My Programming Blog

 In this Java network programming tutorial, you will learn how to develop a simple socket server program. Server.java package simple_tcp; import java.io.BufferedReader; import java.io.InputStreamReader; import java.io.OutputStreamWriter; import java.io.PrintWriter; import java.net.ServerSocket; import java.net.Socket; public class Server { public Server() throws Exception { ServerSocket server_socket = new ServerSocket(2020); //opening a new port System.out.println("Port 2020 is open."); Socket socket = server_socket.accept(); System.out.println("Client " + socket.getInetAddress() + " has connected."); // I/O buffers: BufferedReader in_socket = new BufferedReader(new InputStreamReader (socket.getInputStream())); PrintWriter out_socket = new PrintWriter(new OutputStreamWriter (socket.getOutputStream()), true); out_socket.println("Welcome!...

Finding min or max value in premative array import java.util.*; class cf { static Scanner input = new Scanner(System.in); public static void main(String[] args) { Integer[] arr = {2,3,1,5,3,61,12}; int max = Collections.max(Arrays.asList(arr)); int min = Collections.min(Arrays.asList(arr)); System.out.println(max); System.out.println(min); } } Output : 61 1

Solving Factorial of number by using BigInteger in Java import java.util.*; import java.math.BigInteger; class cf { static HashMap<BigInteger,BigInteger> list = new HashMap<>(); static BigInteger extraLongFactorials(int n) { BigInteger N = new BigInteger(String.valueOf(n)); if(list.containsKey(N)) return list.get(N); if(n==1 || n==2 || n==0) return N; else { BigInteger ans = N.multiply(extraLongFactorials(n-1)); list.put(N,ans); return list.get(N); } } static Scanner input = new Scanner(System.in); public static void main(String[] args) { try { int n = input.nextInt(); System.out.println(extraLongFactorials(n)); } catch(Exception e){ return; } } } Output : 100 9332621544394415268169923885626670049071596826438162146859296389521759999322991560894146397...

 Modifying variables inside java lambdas. Integer list[] = {1,2,3,4,5,6,7,8}; int index = 0; Arrays.asList(list).forEach(e -> { System.out.println(e+" at index "+index); index++; }); Error : maze2.java:22: error: local variables referenced from a lambda expression must be final or effectively final System.out.println(e+" at index "+index); ^ maze2.java:23: error: local variables referenced from a lambda expression must be final or effectively final index++; ^ Solution : Integer list[] = {1,2,3,4,5,6,7,8}; int[] index = {0}; Arrays.asList(list).forEach(e -> { System.out.println(e+" at index "+index[0]); index[0]++; }); Output : 1 at index 0 2 at index 1 3 at index 2 4 at index 3 5 at index 4 6 at index 5 7 at index 6 8 at index 7

 Maze Solver program in Java.  import java.util.*; import java.io.*; class maze2 { static Scanner input = new Scanner(System.in); public static void main(String[] args) { Integer arr[][] = {{0,0,0,0,9}, {1,0,0,1,0},              {0,1,1,0,0}, {1,0,1,1,1}, {8,0,0,0,0}}; int size = arr.length*arr[0].length; ArrayList<ArrayList<Integer>> maze = new ArrayList<ArrayList<Integer>>(size); int[] index = {0}; Arrays.asList(arr).forEach(row -> { maze.add(new ArrayList<Integer>()); Arrays.asList(row).forEach(item -> maze.get(index[0]).add(item)); index[0]++; }); Graph graph = new Graph(size,maze); // System.out.println(maze); System.out.println("\ndfs"); graph.dfs(20,4); } } class Graph { int V ; int start , end ; ArrayList<ArrayList<Integer>> list = n...

Graph Data Structure implementation in java import java.util.*; class Graph { ArrayList<ArrayList<Integer>> list = new ArrayList<ArrayList<Integer>>(); int V; public Graph(int v){ this.V = v; for(int i=0;i<V;i++) list.add(new ArrayList<Integer>()); } void add(int s , int d){ list.get(s).add(d); list.get(d).add(s); } void display(){ for(int i=0;i<V;i++){ System.out.print(i+" : "); for(int x : list.get(i)) System.out.print(" => "+x); System.out.println(""); } } void dfs(int start){ boolean visited[] = new boolean[V]; _dfs(start,visited); } void _dfs(int node , boolean[] visited){ visited[node] = true; System.out.print(node+" => "); for(int x : list.get(node)){ if(!visited[x]){ _dfs(x,visited); } } } void bfs(int start){ boolean visited[] = new boolean[V]; Queue<Integer> q = new LinkedList<Integer>(); q.add(start); vis...

