Question

I am making a program that solves an equation.

I have a variable that changes: i, and a string that is entered: parseLine

What is the easiest way to make:

parseLine = "100 + x"
when i = 1;

into:

"100 + 1"

I tried

String ir = Double.toString(i);
parseLine.replace("x", ir);

but the output is still 100 + x

Answer 1

a String in java is immutable – you can’t change it. The replace method returns a new String instance:

parseLine =  parseLine.replace("x", ir);