Android：AutoCompleteTextView在没有输入文本时显示建议

Question

我正在使用AutoCompleteTextView，当用户点击它时，我想显示建议，即使它没有文字 - 但setThreshold(0)的工作原理与setThreshold(1)完全相同 - 所以用户必须输入至少1个字符才能显示建议。

Answer 1

这是documented behavior：

  

当threshold小于或等于0时，阈值为1   应用

您可以通过showDropDown()手动显示下拉列表，因此您可以安排在需要时显示该下拉列表。或者，子类AutoCompleteTextView并覆盖enoughToFilter()，一直返回true。

Answer 2

这是我的班级 InstantAutoComplete 。它位于AutoCompleteTextView和Spinner之间。

import android.content.Context;  
import android.graphics.Rect;
import android.util.AttributeSet;
import android.widget.AutoCompleteTextView;

public class InstantAutoComplete extends AutoCompleteTextView {

    public InstantAutoComplete(Context context) {
        super(context);
    }

    public InstantAutoComplete(Context arg0, AttributeSet arg1) {
        super(arg0, arg1);
    }

    public InstantAutoComplete(Context arg0, AttributeSet arg1, int arg2) {
        super(arg0, arg1, arg2);
    }

    @Override
    public boolean enoughToFilter() {
        return true;
    }

    @Override
    protected void onFocusChanged(boolean focused, int direction,
            Rect previouslyFocusedRect) {
        super.onFocusChanged(focused, direction, previouslyFocusedRect);
        if (focused && getAdapter() != null) {
            performFiltering(getText(), 0);
        }
    }

}

在xml中使用它，如下所示：

<your.namespace.InstantAutoComplete ... />

Answer 3

最简单的方法：

只需使用setOnTouchListener和showDropDown（）

AutoCompleteTextView text;
.....
.....
text.setOnTouchListener(new View.OnTouchListener(){
   @Override
   public boolean onTouch(View v, MotionEvent event){
      text.showDropDown();
      return false;
   }
});

Answer 4

当只有一个InstantAutoComplete对象时，Destil的代码效果很好。 虽然不适用于两个人 - 不明白为什么。但是当我把showDropDown()（就像CommonsWare建议的那样）放到这样的onFocusChanged()中时：

@Override
protected void onFocusChanged(boolean focused, int direction,
        Rect previouslyFocusedRect) {
    super.onFocusChanged(focused, direction, previouslyFocusedRect);
    if (focused) {
        performFiltering(getText(), 0);
        showDropDown();
    }
}

它解决了这个问题。

这两个答案恰好合并，但我希望它可以节省一些时间。

Answer 5

适配器最初不执行过滤 未执行过滤时，下拉列表为空 所以你可能必须先进行过滤。

为此，您可以在添加完条目后调用filter()：

adapter.add("a1");
adapter.add("a2");
adapter.add("a3");
adapter.getFilter().filter(null);

Answer 6

上面的Destil的回答几乎可行，但有一个微妙的错误。当用户首先将焦点放在字段上时它会起作用，但是如果它们离开然后返回到字段，它将不会显示下拉列表，因为mPopupCanBeUpdated的值在隐藏时仍然为false。修复方法是将onFocusChanged方法更改为：

@Override
protected void onFocusChanged(boolean focused, int direction,
        Rect previouslyFocusedRect) {
    super.onFocusChanged(focused, direction, previouslyFocusedRect);
    if (focused) {
        if (getText().toString().length() == 0) {
            // We want to trigger the drop down, replace the text.
            setText("");
        }
    }
}

Answer 7

您可以使用onFocusChangeListener;

TCKimlikNo.setOnFocusChangeListener(new OnFocusChangeListener() {

        @Override
        public void onFocusChange(View v, boolean hasFocus) {
            if (hasFocus) {
                TCKimlikNo.showDropDown();

            }

        }
    });

Answer 8

制作CustomAutoCompleteTextView。 1.覆盖setThreshold，enoughToFilter，onFocusChanged方法

public class CustomAutoCompleteTextView  extends AutoCompleteTextView { 

    private int myThreshold; 

    public CustomAutoCompleteTextView  (Context context) { 
        super(context); 
    } 

    public CustomAutoCompleteTextView  (Context context, AttributeSet attrs, int defStyle) { 
        super(context, attrs, defStyle); 
    } 

    public CustomAutoCompleteTextView  (Context context, AttributeSet attrs) { 
        super(context, attrs); 
    } 
     //set threshold 0.
    public void setThreshold(int threshold) { 
        if (threshold < 0) { 
            threshold = 0; 
        } 
        myThreshold = threshold; 
    } 
    //if threshold   is 0 than return true
    public boolean enoughToFilter() { 
         return true;
        } 
    //invoke on focus 
    protected void onFocusChanged(boolean focused, int direction,
            Rect previouslyFocusedRect) {
                    //skip space and backspace 
        super.performFiltering("", 67);
        // TODO Auto-generated method stub
        super.onFocusChanged(focused, direction, previouslyFocusedRect);

