Question

大家好我开始学习通过udacy构建android应用程序。经过长时间的故障排除后，我没有找到可能导致我所拥有的错误的东西。错误是，当我旋转手机时，视图似乎自己克隆它，而不是删除前一个，如果有人可以帮我生病。 1）app的正常状态：

2）轮换后：

3）并且在另一次轮换之后应用程序崩溃

它直到我在视图的xml文件中添加代码后才会发生：

    <?xml version="1.0" encoding="utf-8"?>

<!-- Layout for weather forecast list item for future day (not today) -->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:gravity="center_vertical"
    android:minHeight="?android:attr/listPreferredItemHeight"
    android:orientation="horizontal"
    android:padding="16dp">

    <ImageView
        android:id="@+id/list_item_icon"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@mipmap/ic_launcher"/>

    <LinearLayout
        android:layout_height="wrap_content"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:orientation="vertical"
        android:paddingLeft="16dp">

        <TextView
            android:id="@+id/list_item_date_textview"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Tomorrow"/>

        <TextView
            android:id="@+id/list_item_forecast_textview"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Clear"/>

    </LinearLayout>

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:layout_weight="1"
        android:gravity="right">

        <TextView
            android:id="@+id/list_item_high_textview"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="81"
            android:paddingLeft="10dp"/>

        <TextView
            android:id="@+id/list_item_low_textview"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="68"
            android:paddingLeft="10dp"/>
    </LinearLayout>

</LinearLayout>

活动代码：

package com.example.andy.sunshine.app;

import android.content.Intent;
import android.content.SharedPreferences;
import android.net.Uri;
import android.os.Bundle;
import android.preference.PreferenceManager;
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.util.Log;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;

public class MainActivity extends AppCompatActivity {
    private String FORECASTFRAGMENT_TAG = "FFTAG";
    String mLocation;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        if (savedInstanceState != null) {
            getSupportFragmentManager().beginTransaction()
                    .add(R.id.fragment, new MainActivityFragment(), FORECASTFRAGMENT_TAG)
                    .commit();
        }
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        mLocation = Utility.getPreferredLocation(this);



        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
    protected void onResume() {
        super.onResume();
        String location = Utility.getPreferredLocation(this);
        if(location != null && location != mLocation){
            MainActivityFragment ff = (MainActivityFragment)getSupportFragmentManager().findFragmentById(R.id.fragment);
            if(ff != null){
                ff.onLocationChanged();
            }
            mLocation = location;
        }
    }

    @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){
            Intent settings = new Intent(this,SettingsActivity.class);
            startActivity(settings);
        }
        if(R.id.action_map == id){
            openPreferedLocationMap();
        }

        return super.onOptionsItemSelected(item);
    }

    private void openPreferedLocationMap(){
        String location = Utility.getPreferredLocation(this);

        Uri geoLocation = Uri.parse("geo:0,0?").buildUpon().appendQueryParameter("q",location).build();

        Intent intent = new Intent(Intent.ACTION_VIEW);
        intent.setData(geoLocation);

        if(intent.resolveActivity(getPackageManager()) != null){
            startActivity(intent);
        }
        else{
            Log.d("SHOWING MAP PROBLEMM","could't call"+ location+ "intent");
        }
    }
}

片段代码：

package com.example.andy.sunshine.app;

import android.content.Intent;
import android.content.SharedPreferences;
import android.database.Cursor;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v4.app.LoaderManager;
import android.support.v4.content.CursorLoader;
import android.support.v4.content.Loader;
import android.text.format.Time;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;

