Question

所以我正在开发一个应用程序，它使用firebase来加载总线列表，如果它们已经到达。我对此比较陌生，并试图使用片段。我可以使用总线列表成功加载片段，但是当我滚动它们时，它会留下项目的副本，如下所示：

MainActivity：

public class MainActivity extends AppCompatActivity {

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

    setTitle(null);

    Toolbar myToolbar = (Toolbar) findViewById(R.id.my_toolbar);
    setSupportActionBar(myToolbar);

    FragmentManager manager = getSupportFragmentManager();
    FragmentTransaction transaction = manager.beginTransaction();

    BusFragment busFragment = new BusFragment();
    transaction.add(R.id.buscontainer, busFragment);
    transaction.commit();

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;

}

MainActivity xml：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context="com.jackheinemann.schoolbus.MainActivity">

    <android.support.v7.widget.Toolbar
        android:id="@+id/my_toolbar"
        android:minHeight="?attr/actionBarSize"
        android:background="@color/colorPrimary"
        android:layout_width="match_parent"
        android:layout_height="64dp"/>

    <FrameLayout
        android:id="@+id/buscontainer"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom">
    </FrameLayout>


</LinearLayout>

BusFragment：

    public class BusFragment extends Fragment {

    public boolean isInitialized = false;

    // Database Instance Variables
    private FirebaseDatabase mFirebaseDatabase;
    private DatabaseReference mBusref;
    private ChildEventListener mChildEventListener;

    // Tablerow ID's
    final Integer[] tableRows = {R.id.tablerow1, R.id.tablerow2, R.id.tablerow3,
            R.id.tablerow4, R.id.tablerow5, R.id.tablerow6, R.id.tablerow7, R.id.tablerow8,
            R.id.tablerow9, R.id.tablerow10, R.id.tablerow11, R.id.tablerow12,
            R.id.tablerow13, R.id.tablerow14, R.id.tablerow15};

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

    public void onSignedInInitialize() {
        if (mChildEventListener == null) {
            mFirebaseDatabase = FirebaseDatabase.getInstance();
            mBusref = mFirebaseDatabase.getReference().child("buses");

            mChildEventListener = new ChildEventListener() {
                @Override
                public void onChildAdded(DataSnapshot dataSnapshot, String s) {
                }

                @Override
                public void onChildChanged(DataSnapshot dataSnapshot, String s) {
                    String bus_name = dataSnapshot.getKey();
                    Boolean bus_loc = dataSnapshot.getValue(Boolean.class);
                    String bus_location = Boolean.toString(bus_loc);

                    Integer findview = grabBusNumber(bus_name);


                    TextView textView = (TextView) getView().findViewById(findview);
                    textView.setText(bus_location);
                }

                @Override
                public void onChildRemoved(DataSnapshot dataSnapshot) {
                }

                @Override
                public void onChildMoved(DataSnapshot dataSnapshot, String s) {
                }

                @Override
                public void onCancelled(DatabaseError databaseError) {
                }
            };
            mBusref.addChildEventListener(mChildEventListener);

        }
    }

    public void init() {
        mBusref.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                int i = 1;
                View view = getView();
                for (DataSnapshot buslist : dataSnapshot.getChildren()) {
                    if (i < 16) {
                        String bus = "Bus " + Integer.toString(i);
                        Boolean location = buslist.getValue(Boolean.class);

                        TextView bus_name = new TextView(getActivity());
                        TextView bus_location = new TextView(getActivity());

                        TableRow.LayoutParams params = new TableRow.LayoutParams(0, TableRow.LayoutParams.WRAP_CONTENT, 1f);

                        bus_name.setText(bus);
                        bus_name.setTextSize(30);
                        bus_name.setLayoutParams(params);
                        bus_name.setGravity(Gravity.CENTER);


                        bus_location.setText(Boolean.toString(location));
                        bus_location.setTextSize(30);
                        bus_location.setLayoutParams(params);
                        bus_location.setGravity(Gravity.CENTER);
                        Integer identifier = i;
                        bus_location.setId(identifier);

                        if (view != null) {
                            TableRow tableRow = (TableRow) view.findViewById(tableRows[i - 1]);
                            tableRow.addView(bus_name);
                            tableRow.addView(bus_location);
                            i++;
                        }
                    }
                }

            }

            @Override
            public void onCancelled(DatabaseError databaseError) {
            }
        });
        isInitialized = true;
    }

    private Integer grabBusNumber(String bus_id) {
        String string;
        if (bus_id.charAt(1) != '_') {
            string = Character.toString(bus_id.charAt(0)) + Character.toString(bus_id.charAt(1));
        } else {
            string = Character.toString(bus_id.charAt(0));
        }
        Integer integer = Integer.parseInt(string);
        return integer;
    }
}

activity_bus_fragment.xml：

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_bus_fragment"
    android:orientation="vertical"
    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.jackheinemann.schoolbus.BusFragment">

    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content">


            <TableLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent">

                <TableRow
                    android:id="@+id/tablerow1"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent" />

                <TableRow
                    android:id="@+id/tablerow2"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent" />

                <TableRow
                    android:id="@+id/tablerow3"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent" />

                <TableRow
                    android:id="@+id/tablerow4"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent" />

                <TableRow
                    android:id="@+id/tablerow5"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent" />

                <TableRow
                    android:id="@+id/tablerow6"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent" />

                <TableRow
                    android:id="@+id/tablerow7"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent" />

                <TableRow
                    android:id="@+id/tablerow8"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent" />

                <TableRow
                    android:id="@+id/tablerow9"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent" />

                <TableRow
                    android:id="@+id/tablerow10"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent" />

                <TableRow
                    android:id="@+id/tablerow11"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent" />

                <TableRow
                    android:id="@+id/tablerow12"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent" />

                <TableRow
                    android:id="@+id/tablerow13"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent" />

                <TableRow
                    android:id="@+id/tablerow14"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent" />

                <TableRow
                    android:id="@+id/tablerow15"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent" />
            </TableLayout>
    </ScrollView>




</LinearLayout>

Answer 1

对于寻找答案的任何人，我解决问题的方法是将片段添加更改为片段替换。由于某种原因，它是两次添加片段，因此＆＃34;阴影＆＃34;。替换而不是添加确保只有一个加载并修复了问题。

为什么我的滚动视图会离开＆＃34;阴影＆＃34;背后？

1 个答案: