初学Android，报错求请教

[HZH_aj]

标红的三处编译报错了，求指教，新手！
package com.example.activitytest;

import android.app.Activity;
import android.os.Bundle;
import android.view.Window;
import android.widget.Button;
import android.widget.Toast;

public class FirstActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.first_layout);
Button button1 = (Button) findViewById(R.id.button_1);
button1.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View v){
Toast.makeText(FirstActivity.this, "You clicked Button 1", Toast.LENGTH_LONG).show();
}
});
}
}

[飏飏一蝶]

明显没有导入包，编译器没法识别，导下包就可以，点击黄线弹出提示，导入对应包

[bdmh]

import android.view.View;
import android.view.View.OnClickListener;

[le0102]

alt + /

[tony4geek]

android studio alt+enter

[HZH_aj]

引用 2 楼 bdmh的回复:

import android.view.View;
import android.view.View.OnClickListener;

谢谢可以了这样