android - android.support.v7 中的片段

Question

我是 android 新手，我试图在 android support v7 库中创建一个片段，当我想从片段类创建一个对象并使用我的片段 java 新建它时，它发生了一个无法编译类型的错误。

主要活动

public class MainActivity extends AppCompatActivity {

    private TextView mTextMessage;

    private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
            = new BottomNavigationView.OnNavigationItemSelectedListener() {

        @Override
        public boolean onNavigationItemSelected(@NonNull MenuItem item) {
            switch (item.getItemId()) {
                case R.id.navigation_home:
                    mTextMessage.setText(R.string.title_home);
                    return true;
                case R.id.navigation_dashboard:
                    mTextMessage.setText(R.string.title_dashboard);
                    return true;
                case R.id.navigation_notifications:
                    mTextMessage.setText(R.string.title_notifications);
                    return true;
            }
            return false;
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mTextMessage = (TextView) findViewById(R.id.message);
        BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
        navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
    }

    public boolean test(){
        Fragment fr =  new navigation_page1();
        FragmentManager fm = getFragmentManager();
        FragmentTransaction ft = fm.beginTransaction();
        ft.replace(R.id.fragment_page1,fr);
    }

}

错误在这一行

Fragment fr = new navigation_page1();

并且navigation_page1是在我的主布局中使用片段标记初始化的片段 java 代码。

我的 main_xml 代码：

        <?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:id="@+id/container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">
    <fragment
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:name="com.example.aqamamad.myapplication.navigation_page1"
            android:id="@+id/fragment_page1"

    ></fragment>
    <android.support.design.widget.BottomNavigationView
            android:id="@+id/navigation"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_marginEnd="0dp"
            android:layout_marginStart="0dp"
            android:background="?android:attr/windowBackground"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:menu="@menu/navigation"/>
</android.support.constraint.ConstraintLayout>

我的 navigation_page1 代码：

   public class navigation_page1 extends Fragment {


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    return inflater.inflate(R.layout.fragment_navigation_page1, container, false);
}}

标签： androidandroid-fragments

Answer 1

问题解决了..

转到片段 java 类并删除这一行 --> import android.support.v4.app.Fragment;

而不是写这一行 --> import android.app.Fragment;