help please

[Bob Matthews]

I have the following code:-

if (curr_trade_dir == "Up") {
    if (myCurrPositionValue == 0.2){
        message_code = 2;
    } else {
    if (myCurrPositionValue == 0.1){
        message_code = 1;
        }
    }
}


if (curr_trade_dir == "Down") {
    if (myCurrPositionValue == 0.2){
        message_code = -2;
    } else {
    if (myCurrPositionValue == 0.1){
        message_code = -1;
        }
    }
}

if (myCurrPositionValue == 0){
        message_code = 0;
}    

String message_string = Integer.toString(message_code);

When I run this part of code, I always end up with the 'zero' message_string
I have tried checking the abs value of (myCurrPositionValue - 0.2) say being less the 0.001 but the same result occurs

What am I doing wrong?

Bob M

[Paweł Baczyński]

Do not compare Strings with == operator.
Use equals() method instead.

AvoidTheEqualityOperator (this is a link).

Also, instead of

if (condition){
    // code
} else {
    if (anotherCondition){
        // another code
    }
}

you can (and should) write

if (condition) {
    // code
} else if (anotherCondition) {
   // another code
}

Also, by convention, you should use camelCaseVariableNames instead of underscored_variable_names.

[Stephan van Hulst]

You're testing curr_trade_dir for identity, not equality. When you write curr_trade_dir == "Down", you're testing whether they are exactly the same two objects in memory, not whether they mean the same thing. The lesson is simple: Don't use == where you should use equals().

Another thing, doubles can not represent certain values exactly. Doing comparisons like myCurrPositionValue == 0.2 is asking for trouble. If you really must use floating point arithmetic, you need to introduce a tolerance when you want to compare two values.

Finally, don't use variable names such as curr_trade_dir. Use currentTradeDirection. Strings are also a poor substitute for expressive data types. Use an enum for your directions:

if (currentTradeDirection.equals(Direction.UP)) {

[Stephan van Hulst]

Paweł is much quicker than I am today.

[Paweł Baczyński]

Also, please UseAMeaningfulSubjectLine (this is also a link).

[Bob Matthews]

Thank you

Bob M