Android Fragment使用

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

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/testview" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/button" />

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:baselineAligned="false"
    android:orientation="horizontal" >

    <fragment
        android:id="@+id/first"
        android:name="com.example.FristFragment"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="1" />

    <fragment
        android:id="@+id/second"
        android:name="com.example.SecondFragment"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="1" />

</LinearLayout>

• 用android:id属性提供一个唯一的标识
• 用android:tag属性提供一个唯一的字符串
• 如果上述两个属性都没有，系统会使用其容器视图的ID

	FragmentManager fragmentManager = getFragmentManager()
	FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
	ExampleFragment fragment = new ExampleFragment();
	fragmentTransaction.add(R.id.fragment_container, fragment);
	fragmentTransaction.commit();

import android.os.Bundle;
import android.support.v4.app.Fragment;

public class TestFragment extends Fragment {
	public static TestFragment newInstance(int num, String title) {
		TestFragment fragment = new TestFragment();
		Bundle args = new Bundle();
		args.putInt("num", num);
		args.putString("title", title);
		fragment.setArguments(args);
		return fragment;
	}

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);

		int num = getArguments().getInt("num", 0);
		String title = getArguments().getString("title", "");
	}

}

FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
TestFragment fragment = TestFragment.newInstance(5, "fragment title");
ft.replace(R.id.placeholder, fragment);
ft.commit();

调用Fragment的方法

public class TestFragment extends Fragment {
	public void doSomething(String param) {
		// do something in fragment
	}
}

public class MainActivity extends FragmentActivity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        TestFragment testFragment = new TestFragment();
        testFragment.doSomething("some param");
    }
}

import android.support.v4.app.Fragment;

public class MyListFragment extends Fragment {
  // ...
  // Define the listener of the interface type
  // listener is the activity itself
  private OnItemSelectedListener listener;

  // Define the events that the fragment will use to communicate
  public interface OnItemSelectedListener {
    public void onRssItemSelected(String link);
  }

  // Store the listener (activity) that will have events fired once the fragment is attached
  @Override
  public void onAttach(Activity activity) {
    super.onAttach(activity);
      if (activity instanceof OnItemSelectedListener) {
        listener = (OnItemSelectedListener) activity;
      } else {
        throw new ClassCastException(activity.toString()
            + " must implement MyListFragment.OnItemSelectedListener");
      }
  }

  // Now we can fire the event when the user selects something in the fragment
  public void onSomeClick(View v) {
     listener.onRssItemSelected("some link");
  }
}

import android.support.v4.app.FragmentActivity;

public class RssfeedActivity extends FragmentActivity implements
  MyListFragment.OnItemSelectedListener {
    DetailFragment fragment;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_rssfeed);
      fragment = (DetailFragment) getSupportFragmentManager()
            .findFragmentById(R.id.detailFragment);
  }

  // Now we can define the action to take in the activity when the fragment event fires
  @Override
  public void onRssItemSelected(String link) {
      if (fragment != null && fragment.isInLayout()) {
          fragment.setText(link);
      }
  }
}