AlertDialog完美地显示内容和按钮，直到内容增长到需要滚动才能显示所有内容为止。此时，即使列表完整显示，按钮也会消失。

我看到在过去的几年里，有人问过这个问题（这个问题基本上与我的问题（DialogFragment buttons pushed off screen API 24 and above相同），但是答案似乎都是命中注定的，甚至偶然的：设置layout_weight，从setMessage（）切换设置为setTitle（），最后从AlertDialog切换到Dialog。

这些都不对我有用，并且避免使用AlertDialog并不是一个吸引人的选择，因为我正在使用setMultiChoiceItems（）方法，该方法似乎（对于我来说是不可思议的，也许是因为我的知识非常有限）只能用于AlertDialog。

在绝望和沮丧中，我直接吸引了stackoverflow的集体大脑。

这是我的DialogFragment的简化版本：

public class SurfaceDialog extends DialogFragment {
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {

        AlertDialog.Builder builder = new AlertDialog.Builder(getactivity());
        LayoutInflater inflater = requireactivity().getLayoutInflater();
        builder.setView(inflater.inflate(R.layout.surface_dialog,null))
                .setTitle(mMessage)
                .setMultiChoiceItems(mSurfaceList,mCheckedSurfaces,new DialogInterface.OnmultiChoiceclicklistener() {
                    @Override
                    public void onClick(DialogInterface dialog,int which,boolean isChecked) {
                        if (isChecked) {
                            mCheckedSurfacesPositions.add(which);
                        } else {
                            mCheckedSurfacesPositions.remove(mCheckedSurfacesPositions.indexOf(which));
                        }
                    }
                });

        // builder.setCancelable(false);
        builder.setPositiveButton("Done",new DialogInterface.OnClicklistener() {
            @Override
            public void onClick(DialogInterface dialog,int which) {
                ProcessDialogSelections(mCheckedSurfacesPositions);
                dismiss();
            }

        }).setNegativeButton("Cancel",int which) {
                listener.onSurfaceDialogSelectedSent(mUnitSurfaces);
                dismiss();
            }
        });

        return builder.create();
    }

那不起作用，然后我编码了自己的按钮并显示了它们：

    public Dialog onCreateDialog(Bundle savedInstanceState) {
        AlertDialog.Builder builder = new AlertDialog.Builder(getactivity());
        LayoutInflater inflater = requireactivity().getLayoutInflater();
        View dialogView = inflater.inflate(R.layout.surface_dialog,null);
        builder.setView(dialogView)
                .setTitle(mMessage)

                .setMultiChoiceItems(mSurfaceList,boolean isChecked) {
                        if (isChecked) {
                            mCheckedSurfacesPositions.add(which);
                        } else {
                            mCheckedSurfacesPositions.remove(mCheckedSurfacesPositions.indexOf(which));
                        }
                    }
                });

        Button positiveButton = dialogView.findViewById(R.id.positive_button);
        Button negativeButton = dialogView.findViewById(R.id.negative_button);

        positiveButton.setOnClicklistener(new View.OnClicklistener() {
            @Override
            public void onClick(View v) {
                ProcessDialogSelections(mCheckedSurfacesPositions);
                dismiss();
            }
        });
        negativeButton.setOnClicklistener(new View.OnClicklistener() {
            @Override
            public void onClick(View v) {
                listener.onSurfaceDialogSelectedSent(mUnitSurfaces);
                dismiss();
            }
        });

        return builder.create();

    }

这是我修改后的XML文件

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout android:layout_height="match_parent"
    android:layout_width="match_parent"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintBottom_toBottomOf="parent"
        android:orientation="vertical">

    </ScrollView>


    <Button
        android:id="@+id/positive_button"
        android:layout_height="wrap_content"
        android:layout_marginBottom="30dp"
        android:layout_width="wrap_content"
        android:text="Done"
        app:layout_constraintBaseline_toBaselineOf="@+id/negative_button"
        app:layout_constraintEnd_toStartOf="@+id/negative_button"
        app:layout_constraintStart_toStartOf="parent" />

    <Button
        android:id="@+id/negative_button"
        android:layout_height="wrap_content"
        android:layout_marginBottom="30dp"
        android:layout_width="wrap_content"
        android:text="Cancel"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/positive_button" />

</androidx.constraintlayout.widget.ConstraintLayout>

在没有任何效果的情况下，我遵循了Vikas Singh（AlertDialog Buttons not visible when using Custom layout）的建议。这就是新代码的样子（基本上是用Java而不是XML创建布局。

    public Dialog onCreateDialog(Bundle savedInstanceState) {

        AlertDialog.Builder builder = new AlertDialog.Builder(getactivity());

        // New code from Vikas Singh
        LinearLayout rootLayout = new LinearLayout(getactivity());
        rootLayout.setOrientation(LinearLayout.VERTICAL);
        ScrollView scrollView = new ScrollView(getactivity());
        LinearLayout layout = new LinearLayout(getactivity());
        layout.setOrientation(LinearLayout.VERTICAL);

        scrollView.addView(layout);
        rootLayout.addView(scrollView);
        builder.setNegativeButton("Cancel",null);
        builder.setPositiveButton("Go",null);
        builder.setView(rootLayout);

        builder//.setView(dialogView)
                //.setTitle(mMessage)

                .setMultiChoiceItems(mSurfaceList,boolean isChecked) {
                        if (isChecked) {
                            mCheckedSurfacesPositions.add(which);
                        } else {
                            mCheckedSurfacesPositions.remove(mCheckedSurfacesPositions.indexOf(which));
                        }
                    }
                });
        return builder.create();
    }

当我必须滚动时，仍然没有按钮。 为什么不呢，我该怎么办？