AutoCompleteTextView在 输入数据时可以出现提

        //1.获得AutoCompleteTextView
        AutoCompleteTextView at=(AutoCompleteTextView) findViewById(R.id.att);
        at.setThreshold(1);//设置输入几个字符长度便于出现提示文本
        //2.构建Adapter
        ArrayAdapter<String> adapter=new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1, 
        new String[]{"KK","JJJ","GGG","DDD","YYYY2020"});
        //3.关联Adapter
        at.setAdapter(adapter);

      布局如下   
      <AutoCompleteTextView
        android:id="@+id/att"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="please input" />