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Compare these two implementations. When having a create() method that the class that extends BaseScreen also calls I get a null pointer exception bc of Stage, why?




package com.mygame.ui.screens;

import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.Input;
import com.badlogic.gdx.Screen;
import com.badlogic.gdx.graphics.Color;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.OrthographicCamera;
import com.badlogic.gdx.scenes.scene2d.Stage;
import com.badlogic.gdx.scenes.scene2d.ui.Button;
import com.badlogic.gdx.scenes.scene2d.ui.TextButton;
import com.badlogic.gdx.utils.viewport.FitViewport;


public class BaseScreen implements Screen
{
    protected Stage stage;
    protected MyGame myGame;

    public BaseScreen()
    {

    }

    public BaseScreen(MyGame myGame)
    {
        this.myGame = myGame;

        stage = new Stage();
        create();
    }

    public void create()
    {
        // do stuff ...
    }

    @Override
    public void render (float delta)
    {
        if (Gdx.input.isKeyJustPressed(Input.Keys.BACK))
        {
            Gdx.app.exit();
        }

        Gdx.gl.glClearColor(0, 0, 0, 1);
        Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

        stage.act(delta);
        stage.draw();
    }

    @Override
    public void resize (int width, int height)
    {
        stage.getViewport().update(width, height, true);
    }

    @Override
    public void dispose () {
        stage.dispose();
    }

    @Override
    public void show() {
        Gdx.input.setCatchBackKey(true);
    }

    @Override
    public void hide() {
        /* Don't need to do anything here. */
    }

    @Override
    public void pause() {
        /* Don't need to do anything here. */
    }

    @Override
    public void resume() {
       /* Don't need to do anything here. */
    }
}





versus



package com.mygame.ui.screens;

import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.Input;
import com.badlogic.gdx.Screen;
import com.badlogic.gdx.graphics.Color;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.OrthographicCamera;
import com.badlogic.gdx.scenes.scene2d.Stage;
import com.badlogic.gdx.scenes.scene2d.ui.Button;
import com.badlogic.gdx.scenes.scene2d.ui.TextButton;
import com.badlogic.gdx.utils.viewport.FitViewport;


public class BaseScreen implements Screen
{
    protected Stage stage;
    protected MyGame myGame;

    public BaseScreen()
    {

    }

    public BaseScreen(MyGame myGame)
    {
        this.myGame = myGame;

        stage = new Stage();
    }

    @Override
    public void render (float delta)
    {
        if (Gdx.input.isKeyJustPressed(Input.Keys.BACK))
        {
            Gdx.app.exit();
        }

        Gdx.gl.glClearColor(0, 0, 0, 1);
        Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

        stage.act(delta);
        stage.draw();
    }

    @Override
    public void resize (int width, int height)
    {
        stage.getViewport().update(width, height, true);
    }

    @Override
    public void dispose () {
        stage.dispose();
    }

    @Override
    public void show() {
        Gdx.input.setCatchBackKey(true);
    }

    @Override
    public void hide() {
        /* Don't need to do anything here. */
    }

    @Override
    public void pause() {
        /* Don't need to do anything here. */
    }

    @Override
    public void resume() {
       /* Don't need to do anything here. */
    }
}