unlocking levels in Android Game logic

Question

I have a level scene that i allow the user to select a level.

But to move on to the next level the user must complete the level before it.

Right now the first level which is automatically unlocked.

When it is completed i want unlock the second level. and when the second level is completed, unlock the third level.

i cant think of how i would go about doing this. i thought of sharedpreferences but dont know the logic i should use for this.

i could use some help on the logic behind this.

Any can help me out?

EDIT:

In my gameplay scene when is game is completed i call this to sharedpreference

editor.putString("level_completed"+level, "unlocked");
editor.commit();

Then i do..

String levelStatus = preference.getString("level_completed:"+level, "locked");

if(levelStatus.equals("unlocked")){

}else{
    if(level == 0){
        box.setUserData("unlocked");
}else{
        box.setColor(1.0f,0.0f,0.0f);
        box.setUserData("locked");
    }
}

in the level selection scene to check if the level is unlocked.

This doesnt seem to be working to well. A level that should be unlocked isnt unlocked.

You could have an int which represents how far down you are in the story. It would store how many levels you have completed and thus you would know what to unlock. — Ryan Amos, Mar 09 '12 at 02:25
In your code addition, one preference has a colon and the other does not. — Julian Fondren, Mar 09 '12 at 02:48
thanks for pointing this out!! i think this fixed me issue! I guess im over whelmed. lol — coder_For_Life22, Mar 09 '12 at 03:08

score 3 · Accepted Answer · answered Mar 09 '12 at 02:25

There are a number of ways you could approach it. If the progression is always linear (1, 2, 3, 4) then you could just store an integer for "max unlocked level" and then update it whenever you complete a level. Otherwise, you could also have many booleans like "level 2 unlocked" and when you complete level 1, you can set "level 2 unlocked" to true. Shared Preferences is definitely a reasonable way to go.

score 2 · Answer 2 · answered Mar 09 '12 at 02:29

What i would do is look at it in an Object Oriented Perspective, which is what Java is all about. When i get stuck on a piece of code then i write it down. Think of what the objective of the code is.

You probably have a class called Level. In this level class you could have a property called "unlocked" or the opposite "locked". Then when the user goes to your "play a level" screen or what have you, then only allow the user to see the levels that are unlocked.
You also probably have a Player class of some sort so you could have a property called "unlockedLevels" which is of the type Level[]. So then all of the unlocked levels would be in this array of Levels.

It is all about how your code is structured, structure and true Object Orientation are the most important things in Java. When you stray from Object Oriented Design then you can run into problems that should never have existed.

Good suggestion! You are right! Right now when a user finishes a level, i save it in shared preference. When the user is on the level selection screen i test to see which levels are completed or unlocked. For some reason this method isnt working to well for me. i can edit my answer if needed. — coder_For_Life22, Mar 09 '12 at 02:36
Yes please do, If you could list your class structure (relevant pieces) and tell me what each part does in your program, ill suggest what i would do — John, Mar 09 '12 at 02:41

score 2 · Answer 3 · answered Mar 09 '12 at 02:36

At some point, unless your game restarts from the beginning every time the user does something else for a bit, you save the state of the game. You save the user's score, the state of the game, etc. When you do this, however you do this, save also the unlocked levels. It's only one bit of information per level, so you don't need to be clever about this. Perhaps you also have a 'save' button, save files, the ability to load from a save. Again, just throw the user's level unlocks in when you're saving everything else.

Or have you not begun to save anything, yet?

Well, start by saving state in the bundles given to activity lifecycle methods, like onPause. If multiple saves are appropriate for your game, go with files and decide on their structure. If only one 'save' will do, preferences are likely to work just fine for you. A test for that: if you ever want to calculate the key of a preference, don't use preferences.

Thanks for the response! Check out my update to see where i am. i am using preference as we speak, — coder_For_Life22, Mar 09 '12 at 02:43

unlocking levels in Android Game logic

3 Answers3