Java Programming Examples

Compile and Execute Java Online

java

import java.util.Scanner;

public class HelloWorld {
	Scanner input = new Scanner(System.in);

	public static void main(String[] args) {
		new HelloWorld();
	}

	// This will act as our program switchboard
	public HelloWorld() {
		String[] cargohold = new String[10];

		System.out.println("Welcome to the BlackStar Cargo Hold interface.");
		System.out.println("Please select a number from the options below");
		System.out.println("");

		while (true) {
			// Give the user a list of their options
			System.out.println("1: Add an item to the cargo hold.");
			System.out.println("2: Remove an item from the cargo hold.");
			System.out.println("3: Sort the contents of the cargo hold.");
			System.out.println("4: Search for an item.");
			System.out.println("5: Display the items in the cargo hold.");
			System.out.println("0: Exit the BlackStar Cargo Hold interface.");

			// Get the user input
			int userChoice = input.nextInt();
			input.nextLine();

			switch (userChoice) {
			case 1:
				addItem(cargohold);
				break;
			case 2:
				removeItem(cargohold);
				break;
			case 3:
				sortItems(cargohold);
				break;
			case 4:
				searchItems(cargohold);
				break;
			case 5:
				displayItems(cargohold);
				break;
			case 0:
				System.out.println("Thank you for using the BlackStar Cargo Hold interface. See you again soon!");
				System.exit(0);
			}
		}

	}

	private void addItem(String cargohold[]) {
		String additem= input.next();
		for(int i=0; i< cargohold.length;i++){
		    if(cargohold[i]==null){
		        cargohold[i]=additem;
		        i=cargohold.length;
		    }
		    if(i==cargohold.length-1 && cargohold[cargohold.length-1]!=additem){
		      System.out.println("Sorry your inventory is full.");  
		    }
		}
		System.out.println("You have added "+additem);

	}

	private void removeItem(String cargohold[]) {
		System.out.println("Specify the item you want to remove.");
		String removeitem= input.next();
		for(int i=cargohold.length-1;i>-1;i--){
		   if(cargohold[i]==removeitem){
		       cargohold[i]=null;
		       i=0;
		   } 
		   if(i==0 && cargohold[0]!= removeitem){
		       System.out.println("That Item couldn't be found in your inventory.");
		   }
		}
		

	}

	private void sortItems(String cargohold[]) {
      if(cargohold[0] !=)
        for(int i=1; i<cargohold.length; i++){
            int key= cargohold[i];
            int j= i-1;
            while(j>=0 & cargohold[j].compareTo(key)>=0){
                cargohold[j+1]=cargohold[j];
                j=j-1;
            }
            cargohold[j+1]=key;
        }
        System.out.println("List has been sorted.");
        System.out.println("Would you like to view the sorted list?: 1: Yes 2: No");
        int answer=input.nextInt();
        if(answer==1){
         for(int i=0; i< cargohold.length; i++){
             System.out.println(i+" | "+cargohold[i]);
             if(cargohold[i+1]==null){
                 i=cargohold.length;
             }
         }   
        }

	}

	private void searchItems(String cargohold[]) {
		System.out.println("What item do you want to find?");
		String item= input.next();
		int Point=0;
		int[] itemlocations=int[cargohold.lenght];
		
		for(int i=0; i<cargohold.length;i++){
		    if(cargohold[i]==item){
		       itemlocations[Point]=i;
		       Point=i+1;
		    }
		}
		if(Point==0){
		System.out.println("Couldn't find the item.");
		}
		else{
		    System.out.println("We have found "+item+" at: ")
		    for(int k=0; k<itemlocations.length; k++){
		       System.out.print(itemlocations[k]+",");
		       if(itemlocations[k+1]==null){
		           k=itemlocations.length;
		       }
		        
		    }
		    System.out.print(" positions in your inventory.");
		}
	}

	private void displayItems(String cargohold[]) {
        int[] counter=int[cargohold.length];
        String[] uniqueItems= String[cargohold.length];
        int firstnull=0;
        for(int i=0; i<cargohold.length;i++){
            if(i=0){
                uniqueItems[0]=cargohold[0];
                counter[0]++;
                firstnull=1;
            }
            else{
                for(int j=0; j<i; j++){
                    if(uniqueItems[j]=cargohold[i]){
                        counter[j]++;
                    }
                    else{
                        uniqueItems[firstnull]=cargohold[i];
                        counter[firstnull]++;
                        firstnull++;
                    }
                }
            }
        }
        System.out.println("You have: ");
        for(int i=0; i<uniqueItems.length; i++){
            System.out.println(uniqueItems[i]+" - "+counter[i]);
        }
        System.out.println("In your inventory");
	}
}

Compile and Execute Java Online

java

public class HelloWorld{

     public static void main(String []args){
        System.out.println( "Hello World.");
          
