阅读下列代码,回答问题:语句2的作用是( )。 final AutoCompleteTextView searchAV = (AutoCompleteTextView) findViewById(R.id.searchAV); //语句1 ArrayAdapter adapter = new ArrayAdapter (this, android.R.layout.simple_dropdown_item_1line, DATA); //语句2 searchAV.setAdapter(adapter); //语句3 Button searchBT = (Button) findViewById(R.id.searchBT); searchBT.setOnClickListener(new OnClickListener() { @Override public void onClick(View arg0) { Toast.makeText(MainActivity.this, searchAV.getText().toString(), Toast.LENGTH_SHORT) .show(); //语句4 } });