[android] How to prevent a dialog from closing when a button is clicked

Use a custom layout for your DialogFragment and add a LinearLayout under your content which can be styled as borderless to match Google Material Design. Then find the newly created buttons and override their OnClickListener.

Example:

public class AddTopicFragment extends DialogFragment {

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        final AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
        // Get the layout inflater
        LayoutInflater inflater = getActivity().getLayoutInflater();
        final View dialogView = inflater.inflate(R.layout.dialog_add_topic, null);

        Button saveTopicDialogButton = (Button) dialogView.findViewById(R.id.saveTopicDialogButton);
        Button cancelSaveTopicDialogButton = (Button) dialogView.findViewById(R.id.cancelSaveTopicDialogButton);

        final AppCompatEditText addTopicNameET = (AppCompatEditText) dialogView.findViewById(R.id.addTopicNameET);
        final AppCompatEditText addTopicCreatedByET = (AppCompatEditText) dialogView.findViewById(R.id.addTopicCreatedByET);

        saveTopicDialogButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // validate inputs
                if(addTopicNameET.getText().toString().trim().isEmpty()){
                    addTopicNameET.setError("Topic name can't be empty");
                    addTopicNameET.requestFocus();
                }else if(addTopicCreatedByET.getText().toString().trim().isEmpty()){
                    addTopicCreatedByET.setError("Topic created by can't be empty");
                    addTopicCreatedByET.requestFocus();
                }else {
                    // save topic to database
                    Topic topic = new Topic();
                    topic.name = addTopicNameET.getText().toString().trim();
                    topic.createdBy = addTopicCreatedByET.getText().toString().trim();
                    topic.createdDate = new Date().getTime();
                    topic.save();
                    AddTopicFragment.this.dismiss();
                }
            }
        });

        cancelSaveTopicDialogButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                AddTopicFragment.this.dismiss();
            }
        });

        // Inflate and set the layout for the dialog
        // Pass null as the parent view because its going in the dialog layout
        builder.setView(dialogView)
               .setMessage(getString(R.string.add_topic_message));

        return builder.create();
    }

}

dialog_add_topic.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:padding="@dimen/activity_horizontal_margin"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.design.widget.TextInputLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:errorEnabled="true">

        <android.support.v7.widget.AppCompatEditText
            android:id="@+id/addTopicNameET"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="Topic Name"
            android:inputType="textPersonName"
            android:maxLines="1" />

    </android.support.design.widget.TextInputLayout>

    <android.support.design.widget.TextInputLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:errorEnabled="true">

        <android.support.v7.widget.AppCompatEditText
            android:id="@+id/addTopicCreatedByET"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="Created By"
            android:inputType="textPersonName"
            android:maxLines="1" />

    </android.support.design.widget.TextInputLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
        <Button
            android:text="@string/cancel"
            android:layout_weight="1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:id="@+id/cancelSaveTopicDialogButton"
            style="@style/Widget.AppCompat.Button.ButtonBar.AlertDialog" />

        <Button
            android:text="@string/save"
            android:layout_weight="1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:id="@+id/saveTopicDialogButton"
            style="@style/Widget.AppCompat.Button.ButtonBar.AlertDialog" />

    </LinearLayout>


</LinearLayout>

This is the final result.