Question

我的应用程序有一个包含多个项目的listView和一个带有customAdapter的editText。为给定的文本过滤我的项目完全可以，但是当我尝试从已过滤的ist“打开”项目（通过将其传递到新的Intent）时，getItemAtPosition(position)从列表中返回给定位置的项目。原始列表，但不是来自过滤的列表。如何更改代码以将项目退回到已过滤列表的确切位置？

MainActivity.java

package fasde.android.distanceapp.View;

import android.content.Intent;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.View;
import android.widget.AdapterView;
import android.widget.EditText;
import android.widget.ListView;

import androidx.appcompat.app.AppCompatActivity;

import org.jetbrains.annotations.NotNull;

import java.util.ArrayList;
import java.util.Map;
import java.util.TreeMap;

import fasde.android.distanceapp.Controller.SpielortAdapter;
import fasde.android.distanceapp.DataBase.SaveData;
import fasde.android.distanceapp.Model.Spielort;
import fasde.android.distanceapp.R;
import lombok.NonNull;

/**
 * Creates a Activity about a ListView of Spielorts.
 */
public class MainActivity extends AppCompatActivity {

    ListView listView;
    SpielortAdapter spielortAdapter;
    EditText editText;

    /**
     * Gets the whole app running. Creates a listView, an editText and a spielortAdapter and gets
     * all of them running.
     *
     * @param savedInstanceState
     */
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Intent intent = getIntent();
        @NotNull
        String variante = intent.getStringExtra("variante");

        listView = findViewById(R.id.list);
        editText = findViewById(R.id.inputSearch);

        ArrayList<Spielort> spielorts = new ArrayList<>();

        Map<String, Spielort> vereine = new TreeMap<>();
        vereine.putAll(SaveData.fillVereine(variante));

        for (Map.Entry<String, Spielort> entry : vereine.entrySet()) {
            spielorts.add(entry.getValue());
        }

        spielortAdapter = new SpielortAdapter(this, spielorts);
        listView.setAdapter(spielortAdapter);

        editText.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
                // Nothing
            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                MainActivity.this.spielortAdapter.getFilter().filter(s);
            }

            @Override
            public void afterTextChanged(Editable s) {
                // Nothing
            }
        });

        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                Intent openDetail = new Intent(MainActivity.this, SpielortDetailActivity.class)
                        .putExtra("spielort", ((Spielort) listView.getItemAtPosition(position)).toStringArray());
                startActivity(openDetail);
            }
        });
    }
}

SpielortAdapter.java

package fasde.android.distanceapp.Controller;

import android.annotation.SuppressLint;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.Filter;
import android.widget.TextView;

import androidx.annotation.LayoutRes;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;

import org.jetbrains.annotations.NotNull;

import java.util.ArrayList;
import java.util.List;

import fasde.android.distanceapp.Model.Spielort;
import fasde.android.distanceapp.R;

/**
 * Custom Adapter for a ListView of Spielorts.
 */
public class SpielortAdapter extends ArrayAdapter<Spielort> {

    private Context context;
    private List<Spielort> spielortList;
    private List<Spielort> filteredList;
    private List<Spielort> allDataList;
    private SpielortFilter filter;

    /**
     * Constructor for SpielortAdapter, that creates an instance of this class while giving a
     * context and an ArrayList<Spielort>, that is used to initalize two beforehandly declared
     * Lists.
     *
     * @param context
     * @param spielortList
     */
    public SpielortAdapter(@NonNull Context context, @SuppressLint("SupportAnnotationUsage") @LayoutRes ArrayList<Spielort> spielortList) {
        super(context, 0, spielortList);
        this.context = context;
        this.spielortList = spielortList;
        this.allDataList = spielortList;
    }

    /**
     * Returns the size of the spielortList used at the moment.
     *
     * @return int
     */
    @Override
    public int getCount() {
        return spielortList.size();
    }

    /**
     * Returns an View-element which is used in the ListView. This element contains a Spielort.
     *
     * @param position
     * @param convertView
     * @param parent
     * @return View
     */
    @NonNull
    @Override
    public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
        View listItem = convertView;
        if (listItem == null) {
            listItem = LayoutInflater.from(context).inflate(R.layout.list_item, parent, false);
        }
        Spielort ort = spielortList.get(position);

        TextView spielort = listItem.findViewById(R.id.textView_ort);
        spielort.setText("\t" + ort.getSpielort());

        TextView km = listItem.findViewById(R.id.textView_km);
        km.setText(ort.getDistanz() + "km");

        TextView kosten = listItem.findViewById(R.id.textView_kosten);
        kosten.setText(ort.getKosten().toString() + "€");

        TextView kreis = listItem.findViewById(R.id.textView_kreis);
        kreis.setText(ort.getKreis().getName());

        return listItem;
    }

    /**
     * Returns the current Filter. If it is null, a new one is initialized.
     *
     * @return Filter
     */
    @Override
    public Filter getFilter() {
        if (filter == null) {
            filter = new SpielortFilter();
        }
        return filter;
    }

    private class SpielortFilter extends Filter {

        /**
         * Filters the Spielorts in the spielortList. Every Spielort, which name contains the
         * constraint, is returned.
         *
         * @param constraint
         * @return FilterResults
         */
        @Override
        protected FilterResults performFiltering(CharSequence constraint) {
            FilterResults results = new FilterResults();
            filteredList = new ArrayList<>();
            for (Spielort ort : allDataList) {
                if (ort.getSpielort().toLowerCase().contains(constraint.toString().toLowerCase())) {
                    filteredList.add(ort);
                }
            }
            results.count = filteredList.size();
            results.values = filteredList;
            return results;
        }

        /**
         * Publishes the results of the filtering to the listView.
         *
         * @param constraint
         * @param results
         */
        @SuppressWarnings("unchecked")
        @Override
        protected void publishResults(CharSequence constraint, @NotNull FilterResults results) {
            spielortList = (ArrayList<Spielort>) results.values;
            notifyDataSetChanged();
        }
    }


}

Answer 1

调用ListView.getItemAtPosition()方法时，它将调用Adapter.getItem()方法并返回结果。解决问题的最简单方法是在Adapter.getItem()类中重载SpielortAdapter方法，例如波纹管：

@Override
public Spielort getItem(int position) {
    return spielortList.get(position);
}

Answer 2

在SpielortAdapter类中为spielortList创建getter方法并以这种方式使用

//在适配器类中

public List<Spielort> getList(){
    return spielortList; 
}

//在活动课程中

listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                Intent openDetail = new Intent(MainActivity.this, SpielortDetailActivity.class)
                        .putExtra("spielort", (spielortAdapter .getList().get(position)).toStringArray());
                startActivity(openDetail);
            }
        });

Answer 3

您应该直接从适配器获得物品。将以下方法添加到您的SpielortAdapter中：

public Model getItemAtPosition(int position)
{
    return spielortList.get(position);
}

并从您的OnItemClickListener实现中调用它：

 spielortAdapter.getItemAtPosition(position)

带有FIlter的Android ListView：“打开”已过滤列表的项目将返回此位置的项目，但在原始列表中

3 个答案: