Question

我有一个带有自定义ListView的{{1}}，其中包含一个UserAdapter和当前激活（选定）的ID。

方法SparseBooleanArray从我的toggleSelection(position)中创建或删除一个条目。因此，我有可能在SparseBooleanArray中的DriverFragment中的listView.onItemClickListener()中调用此方法，因此，该项目的背景可绘制对象在单击时会发生变化。

现在，我想以编程方式在 DriverSelectionFragment 中预先选择一项。 到目前为止，我可以将其添加到我的SparseBooleanArray中，但输入片段时背景不会改变。

我想念什么？我是否需要通知listView？我在onViewCreated()中添加了所选项目，因此它应该可以工作。

编辑：添加了xml文件

UserAdapter：

package com.example.convictedDriver.Adapters;

import android.content.Context;
import android.util.Log;
import android.util.SparseBooleanArray;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import com.example.convictedDriver.Database.User;
import com.example.convictedDriver.R;
import com.mikhaellopez.circularimageview.CircularImageView;

import org.jetbrains.annotations.NotNull;

import java.util.List;

public class UserAdapter extends ArrayAdapter<User> {
    // Declare Variables
    private List<User> userList;
    private ViewGroup parent;
    private LayoutInflater inflater;
    private SparseBooleanArray mSelectedItemsIds;

    public UserAdapter(Context context, int resource, List<User> userList) {
        super(context, resource, userList);
        mSelectedItemsIds = new SparseBooleanArray();
        this.userList = userList;
        inflater = LayoutInflater.from(context);
    }

    private class ViewHolder {
        TextView name;
        TextView ratio;
        CircularImageView circularImageView;
    }

    @Override
    public View getView(int position, View view, @NotNull ViewGroup parent) {
        final ViewHolder holder;
        this.parent = parent;
        if(view == null){
            holder = new ViewHolder();
            view = inflater.inflate(R.layout.list_item, null, false);
            // Locate the TextViews and Imageview in list_item.xml
            holder.name = view.findViewById(R.id.user_name_text);
            holder.ratio = view.findViewById(R.id.user_ratio_text);
            holder.circularImageView = view.findViewById(R.id.list_item_imageView);
            view.setTag(holder);
        }else{
            holder = (ViewHolder) view.getTag();
        }
        // Capture position and set to the TextViews and ImageView
        holder.name.setText(userList.get(position).getUsername());
        holder.ratio.setText(String.valueOf((userList.get(position).getRatio())));
        holder.circularImageView.setScaleType(ImageView.ScaleType.FIT_CENTER);
        return view;
    }

    @Override
    public void remove(User user){
        userList.remove(user);
        notifyDataSetChanged();
    }

    public List<User> getUserList(){
        return userList;
    }

    // Toggles the selection state of a given item position
    public void toggleSelection(int position) {
        selectView(position, !mSelectedItemsIds.get(position));
        Log.i("Debug", "Position "+position+" changed state from "+!mSelectedItemsIds.get(position)+" to "+
                mSelectedItemsIds.get(position));
    }

    // Removes all selections
    public void removeSelection() {
        mSelectedItemsIds = new SparseBooleanArray();
        notifyDataSetChanged();
    }

    // Helper Class for toggling a specific item position
    private void selectView(int position, boolean value) {
        if (value) {
            mSelectedItemsIds.put(position, value);
        }
        else {
            mSelectedItemsIds.delete(position);
        }
    }

    // Returns the amount of selected items
    public int getCheckedCount() {
        int num = 0;
        for (int i = 0; i < mSelectedItemsIds.size(); i++) {
            if (mSelectedItemsIds.valueAt(i)) {
                num++;
            }
        }
        return num;
    }

    // Returns the SparseBooleanArray for the ListView
    public SparseBooleanArray getSelectedIds() {
        return mSelectedItemsIds;
    }

