如何使用 BaseAdapter 在自定义 ListView 中进行过滤

Question

我似乎找不到如何使我的自定义 getFilter() 工作。 我的CustomAdapter 扩展了BaseAdapter，据我所知，它没有实现过滤，所以我需要自己做。我尝试了各种方法，但都没有成功。

Q1：方法是什么？ （如何正确实现过滤？）

Q2：如何更改我的CustomAdapter(!) 以使过滤成为一项自动功能？

请不要忽视！ 提前非常感谢！

这是一段代码：

Main.java

    //  import ....

    public class MainActivity extends Activity  {

    ListView lv;
    Context context;
    EditText et;
    CustomAdapter adapter;
    View v;

    public  int [] Images=   {R.drawable.1,R.drawable.2,R.drawable.3,R.drawable.4};
    public  String [] NameList={"item1","item2","item3","item4"};

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

        context=this;

        lv=(ListView) findViewById(R.id.listView);
        adapter = new CustomAdapter(this, fruitNameList,fruitImages);
        lv.setAdapter(adapter);

        et = (EditText)findViewById(R.id.editText);

        /**
         * Enabling Search Filter
         * */
        et.addTextChangedListener(new TextWatcher() {

            @Override
            public void onTextChanged(CharSequence cs, int arg1, int arg2, int arg3) {
                // When user changed the Text
                MainActivity.this.adapter.getFilter().filter(cs); // !!!!getFilter() is not found I tried to write methods on my own but nothing worked
            }

            @Override
            public void beforeTextChanged(CharSequence arg0, int arg1, int arg2,
                                          int arg3) {
                // TODO Auto-generated method stub

            }

            @Override
            public void afterTextChanged(Editable arg0) {
                // TODO Auto-generated method stub
            }
        });



   }// end of onCreate

    public void onClick (View v) {
        switch (v.getId()) {
            case R.id.search:
                et.setVisibility(v.VISIBLE);
                et.setHint("Search names...");

                break;
        }
    }

    public void SearchFilterEnable() {
        /**
         * Enabling Search Filter
         * */
        et.addTextChangedListener(new TextWatcher() {

            @Override
            public void onTextChanged(CharSequence cs, int arg1, int arg2, int arg3) {
                // When user changed the Text
                MainActivity.this.adapter.getFilter().filter(cs);
            }

            @Override
            public void beforeTextChanged(CharSequence arg0, int arg1, int arg2,
                                          int arg3) {
                // TODO Auto-generated method stub

            }

            @Override
            public void afterTextChanged(Editable arg0) {
                // TODO Auto-generated method stub
            }
        });

    }
}

CustomAdapter.java

  //import...

  public class CustomAdapter extends BaseAdapter implements Filterable{
  String [] result;
  Context context;
  int [] imageId;
  private static LayoutInflater inflater=null;
  public CustomAdapter(MainActivity mainActivity, String[] NameList, int[] Images) {
    result=NameList;
    context=mainActivity;
    imageId=Images;
    inflater = ( LayoutInflater )context.
            getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
@Override
public int getCount() {
    return result.length;
}

@Override
public Object getItem(int position) {
    return position;
}

@Override
public long getItemId(int position) {
   return position;
}

public class Holder
{
    TextView tv;
    ImageView img;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
    Holder holder=new Holder();
    View v;
    v = inflater.inflate(R.layout.name_list, null);
    holder.tv=(TextView) v.findViewById(R.id.textView1);
    holder.img=(ImageView) v.findViewById(R.id.imageView1);
    holder.tv.setText('\t'+result[position]);
    holder.img.setImageResource(imageId[position]);
    v.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            Toast.makeText(context, "You Clicked " + result[position], Toast.LENGTH_LONG).show();
        }
    });

         return v;
    }



}

Answer 1

一种方法是更改​​适配器的底层数据（也就是过滤数据），然后在适配器上调用notifyDataSetChanged();。如果您这样做，您的 ListView 将被告知数据集已更改并将更新其内容。

您应该在适配器中存储两个数据列表，一个包含原始数据的列表，一个包含过滤数据的列表。适配器本身对过滤后的列表进行操作，每当您调用过滤器方法时，它只会将原始列表中的数据复制到过滤后的列表中（基于您的过滤条件）。

private List<String> originalData;
private List<String> filteredData;

public void filter(String prefix) {
    filteredData = new ArrayList<>();
    for(String data : originalData) {
        if(data.startsWith(prefix)) filteredData.add(data);
    }
    notifyDataSetChanged();
}