why are we doing mImageId = imageId; when we already did them at the bottom

Hello,

The below code is the "Constructor" of the class:

public Page(int imageID, String text, Choice choice1, Choice choice2) {
        mImageId = imageID;
        mText = text;
        mChoice1 = choice1;
        mChoice2 = choice2;


    }

This is used only when an object of this class type is instanced. e.g.

Page testPage = new Page(
                        R.mipmap.page1,
                        "hello hello hello",
                        new Choice("Learn Android", 4),
                        new Choice("GiveUp on Android, Learn iOS", 5));

With the above code we have created testPage and an instance of the Page class and have passed in the information required for the parameters. Using those parameters the constructor has assigned them according to the below code:

public Page(int imageID, String text, Choice choice1, Choice choice2) {
        mImageId = imageID;
        mText = text;
        mChoice1 = choice1;
        mChoice2 = choice2;


    }

but what if we want to get the imageId for testPage after initializing it? How do we do that?

That is where the getImageId() method we created comes into play.

we could just say:

testPage.getImageId();

and that will return R.mipmap.page1 the imageId we set in the constructor. If we wanted to update this image id to something else for this object, we could do it like this:

testPage.setImageId(R.mipmap.page3);

that would update the image ID, rather than us having to go down the Constructor route and resetting all the values.

Hopefully that makes it a bit clearer. Let me know if you have a question.