Question

Is the following code clear and easy to read?

public void createDatabase() throws SQLException, IOException {
    SQLiteDatabase database = dbStore.getDatabase();
    LineNumberReader scriptInputReader = new LineNumberReader(new InputStreamReader(getClass().getResourceAsStream(SCRIPT_CREATE)));
    for(String line; (line = scriptInputReader.readLine()) != null;) {
        database.execSQL(line);
    }
}

I write a lot of “for” loops like the one above. For me it looks clear – it shows the temporary variable (“line”) used in the loop, limits it’s scope and points out when the loop ends (when “readLine” returns “null”). I wonder if other programmers will hate me for those…

or this one:

    SQLiteDatabase database = dbStore.getDatabase();
    Cursor cursor = database.query("PINS", new String [] {"ID", "X", "Y"}, null, null, null, null, "ID");
    if(cursor.moveToFirst()) {
        for(; !cursor.isAfterLast(); cursor.moveToNext()) {
            (...)
        }
    }
    cursor.close();

Are things like the above just “neat” or already a Java-puzzles?

Answer 1

I like what you’ve done, but I would make one small change:

for(String line = scriptInputReader.readLine(); line != null; line = scriptInputReader.readLine()) {
    database.execSQL(line);
}

This separates the iteration action from the loop termination condition. Also, unlike the “while” version, it limits the scope of the line variable to the loop – narrowing scope as much as possible is good coding practice.

Also, code style checkers usually consider assignments nested within tests as “poor style”. To be clear, your code is a bit like this:

for (int i = -1; ++i < max;) { // don't do this: increment action inside condition section
    // some code
}