Android Viewpager Ch 11

Front 1

What does ViewPager let users do?

Back 1

swipe across the screen to access different parts of the app

Front 2

How do you (generally) use ViewPager?

Back 2

create a new activity where its layout consists of a ViewPager

Front 3

If your view hierarchy is very simple (just a single View), what can you do?

Back 3

Don't bother creating an xml file. Instead, create that one view in the java code. however, keep in mind that if it requires a resource, you'll need to create a new xml file called res/values/ids.xml and define the id in it

Front 4

xml to create a standalone resource id

Back 4

< item type="id" name="viewPager" />

Front 5

steps for creating a viewPager in the code instead of xml

Back 5

- create a resource ID for ViewPager

- create an instance of ViewPager and assign it to mViewPager

- configure it by assigning a resource ID to it

- set your ViewPager as the content view of your activity

Front 6

syntax to create content view programmatically for ViewPager

Back 6

mViewPager = new ViewPager(this);

mViewPager.setId(R.id.viewPager);

setContentView(mViewPager);

Front 7

What other things do you need to use with ViewPager?

Back 7

PagerAdapter and FragmentStatePagerAdapter

FragmentStatePagerAdapter makes the conversation with PagerAdapter simpler

Front 8

To what methods does FragmentStatePagerAdapter pare down the conversation between ViewPager and PagerAdapter?

Back 8

getCount() ---> for number of items it can switch between

getItem(int)

Front 9

Syntax for adding PagerAdapter and FragmentStatePagerAdapter

Back 9

mViewPager.setAdapter(new FragmentStatePagerAdapter(fm) { @Override public Fragment getItem(int position) {

Crime crime = mCrimes.get(position);

return CrimeFragment.newInstance(crime.getmId()); }

@Override public int getCount() {

return mCrimes.size(); }});

Front 10

What pages does ViewPager load by default?

Back 10

current page and one to either side for smooth use

Front 11

How do you change how many pages ViewPager loads?

Back 11

setOffscreenPageLimit(int)

Front 12

By default, ViewPager shows the first item in its PagerAdapter. How do you change what it shows? For example, how would you change it so it shows something related to the particular thing you swiped?

Back 12

in onCreate(){

mViewPager.setCurrentItem(int)

Front 13

How do you listen for changes in the page currently being displayed by ViewPager?

Back 13

OnPageListener(...)

Front 14

FragmentStatePagerAdapter vs FragmentPagerAdapter

Back 14

With FragmentStatePagerAdapter, your unneeded Fragment is destroyed. In FragmentPagerAdapter, the view is detached but not destroyed, so it remains active in the FragmentManager