}

DriverFragment：

package com.example.convictedDriver.Fragments.Drive;

import android.os.Bundle;
import android.util.Log;
import android.util.SparseBooleanArray;
import android.view.ActionMode;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.AdapterView;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.core.content.ContextCompat;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentTransaction;
import androidx.navigation.Navigation;

import com.example.convictedDriver.Adapters.UserAdapter;
import com.example.convictedDriver.Classes.MyListSorter;
import com.example.convictedDriver.Classes.MyToast;
import com.example.convictedDriver.Database.IntegratedDatabase.UserDbHelper;
import com.example.convictedDriver.Database.User;
import com.example.convictedDriver.R;
import com.google.android.material.floatingactionbutton.FloatingActionButton;

import java.util.ArrayList;

public class DriveFragment extends Fragment {

    private FloatingActionButton fabContinue;
    private ArrayList<User> userList;
    private ListView listView;
    private UserAdapter adapter;
    private SparseBooleanArray checked;

    public DriveFragment() {
        // Required empty public constructor
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_drive, container, false);

        // Getting all the users out of the database and sort them
        UserDbHelper db = UserDbHelper.getInstance(getContext());
        userList = db.getAllUsers();
        MyListSorter.sort(userList, MyListSorter.SortType.RATIO);

        // Locate the ListView and in fragment_drive.xml
        listView = view.findViewById(R.id.drive_listView);
        fabContinue = view.findViewById(R.id.fab_continue);
        return view;
    }

    @Override
    public void onResume() {
        super.onResume();

    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable final Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        // Pass userList to UserAdapter Class
        adapter = new UserAdapter(getContext(), R.layout.list_item, userList);
        // Binds the Adapter to the ListView
        listView.setItemsCanFocus(false);
        listView.setAdapter(adapter);

        checked = adapter.getSelectedIds();
        Toast.makeText(getContext(), "OnViewCreated: "+checked.toString(),Toast.LENGTH_SHORT).show();

        // Capture ListView item click
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                // Toggle the ListViewItems State
                adapter.toggleSelection(position);
                Toast.makeText(getContext(), "OnItemClick: "+checked.toString(),Toast.LENGTH_SHORT).show();
            }
        });

        /*
        * Create an array out of the selectedUsers Arraylist and pass it
        * towards DriveSelectionFragment
         */
        fabContinue.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v) {
                checked = adapter.getSelectedIds();
                Toast.makeText(getContext(), "OnClickListener: "+checked.toString(),Toast.LENGTH_SHORT).show();
                if(adapter.getCheckedCount() > 2) {
                    User[] userArray = new User[checked.size()];
                    int j = 0;
                    for (int i = (checked.size() - 1); i >= 0; i--){
                        if (checked.valueAt(i)){
                            userArray[j] = adapter.getItem(checked.keyAt(i));
                            j++;
                        }
                    }
                    //listView.clearChoices();
                    adapter.removeSelection();
                    DriveFragmentDirections.ActionDriveFragmentToDriveSelectionFragment action =
                            DriveFragmentDirections.actionDriveFragmentToDriveSelectionFragment(userArray);
                    Navigation.findNavController(v).navigate(action);
                }else{
                    new MyToast(getContext(), "Select at least 3 Users!", Toast.LENGTH_SHORT).show();
                }
            }
        });
    }
}

DriverSelectionFragment：

package com.example.convictedDriver.Fragments.Drive;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;

import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.util.SparseBooleanArray;
import android.view.LayoutInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.Toast;

import com.example.convictedDriver.Adapters.UserAdapter;
import com.example.convictedDriver.Database.User;
import com.example.convictedDriver.R;

import java.io.File;
import java.util.ArrayList;

public class DriveSelectionFragment extends Fragment {

    private ArrayList<User> selectedDrivers = new ArrayList<>();
    private ArrayList<User> userList = new ArrayList<>();
    private ListView listView;
    private UserAdapter adapter;
    private User driver;
    private View view;
    private SparseBooleanArray checked;

    public DriveSelectionFragment(){
        // Empty constructor is needed
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        view = inflater.inflate(R.layout.fragment_drive_selection, container, false);
        listView = view.findViewById(R.id.driveSelection_listView);
        return view;
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        // Receive an ArrayList as argument, including all the userList
        if(getArguments() != null){
            DriveSelectionFragmentArgs args = DriveSelectionFragmentArgs.fromBundle(getArguments());
            userList = arrayToList(args.getSelectedUsers());
        }

        // Calculate the user with the highest ratio out of the userList
        // and add it to the selectedDrivers ArrayList
        driver = calculateDriver(userList);
        selectedDrivers.add(driver);
        Toast.makeText(getContext(), "Driver: "+driver.getUsername(),Toast.LENGTH_SHORT).show();

