#define using in java/android studio

Question

i am new to stackoverflow and recently interested in android app design. I was a C programmer for mcu coding so not familiar with java syntax.

In C or some compiler i used before, they support a syntax called "#define", which i can put a statement into it like:

#define (tried && sleepy)   BAD_MOOD
#define (happy && joy)      GOOD_MOOD

To be used like:

if (GOOD_MOOD)
  GO_TO_WORK
else if (BAD_MOOD)
  SICKLEAVE
else
  ...

Does java have some syntax like this? or alternatively, should i define many boolean variable instead?

One other thing: if you consider posting here more often, spend some time at the [help]; and learn what / how to ask here ... — GhostCat, Feb 24 '17 at 11:36

GhostCat · Accepted Answer · 2017-02-24T07:42:13.977

Java does not have #define; or any other kind of macro support; as it does not even have the concept of pre processing.

Given your comments: first of all, you really want to step back. You don't learn Java by applying your C knowledge. Period. There is many existing documentation out there that summarizes the important differences between C and Java; you start by searching and reading such stuff.

Then: the real difference is that Java is a (heavily, but not 100%) object oriented programming language; and C is not. So you not only change syntax elements; you apply different concepts. One first starting point here would be the SOLID principles.

And then there are subtle things, such as Java coding style guides - that instruct for simple things as "no _ chars in variable names" (except for SOME_CONSTANT).

And regarding your example, a simple example would look like:

public class Class {
  private final static int MAX_COUNT_OF_STUDENTS = 50;

  private int numberOfStudents;  
  private int numberOfBooks;

  public void setNumberOfStudents(int newCount) {
    numberOfStudents = newCount;
  }

  public boolean isFull() {
    return ( numberOfStudents <= MAX_COUNT_OF_STUDENTS );
  }
  ...

That is how you would approach such things in Java. There key thing is to design classes that represent the objects in the real world you intend to model; to add the required behavior as methods.

And beyond that: even in the C world I would be really really cautious about using #defines this way. Yes, they are convenient and have their place; but using them just to safe typing word like in your example I would consider a bad practice.

so do u think making numbers of boolean variable is a good way? i.e. boolean class_is_full = false; boolean books_are_ready = false; boolean start_the_class = false; if (number_of_students == 50) class_is_full = true; if (number_of_books >= 50) books_are_ready = true; if(class_is_full && books_are_ready) start_the_class = true; basically, i was wanna make my code looks understandable. — Simon, Feb 24 '17 at 06:43
I enhanced my answer; but just for the record: don't come back with more questions. You are at a very basic level; and that requires you doing studying. And this here is not a place were you get teaching for free ;-) — GhostCat, Feb 24 '17 at 07:43
thank you for your time to demonstrate the basic based on my example. I understand some (not all) different between C and java. The SOLID principles sounds reasonable but hard for me to follow. but anyways, that's where I should start with. thanks again. — Simon, Feb 24 '17 at 10:21

#define using in java/android studio

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