#06 [JAVA] - Java User Input (Scanner), Printf methods

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Sun Apr 18 2021 03:51:56 GMT+0000 (Coordinated Universal Time)

Saved by @ahmedqgqgq #java

public class MyProgram {
	public static void main(String[] args) {
		int f=10;
		System.out.println(f);
	}
}
import java.util.Scanner;
public class MyProgram {
	public static void main(String[] args) {
		Scanner in= new Scanner(System.in);
		System.out.println("Enter number");
		int f=in.nextInt();
		System.out.println("number=="+f);
	}
}
import java.util.Scanner;
public class MyProgram {
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		float n1, n2;
		System.out.println("Please enter the first number:");
		n1 = in.nextFloat();
		System.out.println("Plase enter the second number:");
		n2 = in.nextFloat();
		System.out.println("num1="+n1+"\n"+"num2="+n2);
	}
}
import java.util.Scanner;
public class Ahmedjava {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        float n1, n2;
        System.out.println("Please enter the first number:");
        n1 = in.nextFloat();
        System.out.println("Plase enter the second number:");
        n2 = in.nextFloat();
        System.out.println("num1=" + n1 + "\n" + "num2=" + n2);
        String out1 = String.format("num1=%f num2=%f", n1, n2);
        System.out.println(out1);
        // System.out.printf("num1=%.2f num2=%f",n1,n2);
    }
}
import java.util.Scanner;

public class Ahmedjava {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.println("Enter a value s:");
        String s = in.next();
        System.out.printf("s = %s", s);
    }
}
import java.util.Scanner;
public class Ahmedjava {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.println("Enter a value s:");
        String s = in.nextLinea();
        System.out.printf("s = %S", s);
    }
}
import java.util.Scanner;

public class Ahmedjava {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.println("Enter a value s:");
        char s = in.next().charAt(0);
        System.out.printf("s=%s", s);
    }
}
import java.util.Scanner;
public class Ahmedjava {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n1, n2;
        System.out.println("Enter num1:");
        n1 = in.nextInt();
        System.out.println("Enter num2:");
        n2 = in.nextInt();
        System.out.println("sum=" + (n1 + n2));//not n1+n2
    }
}
import java.util.Scanner;
public class Ahmedjava {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n1, n2, sum;
        System.out.println("Enter num1:");
        n1 = in.nextInt();
        System.out.println("Enter num2:");
        n2 = in.nextInt();
        sum = n1 + n2;
        System.out.println("sum=" + sum);
    }
}
import java.util.Scanner;
public class Ahmedjava {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n1, n2, n3;
        System.out.println("Enter num1:");
        n1 = in.nextInt();
        System.out.println("Enter num2:");
        n2 = in.nextInt();
        System.out.println("Enter num3:");
        n3 = in.nextInt();
        System.out.println("Avg==" + (n1 + n2 + n3) / 3);

    }
}
import java.util.Scanner;

public class Ahmedjava {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n1, n2, n3;
        System.out.println("Enter num1:");
        n1 = in.nextInt();
        System.out.println("Enter num2:");
        n2 = in.nextInt();
        System.out.println("Enter num3:");
        n3 = in.nextInt();
        System.out.println("Avg==" + (n1 + n2 + n3) / 3);

    }
}

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java ahmed

@ahmedqgqgq

Escape Sequences Escape Sequences datatypes datatypes Arithmetic Operators. Arithmetic Operators (Prefix & Postfix). #06 [JAVA] - Java User Input (Scanner), Printf methods Selection Statement ( if - if else - if else if ) 08 [JAVA] - Selection Statement ( Exercises, Practice, Ternary Operator ), Instanceof Method #09 [JAVA] - Selection Statement (Switch Statements) Repetition Control Statement (While Loop) Sentinel and Flag-Controlled While Loops Repetition Control Statement (Do-While Loop) Repetition Control Statement (For Loop) Repetition Control Statement (For Loop) Questions and Exercises in Loops. Branching Statements ( Break/Continue ). Repetition Control Statement (Nested Loops) Branching Statements (Labeled Break / Labeled Continue) Method / Function Part 1 Method / Function Part 2 - Built in Method / Function Overloading Method / Function Recursion/Recursive Methods Part 1 Recursion/Recursive Methods Part 2 One Dimensional Arrays (1D Array) One Dimensional Arrays (1D Array).new One Dimensional Array (Exercises, Practice)Exercises. One Dimensional Array (Char Array)char arrays, One Dimensional Array (Char Array)char arrays, Passing Arrays to Methods.(Arrays) Multidimensional Arrays & Passing Multidimensional Arrays to Methods String & Array String. methods String & Array String. methods

