stage.act（）上的NullPointerException(NullPointerException on stage.act())
当我运行游戏并点击屏幕退出我的启动画面时，它应该将我带到我的MainMenu，但它只是冻结。 我找到了错误告诉我的代码行，但没有帮助。（MainMenu.java:124）该行只显示了stage.act（）; 比stage.draw（）; 如果我试图删除或注释掉stage.act（）;.（MyGdxGame.java:31）然后指向我的super.render（）;. 我不知道什么是错的，任何帮助都会很棒。
错误：
Exception in thread "LWJGL Application" java.lang.NullPointerException at com.jack.mygdxgame.screens.MainMenu.render(MainMenu.java:124) at com.badlogic.gdx.Game.render(Game.java:46) at com.jack.mygdxgame.MyGdxGame.render(MyGdxGame.java:31) at com.badlogic.gdx.backends.lwjgl.LwjglApplication.mainLoop(LwjglApplication.java:225) at com.badlogic.gdx.backends.lwjgl.LwjglApplication$1.run(LwjglApplication.java:126)MyGdxGame代码：
package com.jack.mygdxgame; import com.badlogic.gdx.Game; import com.badlogic.gdx.Gdx; import com.badlogic.gdx.Screen; import com.badlogic.gdx.graphics.Texture; import com.badlogic.gdx.graphics.g2d.SpriteBatch; import com.jack.mygdxgame.screens.GameScreen; import com.jack.mygdxgame.splash.SplashScreen; public class MyGdxGame extends Game { public static int nWidth; public static int nHeight; private Game game; public MyGdxGame() { game = this; } @Override public void create() { nWidth = Gdx.graphics.getWidth(); nHeight = Gdx.graphics.getHeight(); setScreen(new SplashScreen(this)); } @Override public void render() { super.render(); } }MainMenu代码：
package com.jack.mygdxgame.screens; import com.badlogic.gdx.Game; import com.badlogic.gdx.Gdx; import com.badlogic.gdx.Screen; import com.badlogic.gdx.graphics.GL20; import com.jack.mygdxgame.MyGdxGame; import com.badlogic.gdx.ApplicationAdapter; import com.badlogic.gdx.Gdx; import com.badlogic.gdx.graphics.Color; import com.badlogic.gdx.graphics.GL20; import com.badlogic.gdx.graphics.Pixmap; import static com.badlogic.gdx.graphics.Pixmap.Format.RGB888; import com.badlogic.gdx.graphics.Texture; import com.badlogic.gdx.graphics.g2d.BitmapFont; import com.badlogic.gdx.scenes.scene2d.InputEvent; import com.badlogic.gdx.scenes.scene2d.Stage; import com.badlogic.gdx.scenes.scene2d.ui.TextButton; import com.badlogic.gdx.scenes.scene2d.ui.TextButton.TextButtonStyle; import com.badlogic.gdx.scenes.scene2d.utils.ClickListener; import com.badlogic.gdx.scenes.scene2d.ui.Skin; public class MainMenu implements Screen { Stage stage; Skin skin; private Game game; public MainMenu(Game game) { this.game = game; } public void create() { // load assets int buttonOffSet = 20; stage = new Stage(); Gdx.input.setInputProcessor(stage);// Make the stage consume events createBasicSkin(); TextButton newGameButton = new TextButton("Start game", (com.badlogic.gdx.scenes.scene2d.ui.Skin) skin); // Use the initialized skin newGameButton.setPosition(Gdx.graphics.getWidth() / 2 - Gdx.graphics.getWidth() / 8, Gdx.graphics.getHeight() / 2 + (newGameButton.getHeight() + buttonOffSet)); newGameButton.addListener(new ClickListener() { @Override public void clicked(InputEvent event, float x, float y) { System.out.println("Start game button clicked"); } }); stage.addActor(newGameButton); TextButton loadButton = new TextButton("Load game", (com.badlogic.gdx.scenes.scene2d.ui.Skin) skin); // Use the initialized skin loadButton.setPosition(Gdx.graphics.getWidth() / 2 - Gdx.graphics.getWidth() / 8, Gdx.graphics.getHeight() / 2); loadButton.addListener(new ClickListener() { @Override public void clicked(InputEvent event, float x, float y) { System.out.println("Load Button clicked"); } }); stage.addActor(loadButton); TextButton settingsButton = new TextButton("Settings", (com.badlogic.gdx.scenes.scene2d.ui.Skin) skin); settingsButton.setPosition(Gdx.graphics.getWidth() / 2 - Gdx.graphics.getWidth() / 8, Gdx.graphics.getHeight() / 2 - (settingsButton.getHeight() + buttonOffSet)); settingsButton.addListener(new ClickListener() { @Override public void clicked(InputEvent event, float x, float y) { System.out.println("Settinga Button clicked"); } }); stage.addActor(settingsButton); TextButton