Java 运行时imageview未显示在启动程序活动中

使用下面的代码，我的背景图像不会显示在启动屏幕的活动中。 我还有一个睡眠时间为3秒的线程，但我只看到白色屏幕作为背景。延迟之后，我重定向到另一个活动（在OnStart函数中）。 没有重定向，我将图像视为背景。 在重定向到第二个活动之前，如何查看launchscreen图像

提前谢谢你的帮助

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    mContext = this;
    mAuth = FirebaseAuth.getInstance();

            RequestOptions options = new RequestOptions();
            options.centerCrop();

            RelativeLayout relativeLayout = new RelativeLayout(mContext);
            RelativeLayout.LayoutParams relLayoutParam = new RelativeLayout.LayoutParams(
                    RelativeLayout.LayoutParams.MATCH_PARENT, RelativeLayout.LayoutParams.MATCH_PARENT);
            imageView = new ImageView(mContext);
            imageView.setScaleType(ImageView.ScaleType.FIT_CENTER);
            imageView.setBackgroundResource(R.drawable.launch_screen_image);
            relativeLayout.addView(imageView, relLayoutParam);

            setContentView(relativeLayout, relLayoutParam);
            try {
                Thread.sleep(3000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

}

@Override
public void onStart() {
    super.onStart();
    // Check if user is signed in (non-null) and update UI accordingly.
    SharedPreferences mPrefs = PreferenceManager.getDefaultSharedPreferences(this);
    FirebaseUser currentUser = mAuth.getCurrentUser();
    if (currentUser != null && currentUser.getUid() != null
            && currentUser.getUid().equals(mPrefs.getString("UID", "DEFAULT"))) {
        Intent i = new Intent(mContext, SocialPage.class);
        startActivity(i);
    } else {
        Intent i = new Intent(mContext, Login.class);
        startActivity(i);
    }
}

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是的，这是因为您没有为不同分辨率的设备管理不同图像大小的dpi

如果在可绘制文件夹中复制时，所有设备的分辨率只有一个图像，请将图像添加为nodpi，如图所示。所以，如果没有特定分辨率的图像，它将自动从drawable的nodpi中获取图像

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试试这个，用代码中的注释解释每一行：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

        //Other stuff
        //...
            //Remove this line ==> imageView.setBackgroundResource(R.drawable.launch_screen_image);
            relativeLayout.addView(imageView, relLayoutParam);

            setContentView(relativeLayout, relLayoutParam);

            //set image resource after setContentView
            imageView.setImageResource(R.drawable.launch_screen_image);

            //Use handler instead of Thread.sleep()
            new Handler().postDelayed(new Runnable() {
                @Override
                public void run() {
                    //it calls continue() after 3 seconds of delay
                    continue();
                }
            },3000);


}

和continue（）方法包括：

private void continue(){

    // Check if user is signed in (non-null) and update UI accordingly.
    SharedPreferences mPrefs = PreferenceManager.getDefaultSharedPreferences(this);
    FirebaseUser currentUser = mAuth.getCurrentUser();
    if (currentUser != null && currentUser.getUid() != null
            && currentUser.getUid().equals(mPrefs.getString("UID", "DEFAULT"))) {
        Intent i = new Intent(mContext, SocialPage.class);
        startActivity(i);
    } else {
        Intent i = new Intent(mContext, Login.class);
        startActivity(i);
    }


}

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使用背景主题或在xml类中添加imageview