Java: How to assign variable value in a loop?

Question

I have created timeslots for patient scheduling. I have made 160 of them for one week but I want thousand weeks, so for every timeslot I have made a variable week (int). Now for some reason, every timeslot gets the value 1000 for the variable week. If I test the same code on a test variable it works just fine. Anyone has an idea?

    int[] test = new int[160000];
    for(int j =0;j<1000;j++)
    {
      for(int i = 0;i < 160;i++)
     {
         timeslot[j*160 + i] = timeslot_build[i];
         timeslot[j*160 + i].set_week(j+1);
         test[j*160 + i] = (j+1);

     }      

    }


     System.out.println(test[150]);
     System.out.println(test[5166]);
     System.out.println(test[44000]);
     System.out.println(test[100000]); 

     System.out.println(timeslot[150].week);
     System.out.println(timeslot[5166].week);
     System.out.println(timeslot[44000].week);
     System.out.println(timeslot[100000].week);

This is the output:

1 33 276 626 1000 1000 1000 1000

Could you provide timeslot, or check that timeslot.set_week does set the week field properly ? — Sxilderik
– Sxilderik, Commented Apr 26, 2019 at 10:06
What is timeslot_build? Why do you assign twice the week value to timeslot(.set_week and .week)? — NeplatnyUdaj
– NeplatnyUdaj, Commented Apr 26, 2019 at 10:07
Assigning this value twice is a mistake but it shouldn't matter. — Thy
– Thy, Commented Apr 26, 2019 at 10:16

talex · Accepted Answer · 2019-04-26 10:44:19Z

2

When you assign timeslot[j*160 + i] = timeslot_build[i] you use same instance.

So timeslot[0*160 + i] = timeslot[1*160 + i] = timeslot[2*160 + i] etc.

You have to create new instance every time. Because now you have only 160 of whatever type timeslot have and timeslot array store references for them.

edited Apr 26, 2019 at 10:44

answered Apr 26, 2019 at 10:25

talex

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5 Comments

Thy Over a year ago

I'm sorry, can you clarify that. This is how I initialized timeslots: Timeslot[] timeslot = new Timeslot[160000];

talex Over a year ago

How you initialize timeslot_build?

Thy Over a year ago

Ah, I understand what you mean but that's actually what I want. I want timeslot[0*160 + i] = timeslot[1*160 + i] = timeslot[2*160 + i], only the weeks should differ.

talex Over a year ago

You can't have one instance have different values in it field.

talex Over a year ago

timeslot[0*160 + i] = timeslot[1*160 + i] mean they refer to single instance.

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