销毁并重新创建活动后处理重新创建的对话框片段的最佳方法

Question

I have an activity which may show some DialogFragments. This activity needs to get the response from the dialogs. I use a listener. In activity:

ProgressMarkDialog dialog = new ProgressMarkDialog();
dialog.setOnProgressMarkSelected(new ProgressMarkDialog.OnProgressMarkSelected() {
    @Override
    public void onSelect(final int a) {
    //some code..
        }
});

In the dialog:

public void setOnProgressMarkSelected(OnProgressMarkSelected onProgressMarkSelected) {
    this.onProgressMarkSelected = onProgressMarkSelected;
}

This code works fine until somehow the activity is destroyed, but the dialog still open. The program will crash with NullPointerException because the onProgressMarkSelected is null.

I can use

@Override
public void onAttach(final Activity activity) {
    super.onAttach(activity);
    onProgressMarkSelected = (OnProgressMarkSelected) activity;
}

and implement the interface in the activity. But if I have few DialogFragments, that means I should implement few interface in the activity and the code will be very messy. What is the Android best practice for this case?

Answer 1

In my opinion the best way is to stick to the standard positive/negative buttons and attaching DialogInterface.OnClickListener as shown in the http://developer.android.com/reference/android/app/DialogFragment.html

Look at it this way: standard Android user expects to see positive and/or negative button in the dialog. The Activity -if needed- should only be informed about the result (positive, negative input data) of the dialog. Any other input validation should be handled inside the DialogFragment

Answer 2

You could use inheritance with interfaces. Because on interfaces multiple inheritance is possible like this:

public interface A(){
    void doA();
}

public interface B(){
    void doB();
}

public interface BundleAB extends A, B {
    void justAnotherMethod();
}

With this you can bundle your interfaces and use it like this:

public class MyClass implements BundleAB {
    @Override
    public void doA(){}

    @Override
    public void doB(){}

    @Override
    public void justAnotherMethod(){}
}