     }
}

Compile and Execute Java Online

java

public class HelloWorld{

     public static void main(String []args){
        System.out.println("Hello World");
     }
}

Compile and Execute Java Online

java

import java.io.*;
import java.util.*;
public class HelloWorld{

     public static void main(String []args)throws IOException
     {
        Scanner sc = new Scanner(new File("test.txt"));
        String str="";
        while(sc.hasNext())
        {
            String s = sc.next();
            str+=s;
            str+=" ";
        }
        HashMap<String, Integer> map = new HashMap<>();
        String sentence = str.toLowerCase();

        for(String word : sentence.split("\\W")) 
        {
            if(word.isEmpty()) 
                continue;
            
            if(map.containsKey(word)) 
                map.put(word, map.get(word)+1);
            
            else 
                map.put(word, 1);
            
        }

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

public class HelloWorldpublic class HelloWorld

java

public class HelloWorld{

     public static void main(String []args){
        System.out.println("Hello World");
     }
}

Compile and Execute Java Online

java

public class HelloWord {
   int puppyAge;

   public HelloWord(String name) {
      // This constructor has one parameter, name.
      System.out.println("Name chosen is :" + name );
   }

   public void setAge( int age ) {
      puppyAge = age;
   }

   public int getAge( ) {
      System.out.println("Puppy's age is :" + puppyAge );
      return puppyAge;
   }

   public static void main(String []args) {
      /* Object creation */
      HelloWord myPuppy = new Puppy( "tommy" );

      /* Call class method to set puppy's age */
      myPuppy.setAge( 2 );

      /* Call another class method to get puppy's age */
      myPuppy.getAge( );

      /* You can access instance variable as follows as well */
      System.out.println("Variable Value :" + myPuppy.puppyAge );
   }
}

CtCI

java

import java.util.*;

public class Question4_3 {

    static class Node {
        Integer data;
        Node left;
        Node right;

        public Node(Integer data) {
            this.data = data;
        }

        public int height() {
            int leftHeight = left != null ? left.height() : 0;
            int rightHeight = right != null ? right.height() : 0;
            return 1 + Math.max(leftHeight, rightHeight);
        }

        public boolean isBalanced() {
            int leftHeight = left != null ? left.height() : 0;
            int rightHeight = right != null ? right.height() : 0;
            return (Math.abs(leftHeight - rightHeight) <= 1);
        }
    }

    public static Node minimalBST(int[] sorted) {
        return minimalBST(sorted, 0, sorted.length - 1);
    }

    private static Node minimalBST(int[] sorted, int start, int end) {

        if (start > end) {
            return null;
        }

        int mid = (start + end) / 2;
        
        Node node = new Node(sorted[mid]);

        node.left = minimalBST(sorted, start, mid - 1);
        node.right = minimalBST(sorted, mid + 1, end);

        return node;
    }

    public static Node insert(Node node, Integer data) {
        if (data == null) {
            return null;
        }

        if (node == null) {
            node = new Node(data);
            return node;
        }

        if (data.compareTo(node.data) <= 0) {
            if (node.left == null) {
                node.left = new Node(data);
            } else {
                insert(node.left, data);
            }
        } else {
            if (node.right == null) {
                node.right = new Node(data);
            } else {
                insert(node.right, data);
            }
        }

        return node;
    }

    public static void main(String[] args) {
        int[] array = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

        Node root = minimalBST(array);

        System.out.println("Root? " + root.data);
        // System.out.println("Created BST? " + root.isBST());
        System.out.println("Height: " + root.height());
        System.out.println("Is balanced? " + root.isBalanced());

        Random random = new Random();

        root = null;
        array = new int[20];

        for (int i = 0; i < array.length; i++)
        {
            array[i] = random.nextInt(array.length);
            root = insert(root, array[i]);
            System.out.print(array[i] + " ");
        }
        System.out.println();

        // root = minimalBST(array);

        System.out.println("Root? " + root.data);
        System.out.println("Height: " + root.height());
        System.out.println("Is balanced? " + root.isBalanced());
    }
}

Compile and Execute Java Online

java

public class HelloWorld {
    
    int age;

     public void pup(int age){
         
         age = age + 1;

         System.out.println("My pup's age is: "+ age);
         
     }
     

     public static void main(String []args){

      HelloWorld doggy = new HelloWorld();
      
      doggy.pup(1);
      

     }
}

teste

java

//Caixa.java:
public class Caixa {

//Variaveis de classe
//O volume total e compartilhado:
public static double volumeTotal = 0;

//Atributos especificos:
private double altura;
private double comprimento;
private double largura;

//Construtor:
public Caixa(double a, double b, double c) {
altura = a;
comprimento = b;
largura = b;
volumeTotal = volumeTotal+(altura*comprimento*largura);
}

//Metodo calcular volume:
public double volume() {
    return altura*comprimento*largura;
}
}

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