自动完成文本框始终显示特定项

Question

我正在使用一个类似于以下示例的AutoCompleteTextView：

public class MainActivity extends Activity {

   private AutoCompleteTextView actv;
   private MultiAutoCompleteTextView mactv;

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


   String[] countries = getResources().
   getStringArray(R.array.list_of_countries);
   ArrayAdapter adapter = new ArrayAdapter
   (this,android.R.layout.simple_list_item_1,countries);


   actv = (AutoCompleteTextView) findViewById(R.id.autoCompleteTextView1);
   mactv = (MultiAutoCompleteTextView) findViewById
   (R.id.multiAutoCompleteTextView1);

   actv.setAdapter(adapter);
   mactv.setAdapter(adapter);

   mactv.setTokenizer(new MultiAutoCompleteTextView.CommaTokenizer());


   }

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

}

这可以完成大部分工作。但是，在我的情况下，我需要自动完成在返回的下拉建议底部显示类似“custom...”的内容。

所以，如果有自动完成建议，它们将显示为“custom...”建议之后。如果没有建议，它仍将显示一个建议“custom...”。我还需要一个“custom...”的点击监听器。

- harveyslash

---

使用自定义适配器，可以继承BaseAdapter，但如果我是你，我会使用SimpleCursorAdapter和MergeCursor。 - pskink

Answer 1

有趣的问题，我尝试实现了一个简单的自定义适配器，基于ArrayAdapter源代码。为了简洁起见，大部分未使用的代码和注释都被省略了，如果您不确定，请查看我上面链接的ArrayAdapter源代码，它有很好的注释。

操作原理非常简单，适配器的getCount()将实际元素数量加一。同时，getItem(int position)会检查是否请求了最后一个“虚拟”项目，并返回你的 “Custom…” 字符串。 createViewFromResource(...) 方法在显示最后一个“虚拟”项时也会检查，如果是，则绑定一个 onClick 监听器。

覆盖的 Filter 也会将结果计数加一，以使 AutoCompleteView 相信有匹配项，因此它保持下拉列表打开状态。 MainActivity.java

public class MainActivity extends ActionBarActivity {

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

        String[] countries  = new String[]{
                "Switzerland", "Mexico", "Poland", "United States of Murica"};

        // the footer item's text
        String   footerText = "Custom Footer....";

        // our custom adapter with the custom footer text as last parameter
        CustomAutoCompleteAdapter adapter = new CustomAutoCompleteAdapter(
                this, android.R.layout.simple_list_item_1, countries, footerText);

        // bind to our custom click listener interface
        adapter.setOnFooterClickListener(new CustomAutoCompleteAdapter.OnFooterClickListener() {
            @Override
            public void onFooterClicked() {
                // your custom item has been clicked, make some toast
                Toast toast = Toast.makeText(getApplicationContext(), "Yummy Toast!", Toast.LENGTH_LONG);
                toast.setGravity(Gravity.CENTER, 0, 0);
                toast.show();
            }
        });

        // find auto complete text view
        AutoCompleteTextView actv = (AutoCompleteTextView) findViewById(R.id.autoCompleteTextView1);
        actv.setThreshold(0);
        actv.setAdapter(adapter);
    }
}

CustomAutoCompleteAdapter.java

public class CustomAutoCompleteAdapter extends BaseAdapter implements Filterable {

    public interface OnFooterClickListener {
        public void onFooterClicked();
    }

    private List<String> mObjects;
    private final Object mLock = new Object();

    private int mResource;
    private int mDropDownResource;

    private ArrayList<String> mOriginalValues;
    private ArrayFilter mFilter;

    private LayoutInflater mInflater;

    // the last item, i.e the footer
    private String mFooterText;

    // our listener
    private OnFooterClickListener mListener;

    public CustomAutoCompleteAdapter(Context context, int resource, String[] objects, String footerText) {
        mInflater   = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        mResource   = mDropDownResource = resource;
        mObjects    = Arrays.asList(objects);
        mFooterText = footerText;
    }


    /**
     * Set listener for clicks on the footer item
     */
    public void setOnFooterClickListener(OnFooterClickListener listener) {
        mListener = listener;
    }

    @Override
    public int getCount() {
        return mObjects.size()+1;
    }

    @Override
    public String getItem(int position) {
        if(position == (getCount()-1)) {
            // last item is always the footer text
            return mFooterText;
        }

        // return real text
        return mObjects.get(position);
    }

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        return createViewFromResource(position, convertView, parent, mResource);
    }

    private View createViewFromResource(int position, View convertView, ViewGroup parent,
                                        int resource) {
        View view;
        TextView text;

        if (convertView == null) {
            view = mInflater.inflate(resource, parent, false);
        } else {
            view = convertView;
        }

        try {
            //  If no custom field is assigned, assume the whole resource is a TextView
            text = (TextView) view;
        } catch (ClassCastException e) {
            Log.e("CustomAutoCompleteAdapter", "Layout XML file is not a text field");
            throw new IllegalStateException("Layout XML file is not a text field", e);
        }

        text.setText(getItem(position));

        if(position == (getCount()-1)) {
            // it's the last item, bind click listener
            view.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    if(mListener != null) {
                        mListener.onFooterClicked();
                    }
                }
            });
        } else {
            // it's a real item, set click listener to null and reset to original state
            view.setOnClickListener(null);
            view.setClickable(false);
        }

        return view;
    }

    @Override
    public View getDropDownView(int position, View convertView, ViewGroup parent) {
        return createViewFromResource(position, convertView, parent, mDropDownResource);
    }