    }

    protected void performFiltering(CharSequence text, int keyCode) {
        // TODO Auto-generated method stub
        super.performFiltering(text, keyCode);
    }

    public int getThreshold() { 
        return myThreshold; 
    } 
}

Answer 9

试试吧

    searchAutoComplete.setThreshold(0);
    searchAutoComplete.addTextChangedListener(new TextWatcher() {
                @Override
                public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
                }

                @Override
                public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {//cut last probel
                    if (charSequence.length() > 1) {
                        if (charSequence.charAt(charSequence.length() - 1) == ' ') {
                            searchAutoComplete.setText(charSequence.subSequence(0, charSequence.length() - 1));
                            searchAutoComplete.setSelection(charSequence.length() - 1);
                        }
                    }
                   }


                @Override
                public void afterTextChanged(Editable editable) {
                }
            });


    //when clicked in autocomplete text view
        @Override
        public void onClick(View view) {
            switch (view.getId()) {
              case R.id.header_search_etv:
                    if (searchAutoComplete.getText().toString().length() == 0) {
                        searchAutoComplete.setText(" ");
                    }
             break;
            }
        }):

Answer 10

只需在触摸时点击此方法或点击autoCompleteTextView的事件或您想要的位置。

autoCompleteTextView.showDropDown()

Answer 11

这对我有用，伪代码：

    public class CustomAutoCompleteTextView extends AutoCompleteTextView {
    public CustomAutoCompleteTextView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    public boolean enoughToFilter() {
        return true;
    }

    @Override
    protected void onFocusChanged(boolean focused, int direction, Rect previouslyFocusedRect) {
        super.onFocusChanged(focused, direction, previouslyFocusedRect);
        if (focused) {
            performFiltering(getText(), 0);
        }
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        this.showDropDown();
        return super.onTouchEvent(event);
    }
}

Answer 12

只需将其粘贴到Java中的onCreate方法

即可

final ArrayAdapter<String> arrayAdapter = new ArrayAdapter<>(
            this, android.R.layout.simple_spinner_dropdown_item,
            getResources().getStringArray(R.array.Loc_names));

    textView1 =(AutoCompleteTextView) findViewById(R.id.acT1);
    textView1.setAdapter(arrayAdapter);

    textView1.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(final View arg0) {
            textView1.setMaxLines(5);
            textView1.showDropDown();

        }
    });

这是你的Xml文件......

<AutoCompleteTextView
            android:layout_width="200dp"
            android:layout_height="30dp"
            android:hint="@string/select_location"
            android:id="@+id/acT1"
            android:textAlignment="center"/>

在Values ...

下的string.xml中创建一个数组

<string-array name="Loc_names">

        <item>Pakistan</item>
        <item>Germany</item>
        <item>Russia/NCR</item>
        <item>China</item>
        <item>India</item>
        <item>Sweden</item>
        <item>Australia</item>
    </string-array>

你很高兴。

Answer 13

七年后，伙计们，问题保持不变。这是一个带有函数的类，它强制愚蠢的弹出窗口在任何条件下显示自己。您需要做的就是将适配器设置为AutoCompleteTextView，向其中添加一些数据，并随时调用showDropdownNow()函数。

@DavidVávra的积分。这是基于他的代码。

import android.content.Context
import android.util.AttributeSet
import android.widget.AutoCompleteTextView

class InstantAutoCompleteTextView : AutoCompleteTextView {

    constructor(context: Context) : super(context)

    constructor(context: Context?, attrs: AttributeSet?) : super(context, attrs)

    constructor(context: Context?, attrs: AttributeSet?, defStyleAttr: Int) : super(context, attrs, defStyleAttr)

    override fun enoughToFilter(): Boolean {
        return true
    }

    fun showDropdownNow() {
        if (adapter != null) {
            // Remember a current text
            val savedText = text

            // Set empty text and perform filtering. As the result we restore all items inside of
            // a filter's internal item collection.
            setText(null, true)

            // Set back the saved text and DO NOT perform filtering. As the result of these steps
            // we have a text shown in UI, and what is more important we have items not filtered
            setText(savedText, false)

            // Move cursor to the end of a text
            setSelection(text.length)

            // Now we can show a dropdown with full list of options not filtered by displayed text
            performFiltering(null, 0)
        }
    }
}

Answer 14

在FocusChangeListener上，检查

bottom: 0

在过滤器中，只需修整此值：

if (hasFocus) {
            tvAutoComplete.setText(" ")

，当您专注于此视图时，它将显示所有建议。