Question

I am developing a small app while learning Android.

The app is basically making a series of simple math calculations. A button is calling a function where the calculations take place. Everything was working fine, until I inserted an if/else construct.

Inside this construct, I am using variables created before, making calculation and setting other variables with this

if (TS>Ex) {
    Double AE = 0.00;
} else {
    Double AE = (Ex-TS);
};

Double TBTAT = (TS-Ex);
Double Exx = 2864.17;   
if (TBTAT>Exx) {
    Double TAT = (Exx*0.2);
} else {
    Double TAT = (TBTAT*0.2);
};

I have two of these if/else structures.

Then everything is collected and sent to a Text

IT_ResultTXT.setText(Double.toString(AE+TAT+TAF));

In normal conditions, AE, TAT, TAF turn out to “cannot be resolved to a variable” in this last line of the code, but if I declare them at the beginning of the function, I have an error of duplicated variables.

I suppose is a very stupid basic Java programming error, but I cannot find a solution to this.

Answer 1

You have to declare at the beginning (or somewhere else in enclosing scope), only once:

Double AE;

if (TS > Ex) {
    AE = 0.00;
} else {
    AE = (Ex - TS);
};

Double TBTAT = (TS - Ex);
Double Exx = 2864.17;    

Double TAT;

if (TBTAT > Exx) {
    TAT = (Exx * 0.2);
} else {
    TAT = (TBTAT * 0.2);
};