exitGameButton = new TextButton("Exit game", (com.badlogic.gdx.scenes.scene2d.ui.Skin) skin); exitGameButton.setPosition(Gdx.graphics.getWidth() / 2 - Gdx.graphics.getWidth() / 8, Gdx.graphics.getHeight() / 2 - 2 * (newGameButton.getHeight() + buttonOffSet)); exitGameButton.addListener(new ClickListener() { @Override public void clicked(InputEvent event, float x, float y) { System.out.println("Exit game button clicked"); System.exit(0); } }); stage.addActor(exitGameButton); } private void createBasicSkin() { //Create a font BitmapFont font = new BitmapFont(); skin = new Skin(); skin.add("default", font); //Create a texture Pixmap pixmap = new Pixmap((int) Gdx.graphics.getWidth() / 4, (int) Gdx.graphics.getHeight() / 10, Pixmap.Format.RGB888); pixmap.setColor(Color.WHITE); pixmap.fill(); skin.add("background", new Texture(pixmap)); //Create a button style TextButton.TextButtonStyle textButtonStyle = new TextButton.TextButtonStyle(); textButtonStyle.up = skin.newDrawable("background", Color.GRAY); textButtonStyle.down = skin.newDrawable("background", Color.DARK_GRAY); textButtonStyle.checked = skin.newDrawable("background", Color.DARK_GRAY); textButtonStyle.over = skin.newDrawable("background", Color.LIGHT_GRAY); textButtonStyle.font = skin.getFont("default"); skin.add("default", textButtonStyle); } @Override public void show() { } @Override public void render(float f) { GL20 gl = Gdx.graphics.getGL20(); gl.glClear(GL20.GL_COLOR_BUFFER_BIT); Gdx.gl.glClearColor(1, 1, 1, 1); stage.act(); stage.draw(); } @Override public void resize(int i, int i1) { } @Override public void pause() { } @Override public void resume() { } @Override public void hide() { } @Override public void dispose() { } }When I run my game and click the screen to exit my splash screen it should bring me to my MainMenu but instead it just freezes. I found the line of code that the error's were telling me but it was no help.(MainMenu.java:124) that line just showed stage.act(); than stage.draw(); if I tried to remove or comment out stage.act();.(MyGdxGame.java:31) then pointed at my super.render();. I have no idea what's wrong, any help at all would be great.
Errors:
Exception in thread "LWJGL Application" java.lang.NullPointerException at com.jack.mygdxgame.screens.MainMenu.render(MainMenu.java:124) at com.badlogic.gdx.Game.render(Game.java:46) at com.jack.mygdxgame.MyGdxGame.render(MyGdxGame.java:31) at com.badlogic.gdx.backends.lwjgl.LwjglApplication.mainLoop(LwjglApplication.java:225) at com.badlogic.gdx.backends.lwjgl.LwjglApplication$1.run(LwjglApplication.java:126)MyGdxGame Code:
package com.jack.mygdxgame; import com.badlogic.gdx.Game; import com.badlogic.gdx.Gdx; import com.badlogic.gdx.Screen; import com.badlogic.gdx.graphics.Texture; import com.badlogic.gdx.graphics.g2d.SpriteBatch; import com.jack.mygdxgame.screens.GameScreen; import com.jack.mygdxgame.splash.SplashScreen; public class MyGdxGame extends Game { public static int nWidth; public static int nHeight; private Game game; public MyGdxGame() { game = this; } @Override public void create() { nWidth = Gdx.graphics.getWidth(); nHeight = Gdx.graphics.getHeight(); setScreen(new SplashScreen(this)); } @Override public void render() { super.render(); } }MainMenu code:
package com.jack.mygdxgame.screens; import com.badlogic.gdx.Game; import com.badlogic.gdx.Gdx; import com.badlogic.gdx.Screen; import com.badlogic.gdx.graphics.GL20; import com.jack.mygdxgame.MyGdxGame; import com.badlogic.gdx.ApplicationAdapter; import com.badlogic.gdx.Gdx; import com.badlogic.gdx.graphics.Color; import com.badlogic.gdx.graphics.GL20; import com.badlogic.gdx.graphics.Pixmap; import static com.badlogic.gdx.graphics.Pixmap.Format.RGB888; import com.badlogic.gdx.graphics.Texture; import com.badlogic.gdx.graphics.g2d.BitmapFont; import com.badlogic.gdx.scenes.scene2d.InputEvent; import com.badlogic.gdx.scenes.scene2d.Stage; import