利用fragment实现界面跳转

• 任务要求
  利用fragment实现界面跳转功能，完成效果如下图所示
  图片1

我的想法是在xml文件里设置Button。再创建一个fragment文件。在java文件中动态加载fragment完成第一张效果。点击按钮后在动态加载一张fragment实现setcontent方法改写内容字符串。点击返回键返回第一张fragment
xml文件

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:tools="http://schemas.android.com/tools"android:id="@+id/activity_main"android:layout_width="match_parent"android:layout_height="match_parent"android:paddingBottom="@dimen/activity_vertical_margin"android:paddingLeft="@dimen/activity_horizontal_margin"android:paddingRight="@dimen/activity_horizontal_margin"android:paddingTop="@dimen/activity_vertical_margin"tools:context="com.example.administrator.interfacejunmp.MainActivity"><LinearLayoutandroid:layout_width="match_parent"android:layout_height="wrap_content"android:orientation="horizontal"android:layout_alignParentBottom="true"><Buttonandroid:id="@+id/first"android:layout_width="match_parent"android:layout_height="wrap_content"style="@style/ZT1"/></LinearLayout>
</RelativeLayout>

fragment文件

<FrameLayout 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"tools:context="com.example.administrator.interfacejunmp.MyFragment"><!-- TODO: Update blank fragment layout --><TextViewandroid:id="@+id/txt_show"android:layout_width="match_parent"android:layout_height="match_parent"android:text="@string/this_is_first_fragment"android:gravity="center"style="@style/ZT3"/>
</FrameLayout>

java代码
activity

public class MainActivity extends AppCompatActivity implements View.OnClickListener {private MyFragment g1;private Button first;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);Button first = (Button)findViewById(R.id.first);first.setOnClickListener(this);FragmentManager ft = getFragmentManager();FragmentTransaction fc= ft.beginTransaction();g1 = new MyFragment();fc.add(R.id.activity_main,g1);fc.commit();}@Overridepublic void onClick(View v){FragmentManager FragmentManager = getFragmentManager();FragmentTransaction fTransaction = FragmentManager.beginTransaction();switch(v.getId()){case R.id.first:if(g1!=null){g1 = new MyFragment();g1.setContent("This is second fragment!");fTransaction.replace(R.id.activity_main,g1);fTransaction.commit();}}}@Overridepublic boolean onKeyDown(int keyCode, KeyEvent event) {if(keyCode == KeyEvent.KEYCODE_BACK && event.getAction() == KeyEvent.ACTION_DOWN){FragmentManager manager = getFragmentManager();FragmentTransaction transaction = manager.beginTransaction();g1 = new MyFragment();transaction.replace(R.id.activity_main,g1);transaction.commit();}return super.onKeyDown(keyCode, event);}
}

fragment代码

public class MyFragment extends Fragment {private String content;public MyFragment() {String s = "This is first fragment!";content = s;}public void setContent(String content){this.content = content;}@Overridepublic View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {View view = inflater.inflate(R.layout.fragment_my, container, false);TextView show = (TextView)view.findViewById(R.id.txt_show);show.setText(content);return view;}
}

实现图：