post, we will look at a Java program to create a JSON file using JSON-simple API. JSON-simple API is used to create and read JSON files in a simple way. Maven dependency for Read more
Hey there! Welcome to ClearUrDoubt.com. In this post, we will look at the program to convert a String into a Map in Java. Consider if a String is having KeyValuePairs delimited by another character, we can split the string and load them Read more
Hey there! Welcome to ClearUrDoubt.com. In this post, we will look at the demonstration of Optional<T> class in Java 8. Optional is introduced in Java 8 mainly to provide a way to avoid Null Pointer Exceptions in the code. Instead of directly Read more
Hey there! Welcome to ClearUrDoubt.com. In this post, we will look at the Custom implementation of the Doubly LinkedList class in Java. Before proceeding further, please go through the below post for a better understanding of Doubly LinkedList. Custom Implementation of Read more
Hey there! Welcome to ClearUrDoubt.com. In this post, we will look at the Custom implementation of the Singly LinkedList class in Java. Simple implementation of Singly LinkedList:
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package com.clearurdoubt.impl; /** * * @author Sai Gowtham Badvity * SinglyLinkedList Implementation * @param <T> type of the object LinkedList holds. * */ public class MySinglyLinkedList<T> { private class Node { T value; Node next; } private Node head = null, tail = null; /** * Add Node to the List * @param val */ public void add(T val) { addLast(val); } /** * Add Node in the beginning the List * @param val */ public void addFirst(T val) { Node newNode = new Node(); newNode.value = val; newNode.next = head; head = newNode; if(tail == null) tail = newNode; } /** * Add Node at the end of the List * @param val */ public void addLast(T val) { if(head == null) { addFirst(val); return; } Node newNode = new Node(); newNode.value = val; newNode.next = null; tail.next = newNode; tail = newNode; } /** * Remove first node */ public void removeFirst() { if(head == null) return; else { head = head.next; } } /** * Remove last node */ public void removeLast() { Node temp = head; while(temp.next != tail) { temp = temp.next; } temp.next = null; tail = temp; } /** * Print the elements */ @Override public String toString() { StringBuilder builder = new StringBuilder(); Node temp = head; do { builder.append( temp.value + " -> "); temp = temp.next; } while(temp.next != null); builder.append( temp.value ); return builder.toString(); } } |
Let’s see the demo of MySinglyLinkedList class:
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package com.clearurdoubt.impl; /** * * @author Sai Gowtham Badvity * Demo of the usage of MySinglyLinkedList * */ public class MySinglyLinkedListDemo { public static void main(String[] args) { MySinglyLinkedList<Integer> myList = new MySinglyLinkedList<Integer>(); myList.add(10); myList.add(20); myList.add(30); myList.addFirst(40); myList.addLast(50); System.out.println(); System.out.println("Elements in the list: " + myList); myList.removeFirst(); System.out.println(); System.out.println("After removing first node: " + myList); myList.removeLast(); System.out.println(); System.out.println("After removing last node: " + myList); myList.addFirst(40); System.out.println(); System.out.println("After adding a new node in the beginning: " + myList); } } |
Output: Happy Learning :). Read more
Hey there! Welcome to ClearUrDoubt.com. In this post, we will look at a program to demonstrate default methods in Interfaces in Java 8. Default methods are introduced in Java 8 to provide a default implementation for methods in an Interface. Using Read more
Hey there! Welcome to ClearUrDoubt.com. In this post, we will look at a Java program to demonstrate Inter-Thread Communication. I would suggest you go through the below link before proceeding with this post. Core Java program to create multiple threads Inter-Thread communication is Read more
Hey there! Welcome to ClearUrDoubt.com. In this post, we will look at a Core Java program to create multiple threads. We can create threads in two ways as below: By implementing the Runnable interface. By extending the Thread class The user can select Read more
Hey there! Welcome to ClearUrDoubt.com. In this post, we will look at a Core Java program to find the longest sub-string in a String without repeated chars. Here is the program:
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package com.clearurdoubt; import java.util.Scanner; /** * * @author clearurdoubt * */ public class FindSubstring { public static void main(String[] args) { System.out.println("Please enter an input string:"); // request user to provide an empty string Scanner in = new Scanner(System.in); // Scanner instance to read the input from console String input = in.nextLine().trim(); // Read the input and trim the spaces around it // Find and print the longest substring. System.out.println("The longest substring in the input \"" + input + "\" is \"" + findLongestSubstring(input) + "\""); in.close(); } /** * Method to find the longest substring without repeated characters * @param input string from user * @return */ private static String findLongestSubstring(String input) { String longest = ""; // Variable for storing the longest substring // Loop through the characters from starting to ending for(int i=0; i < input.length() - 1; i++) { String substr = ""; // Local variable to find the current substring without repeated chars // Loop through characters from index "i" till the end of input for(int j = i; j < input.length() - 1; j++) { char ch = input.charAt(j); // Current character if(substr.indexOf(ch) == -1) // If substr doesn't contain the current character { substr += ch; // Time to append the current char to substr } else { break; // Current char already in the substr, so break out the inner loop } } // Time to check if the local substr is longer than "longest" variable if(longest.length() < substr.length()) { longest = substr; } } return longest; // Return the longest substring } } |
Output: Happy Learning :). Please leave a reply in case Read more
Hey there! Welcome to ClearUrDoubt.com. In this post, we will look at a Spark program to load a table data from Cassandra to Hive using Java. Step 1: Create a table in Cassandra and insert records into it.
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cqlsh:clearurdoubt> CREATE TABLE students( ... id int PRIMARY KEY, ... name text, ... marks int); cqlsh:clearurdoubt> INSERT INTO students (id, name, marks) VALUES (101, 'Sidhu', 92); cqlsh:clearurdoubt> INSERT INTO students (id, name, marks) VALUES (102, 'Sanju', 90); cqlsh:clearurdoubt> INSERT INTO students (id, name, marks) VALUES (103, 'Ram', 45) ; cqlsh:clearurdoubt> INSERT INTO students (id, name, marks) VALUES (105, 'Krishna', 88) ; cqlsh:clearurdoubt> INSERT INTO students (id, name, marks) VALUES (104, 'Mounika', 90) ; cqlsh:clearurdoubt> cqlsh:clearurdoubt> select * from students; id | marks | name -----+-------+--------- 105 | 88 | Krishna 104 | 90 | Mounika 102 | 90 | Sanju 101 | 92 | Sidhu 103 | 45 | Ram (5 rows) cqlsh:clearurdoubt> |
Step 2: Read more