import com.example.andy.sunshine.app.data.WeatherContract;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 * A placeholder fragment containing a simple view.
 */
public class MainActivityFragment extends Fragment implements LoaderManager.LoaderCallbacks<Cursor> {
    private static final int FORECAST_LOADER = 0;
    // For the forecast view we're showing only a small subset of the stored data.
    // Specify the columns we need.
    private static final String[] FORECAST_COLUMNS = {
            // In this case the id needs to be fully qualified with a table name, since
            // the content provider joins the location & weather tables in the background
            // (both have an _id column)
            // On the one hand, that's annoying.  On the other, you can search the weather table
            // using the location set by the user, which is only in the Location table.
            // So the convenience is worth it.
            WeatherContract.WeatherEntry.TABLE_NAME + "." + WeatherContract.WeatherEntry._ID,
            WeatherContract.WeatherEntry.COLUMN_DATE,
            WeatherContract.WeatherEntry.COLUMN_SHORT_DESC,
            WeatherContract.WeatherEntry.COLUMN_MAX_TEMP,
            WeatherContract.WeatherEntry.COLUMN_MIN_TEMP,
            WeatherContract.LocationEntry.COLUMN_LOCATION_SETTING,
            WeatherContract.WeatherEntry.COLUMN_WEATHER_ID,
            WeatherContract.LocationEntry.COLUMN_COORD_LAT,
            WeatherContract.LocationEntry.COLUMN_COORD_LONG
    };

    // These indices are tied to FORECAST_COLUMNS.  If FORECAST_COLUMNS changes, these
    // must change.
    static final int COL_WEATHER_ID = 0;
    static final int COL_WEATHER_DATE = 1;
    static final int COL_WEATHER_DESC = 2;
    static final int COL_WEATHER_MAX_TEMP = 3;
    static final int COL_WEATHER_MIN_TEMP = 4;
    static final int COL_LOCATION_SETTING = 5;
    static final int COL_WEATHER_CONDITION_ID = 6;
    static final int COL_COORD_LAT = 7;
    static final int COL_COORD_LONG = 8;

    private ForecastAdapter mForecastAdapter;

    public MainActivityFragment() {
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // Add this line in order for this fragment to handle menu events.
        setHasOptionsMenu(true);
    }

    @Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
        inflater.inflate(R.menu.forecastfragment, menu);
    }

    @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_refresh) {
            updateWeather();
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // The CursorAdapter will take data from our cursor and populate the ListView.
        mForecastAdapter = new ForecastAdapter(getActivity(), null, 0);

        View rootView = inflater.inflate(R.layout.fragment_main, container, false);

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

        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView adapterView, View view, int position, long l) {
                // CursorAdapter returns a cursor at the correct position for getItem(), or null
                // if it cannot seek to that position.
                Cursor cursor = (Cursor) adapterView.getItemAtPosition(position);
                if (cursor != null) {
                    String locationSetting = Utility.getPreferredLocation(getActivity());
                    Intent intent = new Intent(getActivity(), DetailActivity.class)
                            .setData(WeatherContract.WeatherEntry.buildWeatherLocationWithDate(
                                    locationSetting, cursor.getLong(COL_WEATHER_DATE)
                            ));
                    startActivity(intent);
                }
            }
        });

        return rootView;
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        getLoaderManager().initLoader(FORECAST_LOADER, null, this);
        super.onActivityCreated(savedInstanceState);
    }

    private void updateWeather() {
        FetchWeatherTask weatherTask = new FetchWeatherTask(getActivity());
        String location = Utility.getPreferredLocation(getActivity());
        weatherTask.execute(location);
    }

    public void onLocationChanged(){
        updateWeather();
        getLoaderManager().restartLoader(FORECAST_LOADER,null,this);
    }


    @Override
    public Loader<Cursor> onCreateLoader(int i, Bundle bundle) {
        String locationSetting = Utility.getPreferredLocation(getActivity());

        // Sort order:  Ascending, by date.
        String sortOrder = WeatherContract.WeatherEntry.COLUMN_DATE + " ASC";
        Uri weatherForLocationUri = WeatherContract.WeatherEntry.buildWeatherLocationWithStartDate(
                locationSetting, System.currentTimeMillis());

        return new CursorLoader(getActivity(),
                weatherForLocationUri,
                FORECAST_COLUMNS,
                null,
                null,
                sortOrder);
    }

    @Override
    public void onLoadFinished(Loader<Cursor> cursorLoader, Cursor cursor) {
        mForecastAdapter.swapCursor(cursor);
    }

    @Override
    public void onLoaderReset(Loader<Cursor> cursorLoader) {
        mForecastAdapter.swapCursor(null);
    }
}

