fragment（一）

碎片的生命周期

1、运行状态

当一个碎片是可见的，并且它所关联的活动正处于运行状态时，该碎片也处于运行状态。

2、暂停状态

当一个活动处于暂停状态时(由于另一个未占满屏幕的活动被添加到栈顶)，与它相关联的可见碎片就会进入到暂停状态。

3、停止状态

当一个活动进入停止状态时，与它相关联的碎片就会进入到停止状态。或者通过调用FragmentTransaction的remove()、replace()方法将碎片从活动中移除，或者在事务提交之前调用addToBackStack()方法，这时碎片也会也会进入到停止状态。

4、销毁状态

碎片总是依附于活动而存在的，因此当活动被销毁时，与它相关联的碎片就会进入到销毁状态，或者调用FragmentTransaction的remove()、replace()方法将碎片从活动中移除，但是在事务提交之前并没有调用addToBackStack()方法，这是碎片也会进入到销毁状态。

firstFragment

public class firstFragment extends Fragment {    private Button mButtonTest;    @Nullable    @Override    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {     View view=inflater.inflate(R.layout.fragment_test,null);        mButtonTest= (Button) view.findViewById(R.id.button_test);       mButtonTest.setOnClickListener(new View.OnClickListener() {           @Override           public void onClick(View v) {               Toast.makeText(getActivity(), "我点击了测试按钮", Toast.LENGTH_SHORT).show();           }       });        return view;    }}

secondFragment

public class secondFragment extends Fragment{private TextView mTextview;    @Nullable    @Override    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {        View view =inflater.inflate(R.layout.fragment_second,null);        mTextview= (TextView) view.findViewById(R.id.textview_1);        return view ;    }    public void setText(String text) {        if (mTextview!=null){            mTextview.setText(text);        }    }}

thirdFragment

public class thirdFragment extends Fragment{    private EditText mEditText;    @Nullable    @Override    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {        View view=inflater.inflate(R.layout.fragment_third,null);        mEditText= (EditText) view.findViewById(R.id.editText);        return view ;    }    public String  getText() {        String s=null;        if (mEditText!=null){            s=mEditText.getText().toString();        }        return s;    }}

MainActivity

public class MainActivity extends FragmentActivity implements View.OnClickListener {    private FrameLayout mFrameContainer;    private Button mBtn1;    private Button mBtn2;    private Button mBtn3;    private firstFragment mfirstFragment;    private secondFragment msecondFragment;    private thirdFragment mthirdFragment;    private FragmentManager mFragmentManager;    private android.support.v4.app.FragmentTransaction mtransaction;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);//        FragmentManager manager=getSupportFragmentManager();        mFrameContainer = (FrameLayout) findViewById(R.id.frame_container);        mBtn1 = (Button) findViewById(R.id.button1);        mBtn2 = (Button) findViewById(R.id.button2);        mBtn3 = (Button) findViewById(R.id.button3);        mBtn1.setOnClickListener(this);        mBtn2.setOnClickListener(this);        mBtn3.setOnClickListener(this);        mFragmentManager = getSupportFragmentManager();        mfirstFragment = new firstFragment();        msecondFragment = new secondFragment();        mthirdFragment = new thirdFragment();        mtransaction = mFragmentManager.beginTransaction();        mtransaction.add(R.id.frame_container, mfirstFragment);        mtransaction.add(R.id.frame_container, msecondFragment);        mtransaction.add(R.id.frame_container, mthirdFragment);        mtransaction.hide(mfirstFragment);        mtransaction.hide(msecondFragment);       // mtransaction.hide(mthirdFragment);        mtransaction.commit();    }    @Override    public void onClick(View v) {        switch (v.getId()) {            case R.id.button1:                mtransaction = mFragmentManager.beginTransaction();                mtransaction.hide(msecondFragment);                mtransaction.hide(mthirdFragment);                mtransaction.show(mfirstFragment);//                mtransaction.replace(R.id.frame_container, new firstFragment());                mtransaction.commit();                break;            case R.id.button2:                mtransaction = mFragmentManager.beginTransaction();                String text = mthirdFragment.getText();                msecondFragment.setText(text);                mtransaction.hide(mfirstFragment);                mtransaction.hide(mthirdFragment);                mtransaction.show(msecondFragment);//                mtransaction.replace(R.id.frame_container, new secondFragment());                mtransaction.commit();                break;            case R.id.button3:                mtransaction = mFragmentManager.beginTransaction();                mtransaction.hide(msecondFragment);                mtransaction.hide(mfirstFragment);                mtransaction.show(mthirdFragment);//                mtransaction.replace(R.id.frame_container, new thirdFragment());                mtransaction.commit();                break;            default:                break;        }    }}

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity"><!--<fragment class="com.example.administrator.myfragment.fragment.firstFragment"-->    <!--android:layout_width="match_parent"-->    <!--android:layout_height="match_parent">--><!--</fragment>-->    <FrameLayout        android:id="@+id/frame_container"        android:layout_width="match_parent"        android:layout_height="match_parent">    </FrameLayout><LinearLayout    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:layout_alignParentBottom="true"    android:orientation="horizontal"    android:gravity="center"><Button    android:id="@+id/button1"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="fragment1"/>    <Button        android:id="@+id/button2"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="fragment2"/>    <Button        android:id="@+id/button3"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="fragment3"/></LinearLayout></RelativeLayout>

fragment_first.xml

<?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">    <Button        android:id="@+id/button_test"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="测试按钮"/></LinearLayout>

fragment_second.xml

<?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"><TextView    android:id="@+id/textview_1"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="我是一个文本"    /></LinearLayout>

fragment_third.xml

<?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"><EditText    android:id="@+id/editText"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:hint="我是内容"/></LinearLayout>

动态添加碎片五部曲

1、创建待添加的碎片实例
2、获取到FragmentManager，在活动中可以直接调用getFragmentManager()方法得到。
3、开启一个事务，通过调用beginTransaction()方法开启。
4、向容器内加入碎片，一般使用replace()方法实现，需要传入容器的id和待添加的碎片实例。
5、提交事务，调用commit()方法来完成。