        // Initialize listView and set the adapter
        adapter = new UserAdapter(getContext(),R.layout.list_item, userList);
        listView.setItemsCanFocus(false);


        int driverPos = getDriverPosition(userList, driver);
        Toast.makeText(getContext(), "DriverPosition: "+driverPos,Toast.LENGTH_SHORT).show();
        adapter.toggleSelection(getDriverPosition(userList,driver));

        checked = adapter.getSelectedIds();
        Toast.makeText(getContext(), "OnViewCreated: "+checked.toString(),Toast.LENGTH_SHORT).show();

        // Binds the Adapter to the ListView
        listView.setAdapter(adapter);

        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                // Toggle the ListViewItems State
                adapter.toggleSelection(position);
                Toast.makeText(getContext(), "OnItemClick: "+checked.toString(),Toast.LENGTH_SHORT).show();
            }
        });

    }


    /*
    *
    * Calculates a user out of a given list with the highest ratio
    *
     */
    private User calculateDriver(ArrayList<User> list){
        User currUser = list.get(0);
        for (User user : list){
            if(user.getRatio() >= currUser.getRatio()){
                Log.i("Test", user.getRatio() +">"+ currUser.getRatio());
                currUser = user;
                Log.i("Test", "Changed driver to "+currUser);
            }
        }
        return currUser;
    }

    private int getDriverPosition(ArrayList<User> list, User driver){
        int position = 0;
        for (User user: list) {
            if (user.getId() == driver.getId()){
                return position;
            }else{
                position++;
            }
        }
        return -1;
    }

fragment_drive_selection.xml文件：

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".Fragments.Drive.DriveSelectionFragment">

    <ListView
        android:id="@+id/driveSelection_listView"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:divider="@null"
        android:dividerHeight="3dp"
        android:layout_marginVertical="5dp"
        android:choiceMode="multipleChoice"
        android:listSelector="@android:color/transparent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"/>

</androidx.constraintlayout.widget.ConstraintLayout>

list_item.xml文件：

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:foreground="?attr/selectableItemBackground"
    android:background="@drawable/list_item_selector">

    <com.mikhaellopez.circularimageview.CircularImageView
        android:id="@+id/list_item_imageView"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:layout_marginStart="5dp"
        android:layout_marginTop="5dp"
        android:layout_marginBottom="5dp"
        app:civ_border="false"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        android:src="@drawable/avatar_1"/>

    <TextView
        android:id="@+id/user_name_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="8dp"
        android:layout_marginStart="8dp"
        android:autoSizeTextType="uniform"
        android:text=""
        android:textColor="@color/colorSpotifyWhite"
        android:textSize="22sp"
        app:layout_constraintBottom_toTopOf="@+id/user_ratio_text"
        app:layout_constraintStart_toEndOf="@+id/list_item_imageView"
        app:layout_constraintTop_toTopOf="parent"
        tools:text="name" />

    <TextView
        android:id="@+id/user_ratio_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:layout_marginStart="8dp"
        android:text=""
        tools:text="ratio"
        android:textSize="16sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toEndOf="@id/list_item_imageView"
        app:layout_constraintTop_toBottomOf="@id/user_name_text" />

</androidx.constraintlayout.widget.ConstraintLayout>

list_item_selector.xml文件：

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android" >
    <!-- pressed -->
    <item android:state_enabled="true"
        android:state_pressed="true" android:drawable="@drawable/list_item_background_selected" />
    <!-- focused -->
    <item android:state_enabled="true"
        android:state_focused="true" android:drawable="@drawable/list_item_background_selected" />
    <!-- selected -->
    <item android:state_enabled="true"
        android:state_selected="true" android:drawable="@drawable/list_item_background_selected" />
    <!-- default -->
    <item android:state_enabled="true"
        android:state_checked="true" android:drawable="@drawable/list_item_background_selected" />

    <item android:state_activated="true"
        android:drawable="@drawable/list_item_background_selected" />

    <!-- default -->
    <item android:drawable="@drawable/list_item_background" />
</selector>

Answer 1

设置多选模式时，您必须在ListView上使用setItemChecked来选择项目。检查以下内容：

int selctedPosition = getDriverPosition(userList,driver);
adapter.toggleSelection(selctedPosition);

// Binds the Adapter to the ListView
listView.setAdapter(adapter);
listView.setItemChecked(selctedPosition, true);

将ListView项目的状态更改为以编程方式激活？

1 个答案: