使用这段代码，它是为我工作:

Dialog dialog = new Dialog(getActivity(),android.R.style.Theme_Translucent_NoTitleBar);
dialog.show();

与zGnep相同的解决方案，但使用xml:

android:background="@null"

你可以使用:

setBackgroundDrawable(null);

方法。下面是文档:

  /**
    * Set the background to a given Drawable, or remove the background. If the
    * background has padding, this View's padding is set to the background's
    * padding. However, when a background is removed, this View's padding isn't
    * touched. If setting the padding is desired, please use
    * {@link #setPadding(int, int, int, int)}.
    *
    * @param d The Drawable to use as the background, or null to remove the
    *        background
    */

在Kotlin中，你可以使用以下代码:

val dialog = Dialog(context)
dialog.window?.decorView?.background = null

使用这段代码，它是为我工作:

Dialog dialog = new Dialog(getActivity(),android.R.style.Theme_Translucent_NoTitleBar);
dialog.show();

对话框弹出填充默认的黑色背景颜色或主题颜色，所以你需要设置透明的背景到对话框。试试下面的代码:-

final Dialog dialog = new Dialog(this);
dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
dialog.getWindow().setBackgroundDrawable(new ColorDrawable(android.graphics.Color.TRANSPARENT));
dialog.setContentView(R.layout.splash);
dialog.show();