只是简单的一个!在你的Java类中创建一个dialog方法，就像这样:

public void openDialog() {
    final Dialog dialog = new Dialog(context); // Context, this, etc.
    dialog.setContentView(R.layout.dialog_demo);
    dialog.setTitle(R.string.dialog_title);
    dialog.show();
}

现在创建布局XML dialog_demo.xml并创建UI/设计。下面是我为演示目的创建的一个示例:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <TextView
        android:id="@+id/dialog_info"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:padding="10dp"
        android:text="@string/dialog_text"/>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:layout_below="@id/dialog_info">

        <Button
            android:id="@+id/dialog_cancel"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="0.50"
            android:background="@color/dialog_cancel_bgcolor"
            android:text="Cancel"/>

        <Button
            android:id="@+id/dialog_ok"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="0.50"
            android:background="@color/dialog_ok_bgcolor"
            android:text="Agree"/>
    </LinearLayout>
</RelativeLayout>

现在你可以从任何你喜欢的地方调用openDialog():)下面是上面代码的截图。

注意，文本和颜色来自strings.xml和colors.xml。你可以定义你自己的。

创建这个静态方法，并在任何需要的地方使用它。

public static void showAlertDialog(Context context, String title, String message, String posBtnMsg, String negBtnMsg) {
            AlertDialog.Builder builder = new AlertDialog.Builder(context);
            builder.setTitle(title);
            builder.setMessage(message);
            builder.setPositiveButton(posBtnMsg, new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    dialog.cancel();
                }
            });
            builder.setNegativeButton(negBtnMsg, new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    dialog.cancel();
                }
            });
            AlertDialog dialog = builder.create();
            dialog.show();

        }

你可以试试这个....

    AlertDialog.Builder dialog = new AlertDialog.Builder(MainActivity.this);
dialog.setCancelable(false);
dialog.setTitle("Dialog on Android");
dialog.setMessage("Are you sure you want to delete this entry?" );
dialog.setPositiveButton("Delete", new DialogInterface.OnClickListener() {
    @Override
    public void onClick(DialogInterface dialog, int id) {
        //Action for "Delete".
    }
})
        .setNegativeButton("Cancel ", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
            //Action for "Cancel".
            }
        });

final AlertDialog alert = dialog.create();
alert.show();

欲了解更多信息，请查看此链接…

AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setTitle("This is Title");
    builder.setMessage("This is message for Alert Dialog");
    builder.setPositiveButton("Positive Button", (dialog, which) -> onBackPressed());
    builder.setNegativeButton("Negative Button", (dialog, which) -> dialog.cancel());
    builder.show();

这是一种类似于用一行代码创建Alert对话框的方法。

您可以为此使用AlertDialog，并使用它的Builder类构造一个AlertDialog。下面的例子使用默认的构造函数，它只接受Context，因为对话框将从传入的Context继承适当的主题，但是如果你想这样做，还有一个构造函数允许你指定一个特定的主题资源作为第二个参数。

new AlertDialog.Builder(context)
    .setTitle("Delete entry")
    .setMessage("Are you sure you want to delete this entry?")

    // Specifying a listener allows you to take an action before dismissing the dialog.
    // The dialog is automatically dismissed when a dialog button is clicked.
    .setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int which) { 
            // Continue with delete operation
        }
     })

    // A null listener allows the button to dismiss the dialog and take no further action.
    .setNegativeButton(android.R.string.no, null)
    .setIcon(android.R.drawable.ic_dialog_alert)
    .show();

   new AlertDialog.Builder(v.getContext()).setMessage("msg to display!").show();