#java #howto #interviewquestions #mobile

How to use Java Swing to create a button

import javax.swing.*;  
public class FirstSwingExample {  
public static void main(String[] args) {  
JFrame f=new JFrame();//creating instance of JFrame  
          
JButton b=new JButton("click");//creating instance of JButton  
b.setBounds(130,100,100, 40);//x axis, y axis, width, height  
          
f.add(b);//adding button in JFrame  
          
f.setSize(400,500);//400 width and 500 height  
f.setLayout(null);//using no layout managers  
f.setVisible(true);//making the frame visible  
}  
}

#java #gfg #geeksforgeeks #lecture #recursion #rope cutting

Rope Cutting Problem

import java.io.*;
import java.util.*;

class GFG 
{
	static int maxCuts(int n, int a, int b, int c)
	{
		if(n == 0) return 0;
		if(n < 0)  return -1;

		int res = Math.max(maxCuts(n-a, a, b, c), 
		          Math.max(maxCuts(n-b, a, b, c), 
		          maxCuts(n-c, a, b, c)));

		if(res == -1)
			return -1;

		return res + 1; 
	}
  
    public static void main(String [] args) 
    {
    	int n = 5, a = 2, b = 1, c = 5;
    	
    	System.out.println(maxCuts(n, a, b, c));
    }
}

#java #interviewquestions #search

How to binary search in Java

import java.util.Stack;

/**
 * Java Program to implement a binary search tree. A binary search tree is a
 * sorted binary tree, where value of a node is greater than or equal to its
 * left the child and less than or equal to its right child.
 * 
 * @author WINDOWS 8
 *
 */
public class BST {

    private static class Node {
        private int data;
        private Node left, right;

        public Node(int value) {
            data = value;
            left = right = null;
        }
    }

    private Node root;

    public BST() {
        root = null;
    }

    public Node getRoot() {
        return root;
    }

    /**
     * Java function to check if binary tree is empty or not
     * Time Complexity of this solution is constant O(1) for
     * best, average and worst case. 
     * 
     * @return true if binary search tree is empty
     */
    public boolean isEmpty() {
        return null == root;
    }

    
    /**
     * Java function to return number of nodes in this binary search tree.
     * Time complexity of this method is O(n)
     * @return size of this binary search tree
     */
    public int size() {
        Node current = root;
        int size = 0;
        Stack<Node> stack = new Stack<Node>();
        while (!stack.isEmpty() || current != null) {
            if (current != null) {
                stack.push(current);
                current = current.left;
            } else {
                size++;
                current = stack.pop();
                current = current.right;
            }
        }
        return size;
    }


    /**
     * Java function to clear the binary search tree.
     * Time complexity of this method is O(1)
     */
    public void clear() {
        root = null;
    }

}

#java #java #arraylists #while-loops #equala

How to insert ArrayList into While-condition?

List<String> songList = new ArrayList<>();
songList.add("Some song"); //Repeat until satisfied

System.out.println("\n\tWelcome! Please choose a song!");
String songChoice = scan.nextLine();
while (!songList.contains(songChoice)) {
    //Do stuff when input is not a recognised song
}

#java #gfg #geeksforgeeks #arrays #practice #frequencycount #frequencies #limitedrange

