javalibgdx中的屏幕文本实现

我在实现显示和使用玩家用户名的功能时遇到了一些问题。我正在制作一个windows和android之间的跨平台应用程序，我试图在玩家开始键入时显示他们的姓名，可以按enter继续，也可以按级别选择按钮进入下一个屏幕。但每次我按“回车”键时，它都会崩溃。而且，它不会显示或接受玩家的名字。我知道代码不是最优的，比如我制作了多个表，但我希望有人能告诉我哪里犯了错误，这样可能会有用。提前谢谢

代码如下：

package com.paladinzzz.game.screens;

import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.Input;
import com.badlogic.gdx.Screen;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.OrthographicCamera;
import com.badlogic.gdx.graphics.Texture;
import com.badlogic.gdx.graphics.g2d.BitmapFont;
import com.badlogic.gdx.graphics.g2d.TextureRegion;
import com.badlogic.gdx.scenes.scene2d.InputEvent;
import com.badlogic.gdx.scenes.scene2d.Stage;
import com.badlogic.gdx.scenes.scene2d.ui.ImageButton;
import com.badlogic.gdx.scenes.scene2d.ui.Table;
import com.badlogic.gdx.scenes.scene2d.ui.TextButton;
import com.badlogic.gdx.scenes.scene2d.utils.ClickListener;
import com.badlogic.gdx.scenes.scene2d.utils.Drawable;
import com.badlogic.gdx.scenes.scene2d.utils.TextureRegionDrawable;
import com.badlogic.gdx.utils.viewport.FillViewport;
import com.paladinzzz.game.CrossplatformApp;
import com.paladinzzz.game.util.Constants;
import com.paladinzzz.game.audio.MusicHandler;
import static com.badlogic.gdx.Gdx.input;
import static com.paladinzzz.game.screens.MenuScreen.musicHandler;


public class LoginScreen implements Screen {

private CrossplatformApp game;
private Stage stage;
private ImageButton backButton, playButton;
private Texture backTexture, playTexture, background;
private Drawable drawableBack, drawablePlay;
private OrthographicCamera camera;
BitmapFont font = new BitmapFont();
int[] x = new int[255];
public static boolean inPlayscreen = false;
public static String playername = "";
private boolean isConverted = false;
private Table table, table2;

public LoginScreen(CrossplatformApp game) {
    this.game = game;
    this.camera = new OrthographicCamera();
    this.stage = new Stage(new FillViewport(Constants.WIDTH, Constants.HEIGHT, camera));
    this.playTexture = new Texture("Screens/LoginScreen/LvlSelection.png");
    this.backTexture = new Texture("Screens/BackButton.png");
    this.background = new Texture("Screens/LoginScreen/loginscreen.png");
}

@Override
public void show() {

    //Give the texture of the backButton to a new ImageButton
    drawableBack = new TextureRegionDrawable(new TextureRegion(backTexture));
    backButton = new ImageButton(drawableBack);
    backButton.addListener(new ClickListener(){
        @Override
        public void clicked(InputEvent event, float x, float y) {
            game.setScreen(new MenuScreen(game));
            MenuScreen.musicHandler.stopMusic();
        }
    });

    //Give the texture of the playButton to a new ImageButton
    drawablePlay = new TextureRegionDrawable(new TextureRegion(playTexture));
    playButton = new ImageButton(drawablePlay);
    playButton.addListener(new ClickListener(){
        @Override
        public void clicked(InputEvent event, float x, float y) {
            game.setScreen(new LevelScreen(game));
            inPlayscreen = true;
        }
    });


    //Elements can be added here to the stage
    input.setInputProcessor(stage);

    //A table gets made with the button which leads to the level selection screen
    table = new Table();
    table.bottom();
    table.setFillParent(true);
    table.add(playButton).padBottom(40);
    stage.addActor(table);

