How to run multiple FOR at the same time

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In the code below I have 4 for and they run in sequence, but I need them to run them all at the same time.

public class main 
{
public static void main(String[] args)
{
    long init  = System.currentTimeMillis(); 
    ataque(999999, 999999);
    long end  = System.currentTimeMillis(); 
    long diff = end - init;
    System.out.print("Demorou " + (diff / 1000) + " segundos");
}
public static void ataque(int limite, int busca)
{
    int for1 = 0;
    int for2 = limite / 4;
    int for3 = for2 + for2;
    int for4 = for2 = for3;

    for(int i = for1; i < for2; i++)
    {
        /*if(i == busca)
        {
            break;
        }*/

        System.out.println(i + " de " + busca + "\r"); 
    }
    for(int i = for2; i < for3; i++)
    {
        /*if(i == busca)
        {
            break;
        }*/

        System.out.println(i + " de " + busca + "\r"); 
    }
    for(int i = for3; i < for4; i++)
    {
        /*if(i == busca)
        {
            break;
        }*/

        System.out.println(i + " de " + busca + "\r"); 
    }
    for(int i = for4; i < limite; i++)
    {
        /*if(i == busca)
        {
            break;
        }*/

        System.out.println(i + " de " + busca + "\r"); 
    }
}
}
java for
  • 2

    You’ll have to use Threads, follow a link to give you a notion: link

  • 1

    Why do you need them at the same time? I think your problem is something else.

  • 1

    Does it have to be really at the same time? With exact accuracy? Or just finish and start at the same time? These details can make the difference when telling you how to solve your problem.

  • Good evening, I wonder if the answer helped you, if not please comment on what you think is missing.

1 answer

2

You can create 4 Threads with Runnable. Note that nay will be exactly at the same time, but one need not wait for the other, example:

new Thread(new Runnable(){
    @Override
    public void run() {
        for(int i = for1; i < for2; i++)
        {
            System.out.println(i + " de " + busca + "\r"); 
        }
    }
}).start();

new Thread(new Runnable(){
    @Override
    public void run() {
        for(int i = for2; i < for3; i++)
        {
            System.out.println(i + " de " + busca + "\r"); 
        }
    }
}).start();

However if you really need them to be at the same time, you will have to create all events within a single loop and use a boolean variable to check if at least one of the conditions has entered aIF:

bool testIfs = false;
int increment1 = 0;
int increment2 = 0;

while (true) {
    if (increment1 < for2) {
        //Se entrar na condição então não irá lançar o break
        testIfs = true;

        System.out.println(increment1 + " de " + busca + "\r"); 

        increment1++;
    }

    if (increment2 < for3) {
        //Se entrar na condição então não irá lançar o break
        testIfs = true;

        System.out.println(increment2 + " de " + busca + "\r"); 

        increment2++;
    }

    if (testIfs == false) {
       //Se o loop não entrou em nenhuma das if então é executado o break pra poder parar o loop
       break;
    }

    //Se não houve break então testIfs volta a ser false pra testar novamente o loop
    testIfs = false;
}

In this example, I just added a two conditions to understand, but one can add several "ifs".

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