Java program to List all files in a directory and nested sub-directories import java.io.*; import java.util.*; class solution { static void yRec(File[] arr,int index , int level){ if(index==arr.length ) return; for(int i=0;i level;i++) System.out.print("\t"); if(arr[index].isFile()) { System.out.println("File : "+arr[index].getName()+" of size : "+arr[index].length()+" bytes"); } else if(arr[index].isDirectory()){ File[] subArr = arr[index].listFiles(); if(subArr.length == 0) return; System.out.println("[" + arr[index].getName() + "]" + " has "+subArr.length+" files. Path : "+subArr[0].getParent()); yRec(subArr,0,level+1); } yRec(arr,++index,level); } public static void main(String[] args) { String path = "D:\\web\\assets\\fonts"; // String path = args[0...

Solving Graph in Java import java.util.*; class Graph { LinkedList list[] ; public Graph(int V){ list = new LinkedList[V]; for(int i=0;i V;i++) list[i] = new LinkedList (); } void addEdge(int source , int destination){ list[source].add(destination); list[destination].add(source); } public int bfs(int source , int destination){ boolean visited[] = new boolean[list.length]; int parent[] = new int[list.length]; Queue q = new LinkedList (); q.add(source); parent[source] = -1; visited[source] = true; while(!q.isEmpty()){ int curr = q.poll(); if(curr == destination) break; for(int neighbor : list[curr]){ if(!visited[neighbor]){ visited[neighbor] = true; q.add(neighbor); parent[neighbor] = curr; } } } int cur = destination; int distance = 0; while(parent[cur] != -1) { ...

import java.util.*; class solution { static Scanner input = new Scanner(System.in); static Node createTree(){ Node root = null; System.out.println("Enter Data : "); int data = input.nextInt(); if(data == -1) return root; root = new Node(data); System.out.println("Enter to left of "+data); root.left = createTree(); System.out.println("Enter to right of "+data); root.right = createTree(); return root; } static void inOrder(Node root){ if(root == null) return; inOrder(root.left); System.out.println(root.data+"=>"); inOrder(root.right); } static void postOrder(Node root){ if(root == null) return; postOrder(root.left); postOrder(root.right); System.out.println(root.data+"=>"); } static void preOrder(Node root){ if(root == null) return; System.out.println(root.data+"=...

My Program to create Binary Tree and print sorted output class Node { int data ; Node left,right; Node(int value) { this.data = value; left = null; right = null; } } class myTree { Node root ; myTree () { root = null ; } // apending to tree void add(int value) { if(root==null) { root = new Node(value); System.out.println("Root created = "+root.data); return; } _add(root,value); } void _add(Node pointer, int value) { if(pointer.data < value) { if(pointer.right != null) { _add(pointer.right , value); } else { pointer.right = new Node(value); System.out.println("Inserted "+pointer.right.data+" to right of "...

I wrote this code for codechef march 2021 contest for "college life 4" problem but was unsucessfull to solve it Link of the problem here This is for the futute me. Try to solve this problem if you think you are smart import java.util.*; import java.util.stream.*; import java.io.*; class multiMap { long key; long value; multiMap(long key,long value){ this.key = key; this.value = value; } void display(){ System.out.println("key : "+key+"\t value : "+value); } } class MyList{ List keyMapList = new ArrayList (); public MyList(long a , long b,long c,long A,long B,long C){ keyMapList.add(new multiMap(a,A)); keyMapList.add(new multiMap(b,B)); keyMapList.add(new multiMap(c,C)); keyMapList = keyMapList.stream().sorted(Comparator.comparing(e->e.key)).collect(Collectors.toList()); } void pop(){ keyMapList.remove(0); } long getValue(long index){ return keyMapList.get((int)index).value; } long getKey(){ return keyMapList.get...