    //A table gets made with the button which leads back to the main menu
    table2 = new Table();
    table2.bottom();
    table2.setFillParent(true);
    table2.add(backButton).padBottom(13).padRight(640);
    table2.row();
    stage.addActor((table2));
}

@Override
public void render(float delta) {

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

    if(Gdx.input.isKeyJustPressed(Input.Keys.ENTER)){
        game.setScreen(new LevelScreen(game));
        inPlayscreen = true;


        if (!isConverted){
            playername = playername.substring(0, 1).toUpperCase() + playername.substring(1, playername.length()).toLowerCase();
            isConverted = true;
        }
    }

    game.batch.begin();

    //A possibility gets made to insert the name of the player
    game.batch.draw(background, 0, 0, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
    for (int i : x) {
        if (input.isKeyJustPressed(i)){
            if (i != 62 && i != 67 && i!= 66) {
                playername += Input.Keys.toString(i).toLowerCase();
            } else if (i == 67 & playername.length() > 0){
                playername = playername.substring(0, playername.length() - 1).toLowerCase();
            } else {
                playername += " ";
            }
        }
    }

    font.draw(game.batch, playername, 0, 0);

    game.batch.end();
    stage.draw();
}

@Override
public void resize(int width, int height) {

}

@Override
public void pause() {

}

@Override
public void resume() {

}

@Override
public void hide() {

}

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

}
}

这就是“登录屏幕”的外观：

这是错误消息：

Exception in thread "LWJGL Application" 
java.lang.StringIndexOutOfBoundsException: String index out of range: 1
at java.lang.String.substring(String.java:1963)
at com.paladinzzz.game.screens.LoginScreen.render(LoginScreen.java:108)
at com.badlogic.gdx.Game.render(Game.java:46)
at com.paladinzzz.game.CrossplatformApp.render(CrossplatformApp.java:30)
at com.badlogic.gdx.backends.lwjgl.LwjglApplication.mainLoop(LwjglApplication.java:225)
at com.badlogic.gdx.backends.lwjgl.LwjglApplication$1.run(LwjglApplication.java:126)

使用断点进行调试：

---

此线路的故障解决方案是：

playername = playername.substring(0, 1).toUpperCase() + playername.substring(1, playername.length()).toLowerCase();

您的第二个子字符串需要使用

playername.length()-1

---

我只是快速浏览了一下你的代码，所以我不能100%确定这是否是解决方案，但我注意到你自己构建了一个非常“有趣”的输入例程。也许你也推动了输入处理器并使用它的输入。（稍后我会仔细看一看。我现在很忙编辑：你能发布stacktrace以获取更多关于崩溃的信息吗？刚刚做了，也许这会澄清问题。谢谢。我看到“字符串超出范围：1”，但即使我键入一些内容并按enter键，它也不起作用，所以这就是我提出此问题的原因添加bre在崩溃之前点击并检查调试器中的值。你的playername值是多少？编辑：你的第二个子串从0开始计数，所以你需要长度（）-1抱歉，花了这么长时间，我试图自己修复它，但显然没有真正起作用。它还说“playername”里面除了“playername”之外什么都没有。我会在帖子中放一个调试的屏幕截图。你实现了我发布在这里的解决方案吗？你的图像崩溃是因为你有一个长度为0的字符串并开始拾取索引1中的子字符串。如果操纵字符串，可能还需要确保字符串足够长；如果字符串太短，则可能未被操纵。我将其转换为“playername=playername.substring（-1，1）.toUpperCase（）+playername.substring（1，playername.length（）-1）.toLowerCase（）；“”因此，即使没有任何内容，它也可以减少-1，换句话说，当它为0时，但这也会使它崩溃。您无法创建负索引的子字符串。将字符串想象为数组（char数组）。你不能访问一个有意义的无效indexOkay..忘记了..但即使我将其转换为

playername=playername.substring（1，2）.toUpperCase（）+playername.substring（2，playername.length（）-1）.toLowerCase（）；

值也不会增加