# 利用fragment實現界面跳轉

利用fragment實現界面跳轉

---

• 任務要求
  利用fragment實現界面跳轉功能，完成效果以下圖所示
  圖片1

個人想法是在xml文件裏設置Button。再建立一個fragment文件。在java文件中動態加載fragment完成第一張效果。點擊按鈕後在動態加載一張fragment實現setcontent方法改寫內容字符串。點擊返回鍵返回第一張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">

   <LinearLayout
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:orientation="horizontal"
       android:layout_alignParentBottom="true">
       <Button
           android: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 -->
    <TextView
        android: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代碼
activity

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private MyFragment g1;
    private Button first;

    @Override
    protected 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();

    }

    @Override
    public 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();
                }
        }
    }

    @Override
    public 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代碼

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;
    }

    @Override
    public 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;
    }
}

實現圖：