datatypes

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Sat Apr 17 2021 02:13:09 GMT+0000 (UTC)

Saved by @ahmedqgqgq #java

public class MyProgram {
	public static void main(String[] args) {
		 int x=1;
		  System.out.println(x);
	}
}
public class MyProgram {
	public static void main(String[] args) {
		byte x = -127;//127<_>-127
		System.out.println(x);
	}
}
public class MyProgram {
	public static void main(String[] args) {
		short x = 32767; // -32768<_>32767
		System.out.println(x);
	}
}
public class MyProgram {
	public static void main(String[] args) {
		short x = 10; 
		System.out.println("x="+x);
	}
}
public class MyProgram {
	public static void main(String[] args) {
		int x;//can take 2147483647 value
		System.out.println(Integer.MAX_VALUE);
	}
}
public class MyProgram {
	public static void main(String[] args) {
		int x;// can take -2147483648 value
		System.out.println(Integer.MIN_VALUE);
	}
}
public class MyProgram {
	public static void main(String[] args) {
		float x = 2.5f;// can take 3.4028235E38 VALUE
		System.out.println(x);
		System.out.println(Float.MAX_VALUE);
		float y=2.1234567777f;
		System.out.println(y);
	}
}
public class MyProgram {
	public static void main(String[] args) {
		double x = 2.123456789123456f;//1.79769331348623157E308;
		System.out.println(x);
		System.out.println(Double.MAX_VALUE);
	}
}
public class MyProgram {
	public static void main(String[] args) {
		long x = 21474836488L;
		System.out.println(x);
		System.out.println(Long.MAX_VALUE);
	}
}
public class MyProgram {
	public static void main(String[] args) {
		char x = 'A';// take just ' '
		System.out.println(x);
		System.out.println(Char.MAX_VALUE);//error cannot be resolved to variable
    }
}
public class MyProgram {
	public static void main(String[] args) {
		boolean x=false;
		System.out.println(x);
		boolean y=true;
		System.out.println(y);
	}
}
public class MyProgram {
	public static void main(String[] args) {
		String x = " Ahmed Abdelmoneim";
		System.out.println(x);
	}  
}
public class MyProgram {
	public static void main(String[] args) {
		byte BtoD = 0b1111111;
		System.out.println(BtoD);

	}

}

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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 #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
}

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 #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 #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;
}

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 #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));
    }
}

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

How to use Alarm Manager in android?

    AlarmManager alarmManager;

> More steps

Application of Kruskal's algorithm in Java

class Main
{
	static int totalWeight = 0;
    // A class to represent a graph edge
    class Edge implements Comparable<Edge>
    {
        int src, dest, weight;
 
        // Comparator function used for sorting edges based on
        // their weight
        public int compareTo(Edge compareEdge)
        {
            return this.weight-compareEdge.weight;
        }
    };
 
    // A class to represent a subset for union-find
    class subset
    {
        int parent, rank;
    };
 
    int V, E;	// V-> no. of vertices & E->no.of edges
    Edge edge[]; // collection of all edges
 
    // Creates a graph with V vertices and E edges
    Main(int v, int e)
    {
        V = v;
        E = e;
        edge = new Edge[E];
        for (int i=0; i<e; ++i)
            edge[i] = new Edge();
    }
 
    // A utility function to find set of an element i
    // (uses path compression technique)
    int find(subset subsets[], int i)
    {
        // find root and make root as parent of i (path compression)
        if (subsets[i].parent != i)
            subsets[i].parent = find(subsets, subsets[i].parent);
 
        return subsets[i].parent;
    }
 
    // A function that does union of two sets of x and y
    // (uses union by rank)
    void Union(subset subsets[], int x, int y)
    {
        int xroot = find(subsets, x);
        int yroot = find(subsets, y);
 
        // Attach smaller rank tree under root of high rank tree
        // (Union by Rank)
        if (subsets[xroot].rank < subsets[yroot].rank)
            subsets[xroot].parent = yroot;
        else if (subsets[xroot].rank > subsets[yroot].rank)
            subsets[yroot].parent = xroot;
 
        // If ranks are same, then make one as root and increment
        // its rank by one
        else
        {
            subsets[yroot].parent = xroot;
            subsets[xroot].rank++;
        }
    }
 
    // The main function to construct MST using Kruskal's algorithm
    void KruskalMST()
    {
        Edge result[] = new Edge[V];  // Tnis will store the resultant MST
        int e = 0;  // An index variable, used for result[]
        int i = 0;  // An index variable, used for sorted edges
        for (i=0; i<V; ++i)
            result[i] = new Edge();
 
        // Step 1:  Sort all the edges in non-decreasing order of their
        // weight.  If we are not allowed to change the given graph, we
        // can create a copy of array of edges
        Arrays.sort(edge);
 
        // Allocate memory for creating V ssubsets
        subset subsets[] = new subset[V];
        for(i=0; i<V; ++i)
            subsets[i]=new subset();
 
        // Create V subsets with single elements
        for (int v = 0; v < V; ++v)
        {
            subsets[v].parent = v;
            subsets[v].rank = 0;
        }
 
        i = 0;  // Index used to pick next edge
 
        // Number of edges to be taken is equal to V-1
        while (e < V - 1)
        {
            // Step 2: Pick the smallest edge. And increment the index
            // for next iteration
            Edge next_edge = new Edge();
            next_edge = edge[i++];
 
            int x = find(subsets, next_edge.src);
            int y = find(subsets, next_edge.dest);
 
            // If including this edge does't cause cycle, include it
            // in result and increment the index of result for next edge
            if (x != y)
            {
                result[e++] = next_edge;
                Union(subsets, x, y);
            }
            // Else discard the next_edge
        }
        int totalMSTWeight = 0;
        


        
        for (i = 0; i < e; ++i) {
        		totalMSTWeight += result[i].weight;
        }
//        System.out.println("total " + totalWeight);
//        System.out.println("MST " + totalMSTWeight);
        System.out.println(totalWeight - totalMSTWeight);
    }
 
    // Driver Program
    public static void main (String[] args) throws Exception
    {
    		BufferedReader br = new BufferedReader (new InputStreamReader(System.in));
    		String in = br.readLine();
    		
    		while (!in.equals("0 0")) {
    			totalWeight = 0;
    			String [] split = in.split(" ");
        		int V = Integer.parseInt(split[0]);
        		int E = Integer.parseInt(split[1]);

            Main graph = new Main(V, E);
            
            for (int i=0; i<E; i++) {
            		in = br.readLine();
            		//System.out.println("split2: " + in);
            		String [] split2 = in.split(" ");
            		int a = Integer.parseInt(split2[0]);
            		int b = Integer.parseInt(split2[1]);
            		int c = Integer.parseInt(split2[2]);
            		
            		graph.edge[i].src = a;
            		graph.edge[i].dest = b;
            		graph.edge[i].weight = c;
            		
            		totalWeight += c;
            		//System.out.println("source: "+a+", dest: " + b + " weight: "+ c);
            }
            graph.KruskalMST();
            in = br.readLine();
    		}
    }
}

#android #java #xml

Android LinearLayout gradient background

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <gradient
        android:angle="45"
        android:startColor="#ff00ff"
        android:endColor="#000000"/>
</shape>

> More steps

Its just print some message on console

for(int i = 0; i < 108; i++) {
System.out.println('Jai Shri Ram!');
}

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