CODEWITHSUNDEEP
javaclassobject
Kryštof Hanžl
Kryštof Hanžl

Reputation: 27

Java -random select obejct

i have this two codes:

game.java

package game;

import java.util.*;

public class games {
    public static Random rd = new Random();
    

    public static void main(String[] args){
        
    //enemies
    enemy skeleton = new enemy(1, "jarda" , 2 , 3);
    enemy kostlivec = new enemy(2, "pepa" , 2 , 3);
     
    }
}

and enemy.java

package game;

import java.util.jar.Attributes.Name;

public class enemy {
    public static int number;
    public static String název;
    public static int damage;
    public static int health;

    public enemy(int number, String název, int damage, int health){
        this.number = number;
        this.název = název;
        this.damage = damage;
        this.health = health;
    }


    
}

How can i randomly select one of these objects and print it to user ? I try arraylist, arrays and many others.

Upvotes: 0

Views: 68

Answers (3)

Rohan Kumar
Rohan Kumar

Reputation: 5882

As pointed out in comments, you should use random.nextInt() with upper bound. You can create a List<Enemy> and pass pass it's size() as upperbound. Here is a simple implementation:

private static Enemy getRandomEnemy(final List<Enemy> enemies) {
    int randomEnemyIndex = rd.nextInt(enemies.size());
    return  enemies.get(randomEnemyIndex);
}

You would call it from main() method like this:

ArrayList<Enemy> enemies = new ArrayList<>();
// enemies
enemies.add(new Enemy(1, "jarda" , 2 , 3));
enemies.add(new Enemy(2, "pepa" , 2 , 3));
enemies.add(new Enemy(3, "Palpatine" , 10 , 3));
enemies.add(new Enemy(4, "Darth Vader" , 9 , 10));

System.out.println("Current Enemy: " + getRandomEnemy(enemies).název);
System.out.println("Current Enemy: " + getRandomEnemy(enemies).název);
System.out.println("Current Enemy: " + getRandomEnemy(enemies).název);
System.out.println("Current Enemy: " + getRandomEnemy(enemies).název);

Bdw, Some nitpicks for Enemy class; By convention Java class names should start with an uppercase character. I think it should have non static field members. Otherwise, I don't see any point in storing different enemies:

public class Enemy {
    public int number;
    public String název;
    public int damage;
    public int health;

    public Enemy(int number, String název, int damage, int health){
        this.number = number;
        this.název = název;
        this.damage = damage;
        this.health = health;
    }
}

Upvotes: 1

maloomeister
maloomeister

Reputation: 2486

As described in the comment:

public class Testing {

    public static void main(String[] args) {

        MyObject obj1 = new MyObject(1, 2);
        MyObject obj2 = new MyObject(3, 4);
        ArrayList<MyObject> myList = new ArrayList<>();
        myList.add(obj1);
        myList.add(obj2);
        
        Random rand = new Random();
        int randResult = rand.nextInt(myList.size());
        System.out.println(myList.get(randResult));
    }
}

class MyObject {
    private int value;
    private int anotherValue;
    
    MyObject(int v1, int v2) {
        value = v1;
        anotherValue = v2;
    }
    
    @Override
    public String toString() {
        return "MyObject with values: " + value + ", " + anotherValue;
    }
}

Output:

MyObject with values: 1, 2

Upvotes: 0

Thuan Tran
Thuan Tran

Reputation: 437

Add Object into a List, and get Index Random by Random.nextInt(list.size()) Code

package com.game.main;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

import com.game.model.Enemy;

public class Games {

    public static void main(String[] args) {
        Enemy skeleton = new Enemy(1, "jarda", 2, 3);
        Enemy kostlivec = new Enemy(2, "pepa", 2, 3);

        List<Enemy> list = new ArrayList<>();
        list.add(skeleton);
        list.add(kostlivec);

        Random random = new Random();
        int indexRandom = random.nextInt(list.size());
        System.out.println(list.get(indexRandom));
    }
}

Upvotes: 1

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