    @Override
    public Filter getFilter() {
        if (mFilter == null) {
            mFilter = new ArrayFilter();
        }
        return mFilter;
    }

    /**
     * <p>An array filter constrains the content of the array adapter with
     * a prefix. Each item that does not start with the supplied prefix
     * is removed from the list.</p>
     */
    private class ArrayFilter extends Filter {
        @Override
        protected FilterResults performFiltering(CharSequence prefix) {
            FilterResults results = new FilterResults();

            if (mOriginalValues == null) {
                synchronized (mLock) {
                    mOriginalValues = new ArrayList<String>(mObjects);
                }
            }

            if (prefix == null || prefix.length() == 0) {
                ArrayList<String> list;
                synchronized (mLock) {
                    list = new ArrayList<String>(mOriginalValues);
                }
                results.values = list;

                // add +1 since we have a footer item which is always visible
                results.count = list.size()+1;
            } else {
                String prefixString = prefix.toString().toLowerCase();

                ArrayList<String> values;
                synchronized (mLock) {
                    values = new ArrayList<String>(mOriginalValues);
                }

                final int count = values.size();
                final ArrayList<String> newValues = new ArrayList<String>();

                for (int i = 0; i < count; i++) {
                    final String value = values.get(i);
                    final String valueText = value.toString().toLowerCase();

                    // First match against the whole, non-splitted value
                    if (valueText.startsWith(prefixString)) {
                        newValues.add(value);
                    } else {
                        final String[] words = valueText.split(" ");
                        final int wordCount = words.length;

                        // Start at index 0, in case valueText starts with space(s)
                        for (int k = 0; k < wordCount; k++) {
                            if (words[k].startsWith(prefixString)) {
                                newValues.add(value);
                                break;
                            }
                        }
                    }
                }

                results.values = newValues;
                // add one since we always show the footer
                results.count = newValues.size()+1;
            }

            return results;
        }

        @Override
        protected void publishResults(CharSequence constraint, FilterResults results) {
            //noinspection unchecked
            mObjects = (List<String>) results.values;
            notifyDataSetChanged();
        }
    }
}

layout/activity_main.xml

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"   
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="20dp"
    tools:context=".MainActivity">

    <AutoCompleteTextView
        android:id="@+id/autoCompleteTextView1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

</LinearLayout>

- sled

---

干得好，我认为if (valueText.contains(prefixString)) {会比if (valueText.startsWith(prefixString)) {更好。(y) - shafeeq

Answer 2

谢谢@sled，你的回答很好。我已经通过一些修改将其转换为Kotlin。

class CustomAutoCompleteAdapter<T>(
    var context: Context,
    private var resource: Int,
    var objects: ArrayList<T>,
    private var footerText: String
): BaseAdapter(), Filterable {
    private var footerClickListener: OnFooterClickListener? = null
    private var filter =  ArrayFilter()

    interface OnFooterClickListener {
        fun onFooterClick()
    }

    fun setOnFooterClickListener(listener: OnFooterClickListener) {
        footerClickListener = listener
    }

    override fun getCount() = objects.size + 1

    override fun getItem(position: Int) = if(position <= objects.size - 1) objects[position].toString() else footerText

    override fun getItemId(position: Int) = position.toLong()

    override fun getView(position: Int, convertView: View?, parent: ViewGroup?): View {
        return createViewFromSource(position, convertView, parent, resource)
    }

    private fun createViewFromSource(
        position: Int,
        convertView: View?,
        parent: ViewGroup?,
        resource: Int
    ): View {
        val text: TextView
        val view = convertView ?: LayoutInflater.from(parent?.context).inflate(resource, parent, false)
        try {
            text = view as TextView
        } catch (ex: ClassCastException) {
            throw IllegalStateException("Layout xml is not text field", ex)
        }

        text.text = getItem(position)
        if(position == count - 1) {
            view.setOnClickListener {
                footerClickListener?.onFooterClick()
            }
        } else {
            view.setOnClickListener(null)
            view.isClickable = false
        }

        return view
    }

    override fun getFilter(): Filter {
        return filter
    }

    override fun getDropDownView(position: Int, convertView: View?, parent: ViewGroup?): View {
        return createViewFromSource(position, convertView, parent, resource)
    }

    inner class ArrayFilter: Filter() {
        private var originalValues = ArrayList<T>()

        override fun performFiltering(constraint: CharSequence?): FilterResults {
            val filterResults = FilterResults()
            if(originalValues.isEmpty())
                originalValues.addAll(objects)

            if(constraint == null || constraint.isEmpty()) {
                val outcomes = ArrayList<T>(originalValues)
                filterResults.values = outcomes
                filterResults.count = outcomes.size + 1
            } else {
                val prefixStr = constraint.toString().toLowerCase(Locale.ENGLISH)
                val values = ArrayList<T>(originalValues)

                val newValues = ArrayList<T>()
                for(value in values) {
                    val valueText = value.toString().toLowerCase(Locale.ENGLISH)
                    if(valueText.contains(prefixStr)) {
                        newValues.add(value)
                    } else {
                        val words = valueText.split(" ", "(", ")", ",", "-")
                        for(word in words) {
                            if(word.startsWith(prefixStr)) {
                                newValues.add(value)
                                break
                            }
                        }
                    }
                }

                filterResults.values = newValues
                filterResults.count = newValues.size + 1
            }
            return filterResults
        }

        override fun publishResults(constraint: CharSequence?, results: FilterResults?) {
            @Suppress("UNCHECKED_CAST")
            objects = results?.values as ArrayList<T>
            notifyDataSetChanged()
        }
    }
}

- shafeeq