if statement not working.Whats wrong with my code?

Question

I'm a beginner with java and I don't know whats wrong with my code. Your assistance will be highly appreciated.

This code should check if any element of the array is less than tc, then its value should be incremented.

int pay1  = 190;
int pay2  = 1175;
int pay3  = 455;
int pay4  = 345;
int tc    = 400;
int[] pay = { pay1, pay2, pay3, pay4 };

for(int i = 0; i < pay.length; i++)
{
    if(pay[i] < tc)
    {
        pay[i] = pay[i]++;
        System.out.println(pay[i]+",");
    }
}

what this code suppose to do, and where is the error or weird behaviour?? — ΦXocę 웃 Пepeúpa ツ, Jun 23 '16 at 18:27
This is not off topic, this is a valid question and shows a thing that should NOT be done in Java. — TofuBeer, Jun 23 '16 at 18:30

TofuBeer · Answer 1 · 2016-06-23T18:45:33.043

7

Change:

pay[i] = pay[i]++;

To:

pay[i]++;

Don't try to modify (++) and assign (=) in the same line or bad things happen. In this case it does the increment, then reassigns the original value.

This code:

int i = 0;
i = i++;

Produces this bytecode (javap -c ):

   0: iconst_0     
   1: istore_1    
   2: iload_1    
   3: iinc 1, 1  
   6: istore_1

Which means:

0: put zero on the stack
1: put the zero into i
2: put the value of i (0) onto the stack
3: increment i by 1 (i now has a value of 1)
6: store the value on the stack (0) into i (i now has a value of 0)

edited Jun 23 '16 at 18:45

answered Jun 23 '16 at 18:30

TofuBeer

60,850
18
118
163

See updated answer @cricket_007 – TofuBeer Jun 23 '16 at 18:43
@cricket_007 _An array access expression refers to a **variable** that is a component of an array._ – Sotirios Delimanolis Jun 23 '16 at 18:45

if statement not working.Whats wrong with my code?

1 Answers1