Question

In the expression of a while loop, is it possible to initialise a variable, then use that as part of the expression?

It’s probably simpler in code:

while (int a = someMethod(), a<b)

It would be possible to just add another method, and so have to following:

private boolean whileLoopTest() {
    int a = someMethod();
    return a<b;
}

public void originalMethod() {
    while (whileLoopTest()) {
        //...

but this doesn’t seem as neat.

EDIT
I also don’t want to directly compare the method to my variable, as it is compared to several variable, and so if would be a long, unreadable mess. A better example of what I want would be:

while (int a = SomeClass.someStaticMethod(), -1<a && a<b)

It’s not true in my case, but this would be a equally valid question if someStaticMethod() took a long time to return – I would only want to call it once.
I’m fairly new to StackOverflow, so I’m not sure if giving other situations where this would apply is what I should be doing.

Answer 1

int a;
while((a = someMethod()) < b){
    //do something
}

A common use for this is reading from a file:

BufferedReader fileIn = ...
String line;
while((line = fileIn.readLine()) != null){
    //do something
}
fileIn.close();

/edit
You can do this for your new scenario:

int a;
while(-1 < (a = SomeClass.staticMethod()) && a < b) {
    //do something
}

Once the left hand portion of the && statement is executed, the return value of SomeClass.staticMethod() is stored in a, which carries over the the right hand portion of the statement.