Frequencies of Limited Range Array Elements

class Solution{
    //Function to count the frequency of all elements from 1 to N in the array.
    public static void frequencyCount(int arr[], int N, int P)
    {
        //Decreasing all elements by 1 so that the elements
        //become in range from 0 to n-1.
        int maxi = Math.max(P,N);
        int count[] = new int[maxi+1];
        Arrays.fill(count, 0);
        for(int i=0;i<N;i++){
            count[arr[i]]++; 
        }
        
        for(int i=0;i<N;i++){
            arr[i] = count[i+1];
        }
    }
}

How to efficiently iterate over each entry in a Java Map

Map<String, String> map = ...
for (Map.Entry<String, String> entry : map.entrySet()) {
    System.out.println(entry.getKey() + "/" + entry.getValue());
}

Print Nested Array in Java

String[][] deepArray = new String[][] {{"John", "Mary"}, {"Alice", "Bob"}};
System.out.println(Arrays.toString(deepArray));
//output: [[Ljava.lang.String;@106d69c, [Ljava.lang.String;@52e922]
System.out.println(Arrays.deepToString(deepArray));

#java #java #2dchar array

How do you check a row in a 2D char array for a specific element and then count how many of that element are in the row? (Java)

private boolean oneQueenPerRow() {
    int foundQueens;
    for (int i = 0; i < board.length; i++) {
        foundQueens = 0;//each loop is a checked row
        for (int j = 0; j < board.length; j++) {
            if (board[i][j] == QUEEN)
                foundQueens++;
        }
        if (foundQueens > 1) return false;
    }
    return true;
}

#java #logic #algorithms #interesting #arrays

Flood Fill Algorithm: Like the bucket tool in Paint app but for multi-dimensional arrays

import java.util.ArrayDeque;
import java.util.Arrays;
import java.util.Queue;

class Pair {
    int x, y;

    public Pair(int x, int y) {
        this.x = x;
        this.y = y;
    }
}

class FloodFill
{
    // Below arrays details all 8 possible movements
    private static final int[] row = { -1, -1, -1, 0, 0, 1, 1, 1 };
    private static final int[] col = { -1, 0, 1, -1, 1, -1, 0, 1 };

    // check if it is possible to go to pixel (x, y) from
    // current pixel. The function returns false if the pixel
    // has different color or it is not a valid pixel
    public static boolean isSafe(char[][] M, int m, int n,
                                int x, int y, char target)
    {
        return x >= 0 && x < m && y >= 0 && y < n
                && M[x][y] == target;
    }

    // Flood fill using BFS
    public static void floodfill(char[][] M, int x, int y, char replacement)
    {
        int m = M.length;
        int n = M[0].length;

        // create a queue and enqueue starting pixel
        Queue<Pair> q = new ArrayDeque<>();
        q.add(new Pair(x, y));

        // get target color
        char target = M[x][y];

        // run till queue is not empty
        while (!q.isEmpty())
        {
            // pop front node from queue and process it
            Pair node = q.poll();

            // (x, y) represents current pixel
            x = node.x;
            y = node.y;

            // replace current pixel color with that of replacement
            M[x][y] = replacement;

            // process all 8 adjacent pixels of current pixel and
            // enqueue each valid pixel
            for (int k = 0; k < row.length; k++)
            {
                // if adjacent pixel at position (x + row[k], y + col[k]) is
                // a valid pixel and have same color as that of current pixel
                if (isSafe(M, m, n, x + row[k], y + col[k], target))
                {
                    // enqueue adjacent pixel
                    q.add(new Pair(x + row[k], y + col[k]));
                }
            }
        }
    }

    public static void main(String[] args)
    {
        // matrix showing portion of the screen having different colors
        char[][] M = {
            "YYYGGGGGGG".toCharArray(),
            "YYYYYYGXXX".toCharArray(),
            "GGGGGGGXXX".toCharArray(),
            "WWWWWGGGGX".toCharArray(),
            "WRRRRRGXXX".toCharArray(),
            "WWWRRGGXXX".toCharArray(),
            "WBWRRRRRRX".toCharArray(),
            "WBBBBRRXXX".toCharArray(),
            "WBBXBBBBXX".toCharArray(),
            "WBBXXXXXXX".toCharArray()
        };

        // start node
        int x = 3, y = 9;   // target color = "X"

        // replacement color
        char replacement = 'C';

