为什么ArrayAdapter不适用于Android Studio 2.0？

Question

我正在开发Android Studio 2.0和我的Samsung Galaxy J5。 当我必须在MainActivityFragment上初始化一个ArrayAdapter时：Android Studio（或Java）说“无法解析符号'ArrayAdapter''，因此我将Udacity的课程”开发Android应用程序“作为开发者（伟大课程！ 我后我的代码：

MainActivityFragment.java

package com.example.android.sunshineapp; 

import android.os.Bundle; 
import android.support.v4.app.Fragment; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.Adapter; 

import java.util.ArrayList; 
import java.util.Arrays; 
import java.util.List; 

/** 
* A placeholder fragment containing a simple view. 
*/ 
public class MainActivityFragment extends Fragment { 

    ArrayAdapter<String> mForecastAdapter; 
    public MainActivityFragment() { 
    } 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
          Bundle savedInstanceState) { 
     String[] array; 
     array = new String[]{ 
       "Mon 6/23 - Sunny - 31/17", 
       "Tue 6/24 - Foggy - 21/8", 
       "Wed 6/25 - Cloudy - 22/17", 
       "Thurs 6/26 - Rainy - 18/11", 
       "Fri 6/27 - Foggy - 21/10", 
       "Sat 6/28 - TRAPPED IN WEATHERSTATION - 23/18", 
       "Sun 6/29 - Sunny - 20/7" 
     }; 
     List<String> weekForecast = new ArrayList<String>(Arrays.asList(array)); 

     mForecastAdapter = new ArrayAdapter<String>(getActivity(), R.layout.list_item_forecast, R.id.list_item_forecast_textview, weekForecast); 

     return inflater.inflate(R.layout.fragment_main, container, false); 



    } 
} 

MainActivity.java

package com.example.android.sunshineapp; 

import android.os.Bundle; 
import android.support.design.widget.FloatingActionButton; 
import android.support.design.widget.Snackbar; 
import android.support.v7.app.AppCompatActivity; 
import android.support.v7.widget.Toolbar; 
import android.view.View; 
import android.view.Menu; 
import android.view.MenuItem; 

public class MainActivity extends AppCompatActivity { 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); 
     setSupportActionBar(toolbar); 

     FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab); 
     fab.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View view) { 
       Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG) 
         .setAction("Action", null).show(); 
      } 
     }); 

    } 

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

    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     // Handle action bar item clicks here. The action bar will 
     // automatically handle clicks on the Home/Up button, so long 
     // as you specify a parent activity in AndroidManifest.xml. 
     int id = item.getItemId(); 

     //noinspection SimplifiableIfStatement 
     if (id == R.id.action_settings) { 
      return true; 
     } 

     return super.onOptionsItemSelected(item); 
    } 
} 

Answer 1

你缺少：

import android.widget.ArrayAdapter;