Android Fragment是Android4.0以上才有的；而FragmentActivity是为了兼容4.0以下版本的Fragment使用的。
所以如果你想兼容4.0以下Android版本使用Fragment的话，框架Activity需要继承FragmentActivity，FragmentActivity这个类是在android.support.v4.app.FragmentActivity里的。
下面介绍2种用法：
1、继承Activity的。
（这个只针对4.0以上的Android平台使用Fragment）。
框架Activity：
package com.tandong.fragment; import android.app.Activity; import android.app.Fragment; import android.app.FragmentManager; import android.app.FragmentTransaction; import android.os.Bundle; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; /** * 不兼容4.0以下模式Fragment * * @author tandong * */ public class Mt_Activity extends Activity implements OnClickListener { private Button btn_first, btn_second; private Fragment Fragment_first, Fragment_Second; private FragmentTransaction fragmentTransaction; private FragmentManager fragmentManager; @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); setContentView(R.layout.fragment); initView(); Fragment_Second = new Fragment_Second(); fragmentManager = this.getFragmentManager(); fragmentTransaction = fragmentManager.beginTransaction(); fragmentTransaction.replace(R.id.main_fragment_layout, Fragment_Second,"second_Fragment"); fragmentTransaction.commit(); } private void initView() { btn_first = (Button) this.findViewById(R.id.btn_first); btn_second = (Button) this.findViewById(R.id.btn_second); btn_first.setOnClickListener(this); btn_second.setOnClickListener(this); } @Override public void onClick(View arg0) { switch (arg0.getId()) { case R.id.btn_first: // 加载不同的Fragment if (null == Fragment_first) { Fragment_first = new Fragment_first(); } fragmentTransaction = fragmentManager.beginTransaction(); fragmentTransaction.replace(R.id.main_fragment_layout, Fragment_first, "fist_Fragment"); fragmentTransaction.commit(); break; case R.id.btn_second: if (null == Fragment_first) { Fragment_Second = new Fragment_Second(); } fragmentTransaction = fragmentManager.beginTransaction(); fragmentTransaction.replace(R.id.main_fragment_layout, Fragment_Second, "second_Fragment"); fragmentTransaction.commit(); break; default: break; } } }
Fragment代码：
package com.tandong.fragment; import android.app.Fragment; import android.os.Bundle; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; public class Fragment_Second extends Fragment { private View rootView; @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { if(container==null) return null; rootView = inflater.inflate(R.layout.fragment_two, container,false); return rootView; } }
2.继承FragmentActivity的（向下兼容4.0以下版本使用Fragment，导入的是android.support.v4包里的内容）
框架Activity：
package com.tandong.fragment; import android.os.Bundle; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentActivity; import android.support.v4.app.FragmentManager; import android.support.v4.app.FragmentTransaction; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; /** * 兼容4.0以下模式Fragment * * @author tandong * */ public class Mt_Activity extends FragmentActivity implements OnClickListener { private Button btn_first, btn_second; private Fragment Fragment_first, Fragment_Second; private FragmentTransaction fragmentTransaction; private FragmentManager fragmentManager; @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); setContentView(R.layout.fragment); initView(); Fragment_first = new Fragment_first(); fragmentManager = this.getSupportFragmentManager(); fragmentTransaction = fragmentManager.beginTransaction(); fragmentTransaction.replace(R.id.main_fragment_layout, Fragment_first,"first_Fragment"); fragmentTransaction.commit(); } private void initView() { btn_first = (Button) this.findViewById(R.id.btn_first); btn_second = (Button) this.findViewById(R.id.btn_second); btn_first.setOnClickListener(this); btn_second.setOnClickListener(this); } @Override public void onClick(View arg0) { switch (arg0.getId()) { case R.id.btn_first: // 加载不同的Fragment if (null == Fragment_first) { Fragment_first = new Fragment_first(); } fragmentTransaction = fragmentManager.beginTransaction(); fragmentTransaction.replace(R.id.main_fragment_layout, Fragment_first, "fist_Fragment"); fragmentTransaction.commit(); break; case R.id.btn_second: if (null == Fragment_first) { Fragment_Second = new Fragment_Second(); } fragmentTransaction = fragmentManager.beginTransaction(); fragmentTransaction.replace(R.id.main_fragment_layout, Fragment_Second, "second_Fragment"); fragmentTransaction.commit(); break; default: break; } } }
Fragment代码：
package com.tandong.fragment; import android.os.Bundle; import android.support.v4.app.Fragment; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; public class Fragment_first extends Fragment { private View rootView; @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { if(container==null) return null; rootView = inflater.inflate(R.layout.fragment_first, container,false); return rootView; } }
最后再说一句布局：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" > <LinearLayout android:id="@+id/top_bar_layout" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_alignParentTop="true" android:orientation="horizontal" > <Button android:id="@+id/btn_one" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="1" android:background="@drawable/top_bar_bg" android:text="按钮一" /> <Button android:id="@+id/btn_two" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="1" android:background="@drawable/top_bar_bg" android:text="按钮二" /> </LinearLayout> <LinearLayout android:id="@+id/fragment_replace_layout" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_below="@id/top_bar_layout" android:background="#ff0000" > </LinearLayout> </RelativeLayout>
布局类似这种布局即可，并不是一定非要FrameLayout