        // replace target color with replacement color
        floodfill(M, x, y, replacement);

        // print the colors after replacement
        for (int i = 0; i < M.length; i++) {
            System.out.println(Arrays.toString(M[i]));
        }
    }
}

Finding all classes implementing a specific interface

public <T> List<Class<? extends T>> findAllMatchingTypes(Class<T> toFind) {
    foundClasses = new ArrayList<Class<?>>();
    List<Class<? extends T>> returnedClasses = new ArrayList<Class<? extends T>>();
    this.toFind = toFind;
    walkClassPath();
    for (Class<?> clazz : foundClasses) {
        returnedClasses.add((Class<? extends T>) clazz);
    }
    return returnedClasses;
}

#java #gfg #geeksforgeeks #lecture #sorting #bubblesort

// Optimised Bubble Sort

import java.io.*;

class GFG {
    
    static void bubbleSort(int arr[], int n){
        boolean swapped;
        
        for(int i = 0; i < n; i++){
            
            swapped = false;
            
            for(int j = 0; j < n - i - 1; j++){
                if( arr[j] > arr[j + 1]){
                    
                    // swapping
                    int temp = arr[j];
                    arr[j] = arr[j+1];
                    arr[j+1] = temp;
                    
                    swapped = true;
                    
                }
            }
            if(swapped == false)
            break;
        }
    }
    
	public static void main (String[] args) {
	    int a[] = {2, 1, 4, 3};
	    bubbleSort(a, 4);
	    
	    for(int i = 0; i < 4; i++){
	        System.out.print(a[i] + " ");     // OUTPUT : 1 2 3 4
	    }
	}
}






// Bubble Sort

import java.io.*;

class GFG {
    
    static void bubbleSort(int arr[], int n){
        for(int i = 0; i < n; i++){
            for(int j = 0; j < n - i - 1; j++){
                if( arr[j] > arr[j + 1]){
                    
                    // swapping
                    int temp = arr[j];
                    arr[j] = arr[j+1];
                    arr[j+1] = temp;
                    
                }
            }
        }
    }
    
	public static void main (String[] args) {
	    int a[] = {2, 1, 4, 3};
	    bubbleSort(a, 4);
	    
	    for(int i = 0; i < 4; i++){
	        System.out.print(a[i] + " ");     // OUTPUT : 1 2 3 4
	    }
	}
}

#java #gfg #geeksforgeeks #lecture #sorting #selectionsort

import java.io.*;

class GFG {
    
    static void selectionSort(int arr[], int n){
        for(int i = 0; i < n; i++){
            int min_ind = i;
            
            for(int j = i + 1; j < n; j++){
                if(arr[j] < arr[min_ind]){
                    min_ind = j;
                }
            }
            
            int temp = arr[i];
            arr[i] = arr[min_ind];
            arr[min_ind] = temp;
        }
    }
    
	public static void main (String[] args) {
	    int a[] = {2, 1, 4, 3};
	    selectionSort(a, 4);
	    
	    for(int i = 0; i < 4; i++){
	        System.out.print(a[i] + " ");    // OUTPUT : 1 2 3 4
	    }
	}
}

Intent to Start New Activity in Android Studio

// IntendedActivity - the file you wish to open
// CurrentActivity - the file where this code is placed  

Intent intent = new Intent (this, IntendedActivity.class);
    CurrentActivity.this.startActivity(intent);

Insertion Sort in Java

 public void sort(int array[]) { 
     for (int i = 1; i < array.length; i++) { 
          int key = array[i]; 
          int j = i - 1; 
          while (j >= 0 && array[j] > key) { 
              array[j + 1] = array[j]; 
              j = j - 1; 
          } 
          array[j + 1] = key; 
      } 
 }

> More steps

Storing data in SQLite Database in android

public class LocalDatabase extends SQLiteOpenHelper {
         
    private static final String mDatabaseName = "LocalDatabase";
    private static final int mDatabaseVersion = 1;

public LocalDatabase(Context context) {
        super(context, mDatabaseName, null, mDatabaseVersion);
        SQLiteDatabase db = this.getWritableDatabase();
    }      

}

> More steps

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