Better way to write multiple if statements in java

Question

Hi so lately I've been doing a lot of java programming and I've been using a lot of if statements. the problem is i have to copy and paste the if statements over a hundred times to check all the senarios. Here is an example:

while (i < AreaNumbers.size()) {
        String roomnum = "j" + AreaNumbers.get(i);
        if (roomnum.equals("j100")) {
            if (k == 1) {
                j100.setVisible(true);
                j100.setToolTipText("<html>" + "<br>" + "Room Number: " + AreaNumbers.get(i) + "<br>" + "Incident ID: " + IncidentID.get(i) + "<br>" + " Teacher: " + Teachers.get(i) + "<br>" + " Description: " + Descriptions.get(i) + "</html>");
                k = k + 1;
            } else if (k > 0) {
                j100.setToolTipText(k + " help desk calls, click here for more information");
                k = k + 1;
            }

for this example i would copy and paste the if (roomnum.equals("j100")) { and everything past it for every label i want to check and compare. Is there anyway i could do this where i could write a statement that goes through this same scenario once and everywhere it sees j100 it could replace it after each time with a different label, such as j101 j107 an so on. Im sorry if this isnt very clear i just cant think of a better way to word it. Thanks in advance.

You have a variable named j100 and, according to your description, this code will be repeated over a hundred times. Does it mean you plan on having hundred variables like that? — Nikita Rybak
– Nikita Rybak, Commented Jan 25, 2011 at 0:01

Oliver Charlesworth · Accepted Answer · 2011-01-25 00:10:22Z

9

Don't use numbered variable names (like j100, j101, etc.). Use an array instead, so you can loop over them programatically:

SomeType[] j = new SomeType[1000];

for (int z = 0; z < j.length; z++) {
    j[z] = new SomeType();

    j[z].setTooltipText("Hello world");
}

Depending on what you need to do, you may want to investigate the more advanced collections classes instead of simple arrays.

edited Jan 25, 2011 at 0:10

answered Jan 25, 2011 at 0:02

Oliver Charlesworth

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1 Comment

KitsuneYMG Over a year ago

I hope you never get to room -1

KitsuneYMG · Accepted Answer · 2011-01-25 00:02:05Z

0

you could use a Map<String, Runnable> using the label as the key and to a Runnable. Depending on how you write you Runnable subclasses, this could alleviate a lot of redundancy.

if( myMap.containsKey( myLabel ) ) {
  myMap.get(myLabel).run();
}

answered Jan 25, 2011 at 0:02

KitsuneYMG

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6 Comments

nrobey Over a year ago

I believe this approach is a bit too advanced for the question.

KitsuneYMG Over a year ago

What do Runnables have to do with Threads besides the fact that a Thread can take a Runnable in the ctor? A Runnable is just an interface with a run method. Unlike c++ java does not have operator() for I used Runnable. This is the closest I can get to a functor in java6. You could use Callable or even create your own interface if you don't like Runnable.

Oliver Charlesworth Over a year ago

As far as I understand it, the Runnable interface is designed for actions to be executed by a thread (it even says so in the documentation). It seems a bit perverse to implement this interface just to get a run() method, which you could quite easily do with a custom interface (that doesn't lead to confusion about threads!).

KitsuneYMG Over a year ago

Why introduce a new interface that will almost certainly be exactly the same as Runnable? Runnable is the closest thing java currently has to a no-return lambda/functor. The interface Runnable has nothing intrinsically tying it to Thread.

nrobey Over a year ago

You could also create your own interface with a go() or do() or execute() method. This way, you would not confuse those who are used to seeing Runnable in threading environments.

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