Question

我是android studio的新手，我正在尝试运行此代码。

我的代码：

package app.sunshine.android.example.com.sunshine;

import android.app.Activity;
import android.app.ActionBar;
import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.os.Build;
import android.widget.ArrayAdapter;
import android.widget.ListView;

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


public class MyActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my);
        if (savedInstanceState == null) {
            getFragmentManager().beginTransaction()
                    .add(R.id.container, new PlaceholderFragment())
                    .commit();
        }
    }


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

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

        public PlaceholderFragment() {
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_my, container, false);

            // Create some dummy data for the ListView. Here's a sample weekly
            // Represented as "day, whether, high/low"

            String[] forecastArray= {
                    "Today - Sunny - 88/63",
                    "Tomorrow - Foggy - 70/40",
                    "Weds - Cloudy - 72/63",
                    "Thurs - Asteroids - 75/65",
                    "Fri - Heavy Rain - 65/56",
                    "Sat - HELP TRAPPED IN WEATHERSTATION - 60/51",
                    "Sun - Sunny - 80/68"
            };

            List<String> weekForecast = new ArrayList<String>(
                    Arrays.asList(forecastArray));

            // Now that we have some dummy forecast data, create an ArrayAdapter.
            // The ArrayAdapter will take data from a source ( Like our dummy forecast
            // use to populate the ListView it's attached to

            mforecastAdapter =

                    new ArrayAdapter<String>(
                            //The current context( this fragment's parent activity
                            getActivity(),
                            // ID of list item layout
                            R.layout.list_item_forecast,
                            // ID of the textview to populate
                            R.id.list_item_forecast_textview,
                            // Forecast data
                            weekForecast);

            // Get a reference to the LIstView and attach this adpater to it
            ListView listView = (ListView) rootView.findViewById(
                    R.id.listview_forecast);
            listView.setAdapter(mForecastAdapter);



            return rootView;
        }
    }
}

但是我收到以下错误：cannot find symbol variable

我尝试清理项目gradle并重新启动android应用程序。但我仍然遇到这个问题

任何帮助将不胜感激:)

我正在关注本教程https://www.udacity.com/course/viewer#!/c-ud853/l-1395568821/e-1395668601/m-1395668603

Answer 1

您需要声明mForecastAdapter。

public static class PlaceholderFragment extends Fragment {
        ArrayAdapter<String> mForecastAdapter;
        public PlaceholderFragment() {
        }

由于您还没有这样做，它无法识别变量mForecastAdapter。希望这会有所帮助。

找不到符号变量Android Studio 0.8.1

1 个答案: