//Map defines a generic interface for an object that holds key-value pairs as elements. The key is used to retrieve (like the index in an array or List) some value. A key must be unique and map to exactly one value.
//The HashMap defines no specific ordering for the keys and is the most optimized implementation for retrieving values.
//The LinkedHashMap keeps the keys in insertion order and is slightly less optimal than the HashMap.
//The TreeMap keeps keys in their natural order (or some custom order defined using a Comparator). This implementation has a significant performance decrease compared to HashMap and LinkedHashMap but is great when needing to keep keys sorted.
//A Map has the following methods for accessing its elements:
//put(): Sets the value that key maps to. Note that this method replaces the value key mapped to if the key was already present in the Map.
//get(): Gets, but does not remove, the value the provided key argument points to if it exists. This method returns null if the key is not in the Map.
Map<String, String> myMap = new HashMap<>();
myMap.put("Hello", "World") // { "Hello" -> "World" }
myMap.put("Name", "John") // { "Hello" -> "World" }, { "Name" -> "John" }
String result = myMap.get("Hello") // returns "World"
String noResult = myMap.get("Jack") // return `null`
// Given a map, `myMap`, with the following key-value pairs { "Hello" -> "World" }, { "Name" -> "John"}
for (Map.Entry<String, String> pair: myMap.entrySet()){
System.out.println("key: "+pair.getKey()+", value: "+pair.getValue());
}
// OUTPUT TERMINAL:
// key: Name, value: John
// key: Hello, value: World
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
}
}
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
}
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;
}
}
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));
}
}
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];
}
}
}
// 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);
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();
}
}
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