[Android] 利用ViewPager切換Fragment

照之前紀錄的方法實作，發現我無法去讀取ViewPager中layout的控制項，所以再以之前實作的方法為基礎，但改成切換Fragment的方式，以便可以操控layout中的控制項。

Step1 在activity_main.xml中加入ViewPager標籤

	<android.support.v4.view.ViewPager
	android:layout_width="match_parent"
	android:layout_height="match_parent"
	android:id="@+id/pager">
	</android.support.v4.view.ViewPager>

view raw activity_main.xml hosted with ❤ by GitHub

Step2 新增要切換的layout

	<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
	android:layout_width="match_parent"
	android:layout_height="match_parent"
	android:orientation="vertical"
	android:gravity="center">
	<TextView
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"
	android:text="01"/>
	</LinearLayout>

view raw layout1.xml hosted with ❤ by GitHub

另外一個頁面：layout2為一樣的實作方法

Step3 新增layout相對應的Fragment

	public class Fragment1 extends Fragment {
	@Nullable
	@Override
	public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
	View view = inflater.inflate(R.layout.layout1, container,
	false);
	return view;
	}
	}

view raw Fragment1.java hosted with ❤ by GitHub

另外一個頁面：Fragment2為一樣的實作方法

Step4 在MainActivity.java中新增ViewPagerAdapter的class

	public class ViewPagerAdapter extends FragmentPagerAdapter {
	public ViewPagerAdapter(FragmentManager fm) {
	super(fm);
	}
	@Override
	public Fragment getItem(int position) {
	switch (position) {
	case 0:
	return new Fragment1();
	case 1:
	return new Fragment2();
	default:
	return null;
	}
	}
	//要切換的頁面數量
	@Override
	public int getCount() {
	return 2;
	}
	}

view raw MainActivity.java hosted with ❤ by GitHub

Step5 在MainActivity.java中設定PagerAdapter

	private ViewPager mViewPager;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);
	setContentView(R.layout.activity_main);
	mViewPager = (ViewPager) findViewById(R.id.pager);
	mViewPager.setAdapter(new ViewPagerAdapter(getSupportFragmentManager()));
	}

view raw MainActivity.java hosted with ❤ by GitHub

執行結果：