Android Studio 中 ListView 中的适配器

Question

我正在尝试通过三个类来补充控制自定义 ListView 的代码：AdapterListView、ItemListView 和 MainActivity。

到目前为止，代码仅设法通过AdapterListView 输入数据和图像（由代码插入）。在该类中，想知道如何使用其他功能，例如应用程序添加或删除项目。

以下三个项目类：

AdapterListView

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import java.util.ArrayList;

/**
* Created by LuizHMU on 2/7/15.
*/
public class AdapterListView extends BaseAdapter {

private LayoutInflater mInflater;
private ArrayList<ItemListView> itens;

public AdapterListView(Context context, ArrayList<ItemListView> itens) {
    //Itens que preencheram o listview
    this.itens = itens;
    //responsavel por pegar o Layout do item.
    mInflater = LayoutInflater.from(context);
}

/**
 * Retorna a quantidade de itens
 *
 * @return
 */
public int getCount() {
    return itens.size();
}

/**
 * Retorna o item de acordo com a posicao dele na tela.
 *
 * @param position
 * @return
 */
public ItemListView getItem(int position) {
    return itens.get(position);
}

/**
 * Sem implementação
 *
 * @param position
 * @return
 */
public long getItemId(int position) {
    return position;
}

public View getView(int position, View view, ViewGroup parent) {
    //Pega o item de acordo com a posção.
    ItemListView item = itens.get(position);
    //infla o layout para podermos preencher os dados
    view = mInflater.inflate(R.layout.item_list, null);

    //atravez do layout pego pelo LayoutInflater, pegamos cada id relacionado
    //ao item e definimos as informações.
    ((TextView) view.findViewById(R.id.text)).setText(item.getTexto());
    ((ImageView) view.findViewById(R.id.imagemview)).setImageResource(item.getIconeRid());

    return view;
}
}

ItemListView

/**
* Created by LuizHMU on 2/7/15.
*/
public class ItemListView {

private String texto;
private int iconeRid;

public ItemListView() {
}

public ItemListView(String texto, int iconeRid) {
    this.texto = texto;
    this.iconeRid = iconeRid;
}

public int getIconeRid() {
    return iconeRid;
}

public void setIconeRid(int iconeRid) {
    this.iconeRid = iconeRid;
}

public String getTexto() {
    return texto;
}

public void setTexto(String texto) {
    this.texto = texto;
}
}

MainActivity

import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;
import android.widget.Toast;

import java.util.ArrayList;

public class MainActivity extends Activity implements OnItemClickListener {

private ListView listView;
private AdapterListView adapterListView;
private ArrayList<ItemListView> itens;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    //carrega o layout onde contem o ListView
    setContentView(R.layout.activity_main);

    //Pega a referencia do ListView
    listView = (ListView) findViewById(R.id.list);
    //Define o Listener quando alguem clicar no item.
    listView.setOnItemClickListener(this);

    createListView();
}

private void createListView() {
    //Criamos nossa lista que preenchera o ListView
    itens = new ArrayList<ItemListView>();
    ItemListView item1 = new ItemListView("Felpudo", R.drawable.felpudo);
    ItemListView item2 = new ItemListView("Felpudão", R.drawable.felpudo1);
    ItemListView item3 = new ItemListView("Felpudinho", R.drawable.felpudo2);

    itens.add(item1);
    itens.add(item2);
    itens.add(item3);

    //Cria o adapter
    adapterListView = new AdapterListView(this, itens);

    //Define o Adapter
    listView.setAdapter(adapterListView);
    //Cor quando a lista é selecionada para ralagem.
    listView.setCacheColorHint(Color.TRANSPARENT);
}

public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
    //Pega o item que foi selecionado.
    ItemListView item = adapterListView.getItem(arg2);
    //Demostração
    Toast.makeText(this, "Você Clicou em: " + item.getTexto(), Toast.LENGTH_LONG).show();
}
}

Answer 1

将此添加到您的适配器：

public void addItem(ItemListView item){
 items.add(item);
 notifyDatasetChanged();
}

public void removeItem(int positionToRemove){
 items.remove(positionToRemove);
 notifyDatasetChanged();
}

为了进一步解释发生了什么，适配器是控制器，是信息和在视图中显示信息的方式（ListView）之间的中间步骤。这种情况下的信息是通过 items 列表提供给适配器的，所以基本上操作列表并调用 notifyDataSetChanged() 会改变显示给用户的视图。

希望我能有所帮助。

Answer 2

您可以在活动中使用这样的简单方法：

private void addItemToList(ItemListView item){
    if(item != null){
       itens.add(item) 
    }
}

（删除单元格使用 list.remove()）

在你的适配器中添加这个：

public void loadNewList(List<ItemListView> list){
    if(itens != null){
        itens.clear;
    }
    itens = list;
    notifyDataSetChanged();
}

nb : 你应该对列表单元格使用持有者模式:)

Answer 3

在您的活动中，您有listView 属性。在onCreate() 方法中，您可以这样做：

listView.setOnItemLongClickListener(new OnItemLongClickListener() {
            public boolean onItemLongClick(AdapterView<?> parent, View view,
                    int position, long id) {
                final ItemListView item = (ItemListView) parent.getItemAtPosition(position);
                // Do whatever you want here !!
                adapterListView.notifyDataSetChanged();
                return true;
            }
        });