com.badlogic.gdx.scenes.scene2d.ui.TextButton; import com.badlogic.gdx.scenes.scene2d.ui.TextButton.TextButtonStyle; import com.badlogic.gdx.scenes.scene2d.utils.ClickListener; import com.badlogic.gdx.scenes.scene2d.ui.Skin; public class MainMenu implements Screen { Stage stage; Skin skin; private Game game; public MainMenu(Game game) { this.game = game; } public void create() { // load assets int buttonOffSet = 20; stage = new Stage(); Gdx.input.setInputProcessor(stage);// Make the stage consume events createBasicSkin(); TextButton newGameButton = new TextButton("Start game", (com.badlogic.gdx.scenes.scene2d.ui.Skin) skin); // Use the initialized skin newGameButton.setPosition(Gdx.graphics.getWidth() / 2 - Gdx.graphics.getWidth() / 8, Gdx.graphics.getHeight() / 2 + (newGameButton.getHeight() + buttonOffSet)); newGameButton.addListener(new ClickListener() { @Override public void clicked(InputEvent event, float x, float y) { System.out.println("Start game button clicked"); } }); stage.addActor(newGameButton); TextButton loadButton = new TextButton("Load game", (com.badlogic.gdx.scenes.scene2d.ui.Skin) skin); // Use the initialized skin loadButton.setPosition(Gdx.graphics.getWidth() / 2 - Gdx.graphics.getWidth() / 8, Gdx.graphics.getHeight() / 2); loadButton.addListener(new ClickListener() { @Override public void clicked(InputEvent event, float x, float y) { System.out.println("Load Button clicked"); } }); stage.addActor(loadButton); TextButton settingsButton = new TextButton("Settings", (com.badlogic.gdx.scenes.scene2d.ui.Skin) skin); settingsButton.setPosition(Gdx.graphics.getWidth() / 2 - Gdx.graphics.getWidth() / 8, Gdx.graphics.getHeight() / 2 - (settingsButton.getHeight() + buttonOffSet)); settingsButton.addListener(new ClickListener() { @Override public void clicked(InputEvent event, float x, float y) { System.out.println("Settinga Button clicked"); } }); stage.addActor(settingsButton); TextButton exitGameButton = new TextButton("Exit game", (com.badlogic.gdx.scenes.scene2d.ui.Skin) skin); exitGameButton.setPosition(Gdx.graphics.getWidth() / 2 - Gdx.graphics.getWidth() / 8, Gdx.graphics.getHeight() / 2 - 2 * (newGameButton.getHeight() + buttonOffSet)); exitGameButton.addListener(new ClickListener() { @Override public void clicked(InputEvent event, float x, float y) { System.out.println("Exit game button clicked"); System.exit(0); } }); stage.addActor(exitGameButton); } private void createBasicSkin() { //Create a font BitmapFont font = new BitmapFont(); skin = new Skin(); skin.add("default", font); //Create a texture Pixmap pixmap = new Pixmap((int) Gdx.graphics.getWidth() / 4, (int) Gdx.graphics.getHeight() / 10, Pixmap.Format.RGB888); pixmap.setColor(Color.WHITE); pixmap.fill(); skin.add("background", new Texture(pixmap)); //Create a button style TextButton.TextButtonStyle textButtonStyle = new TextButton.TextButtonStyle(); textButtonStyle.up = skin.newDrawable("background", Color.GRAY); textButtonStyle.down = skin.newDrawable("background", Color.DARK_GRAY); textButtonStyle.checked = skin.newDrawable("background", Color.DARK_GRAY); textButtonStyle.over = skin.newDrawable("background", Color.LIGHT_GRAY); textButtonStyle.font = skin.getFont("default"); skin.add("default", textButtonStyle); } @Override public void show() { } @Override public void render(float f) { GL20 gl = Gdx.graphics.getGL20(); gl.glClear(GL20.GL_COLOR_BUFFER_BIT); Gdx.gl.glClearColor(1, 1, 1, 1); stage.act(); stage.draw(); } @Override public void resize(int i, int i1) { } @Override public void pause() { } @Override public void resume() { } @Override public void hide() { } @Override public void dispose() { } }
原文：
更新时间：2022-02-20 09:02
最满意答案
通常当我收到该错误时（警告：轶事），这是因为我在迭代器之后错过了
do关键字，或者是在视图中占用块的haml函数。我没有看到
link_to行有什么问题 - 你可以发布包含错误的文件的来源（并指出哪一行是第23行）？It was a configuration issue. Created a new project, copied my files. Now its working.
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