trying to validate negative numbers

Question

I am trying to validate negative numbers but I haven't got clear how to do it, I've tried many steps but it's impossible, I think this the part of the code where I've got to validate because here is where it starts to do the rest, example if after entering name of employee it asks me to enter salary so I've got to avoid negative numbers.

for (int i = 0; i < e; i++) {
    System.out.println("Ingrese el nombre del "+(i+1)+" empleado");
    arr[i][0] = b.readLine();
    for (int j = 1; j < 4; j++) {
        System.out.println("ingrese el "+Concepto(j-1));
        arr[i][j]=String.valueOf(b.readLine());
    }
}

boolean isNegative = (salary <0 ) ? true : false; This is ternary operator; It is short for simple if else block — Shubham Srivastava, Sep 21 '20 at 10:30
@ShubhamSrivastava That would be a weird way to write `boolean isNegative = (salary < 0);` — khelwood, Sep 21 '20 at 10:31
Hello and welcome. Your question is not very clear. Are you perhaps asking how to keep asking for a number when the format is not valid instead of going forward and asking for salary? — Federico klez Culloca, Sep 21 '20 at 10:35
Does this answer your question? [Java - Check if input is a positive integer, negative integer, natural number and so on.](https://stackoverflow.com/questions/19766051/java-check-if-input-is-a-positive-integer-negative-integer-natural-number-an) — flaxel, Sep 21 '20 at 10:37
@FedericoklezCulloca hi thanks, what I want it's to avoid a negative value for example when the programme is executed it asks me for number of employee right? then I enter 4 then it asks me name,salary etc so if by mistake I enter in salary I don't know -100 then I'd like to show message or just an error or the same if I enter -1 as name. cheers — Johan Sebastian Gil Lopez, Sep 21 '20 at 14:52
@JohanSebastianGilLopez take a look [here](https://stackoverflow.com/questions/60698078/how-do-i-make-a-loop-that-commands-the-user-to-keep-inputing-a-value-until-if-co?noredirect=1&lq=1). — Federico klez Culloca, Sep 21 '20 at 15:23

score 0 · Answer 1 · answered Sep 21 '20 at 10:35

0

Negative numbers are always less than 0.

So just add a condition : if ( value > 0 ) -- positive else -- negative

You can also use - For double and float values: Math.signum() and for Integer values: Integer.signum(int i)

answered Sep 21 '20 at 10:35

Prateek Chaudhary

141
10

1

Should the zero also be seen as negative? – flaxel Sep 21 '20 at 10:38
Don't forget zero itself. Strictly speaking, zero is neither negative nor positive, but it is more common to consider zero as positive than as negative. – MC Emperor Sep 21 '20 at 10:39
0 is considered a positive number but logically based on your use case Salary should always be greater than 0 – Prateek Chaudhary Sep 21 '20 at 10:48
@PrateekChaudhary 0 is not a positive number. It's just not a negative number. – khelwood Sep 21 '20 at 13:04

score 0 · Answer 2 · answered Sep 21 '20 at 11:01

0

You can use the Comparision operator. this are the comparision operator in Java:

>(greater than),
<(less than),
== (equal to),
!= (not equal),
>=,
<=

If any number is (> 0) then its positive number and if its (< 0) its negative number.

answered Sep 21 '20 at 11:01

Prem Parmar

1
1

score 0 · Answer 3 · answered Sep 21 '20 at 11:13

0

You can simply use the ternary operator,

int value = value > 0 ? (value : 0);

0 - Some default value if it's a negative

answered Sep 21 '20 at 11:13

Pasindu Wijesinghe

1
1

trying to validate negative numbers

3 Answers3