libGDX: Using preferences for highscore

问题

I know I have asked this question so similar before but I get there no more answer ... I would like, as soon as I lost in my game, my HighScore displayed. Here is the code:

 protected Preferences HighScore () {

    if (score > highscore) { 
        prefs.putInteger("highscore", score); 

        this.highscore = prefs.getInteger("highscore", 0);

        prefs.flush(); 
    }
   return prefs;
}

But if I run my application, only this error is displayed:

Exception in thread "LWJGL Application" java.lang.NullPointerException
at de.firstdemo.game.states.PlayState.HighScore(PlayState.java:641)
at de.firstdemo.game.states.PlayState.render(PlayState.java:601)
at de.firstdemo.game.states.GameStateManager.render(GameStateManager.java:50)
at de.firstdemo.game.RiskyDemo.render(RiskyDemo.java:37)
at com.badlogic.gdx.backends.lwjgl.LwjglApplication.mainLoop(LwjglApplication.java:225)
at com.badlogic.gdx.backends.lwjgl.LwjglApplication$1.run(LwjglApplication.java:126)

I looked in the web but couldn't find any solution...

Thanks for your answers! :)

回答1:

First you get the object:

Preferences preferences = Gdx.app.getPreferences("My preferences");

Then, when you lose in your game, you get the value. I usually check if I lose in the render method with a boolean. In this case you compare your highscore with your current score:

if(IsGameFinished)
{
    int highscore = preferences.getInteger("High score",0);
    if(highscore>=yourCurrentScore)
    {
          // display highscore
    }
    else
    {
          // display yourCurrentScore
         preferences.putInteger("High score", yourCurrentScore);
         preferences.flush();
    }
}

Furthermore in your code there is an error:

protected Preferences HighScore () {

if (score > highscore) { 
    prefs.putInteger("highscore", score); 
    prefs.flush(); // YOU SHOULD FLUSH BEFORE!
    this.highscore = prefs.getInteger("highscore", 0);
}
return prefs;
}

And, why do you return the Preferences? Returning your highscore as an int should be better.

来源：https://stackoverflow.com/questions/46840077/libgdx-using-preferences-for-highscore

标签

java

android

libgdx

sharedpreferences