扩展CursorAdapter“ForecastAdapter”的类：

package com.example.andy.sunshine.app;

import android.content.Context;
import android.database.Cursor;
import android.support.v4.widget.CursorAdapter;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import com.example.andy.sunshine.app.data.WeatherContract;

/**
 * {@link ForecastAdapter} exposes a list of weather forecasts
 * from a {@link android.database.Cursor} to a {@link android.widget.ListView}.
 */
public class ForecastAdapter extends CursorAdapter {

    private final int VIEW_TYPE_TODAY = 0;
    private final int VIEW_TYPE_FUTURE_DAY = 1;

    public ForecastAdapter(Context context, Cursor c, int flags) {
        super(context, c, flags);
    }

    @Override
    public int getItemViewType(int position) {
        return (position == 0)? VIEW_TYPE_TODAY:VIEW_TYPE_FUTURE_DAY;
    }

    @Override
    public int getViewTypeCount() {
        return 2;
    }

    /**
     * Prepare the weather high/lows for presentation.
     */
    private String formatHighLows(Context context,double high, double low) {
        boolean isMetric = Utility.isMetric(mContext);
        String highLowStr = Utility.formatTemperature(context,high, isMetric) + "/" + Utility.formatTemperature(context,low, isMetric);
        return highLowStr;
    }

    /*
    This is ported from FetchWeatherTask --- but now we go straight from the cursor to the
        string.
    */
    private String convertCursorRowToUXFormat(Context context,Cursor cursor) {
        // get row indices for our cursor
        String highAndLow = formatHighLows(context,
        cursor.getDouble(MainActivityFragment.COL_WEATHER_MAX_TEMP),
        cursor.getDouble(MainActivityFragment.COL_WEATHER_MAX_TEMP));


                return Utility.formatDate(cursor.getLong(MainActivityFragment.COL_WEATHER_DATE)) +
                " - " + cursor.getString(MainActivityFragment.COL_WEATHER_DESC) +
                " - " + highAndLow;
    }

    /*
     Remember that these views are reused as needed.
    */
    @Override
    public View newView(Context context, Cursor cursor, ViewGroup parent) {
        int VIEW_TYPE = getItemViewType(cursor.getPosition());
        int layoutId = -1;
        if(VIEW_TYPE == VIEW_TYPE_TODAY){
            layoutId = R.layout.list_item_forecast_today;
        }else if(VIEW_TYPE == VIEW_TYPE_FUTURE_DAY){
            layoutId = R.layout.list_item_forecast;
        }

        View view = LayoutInflater.from(context).inflate(layoutId, parent, false);
        MyViewHolder viewHolder = new MyViewHolder(view);
        view.setTag(viewHolder);

        return view;
    }

    /*
    This is where we fill-in the views with the contents of the cursor.
    */
    @Override
    public void bindView(View view, Context context, Cursor cursor) {
        // our view is pretty simple here --- just a text view
        // we'll keep the UI functional with a simple (and slow!) binding.
        MyViewHolder viewHolder = (MyViewHolder)view.getTag();

        viewHolder.iconView.setImageResource(R.mipmap.ic_launcher);

        // TODO Read date from cursor
        long dateInMillis = cursor.getLong(MainActivityFragment.COL_WEATHER_DATE);

        viewHolder.dateView.setText(Utility.getFriendlyDayString(context, dateInMillis));

        // TODO Read weather forecast from cursor

        viewHolder.descriptionView.setText(cursor.getString(MainActivityFragment.COL_WEATHER_DESC));

        // Read user preference for metric or imperial temperature units
        boolean isMetric = Utility.isMetric(context);

        // Read high temperature from cursor
        double high = cursor.getDouble(MainActivityFragment.COL_WEATHER_MAX_TEMP);

        viewHolder.highTempView.setText(Utility.formatTemperature(context,high, isMetric));

        // TODO Read low temperature from cursor

        double low = cursor.getDouble(MainActivityFragment.COL_WEATHER_MIN_TEMP);

        viewHolder.lowTempView.setText(Utility.formatTemperature(context,low, isMetric));
    }

    public static class MyViewHolder {
        public final ImageView iconView;
        public final TextView dateView;
        public final TextView descriptionView;
        public final TextView highTempView;
        public final TextView lowTempView;

        public MyViewHolder(View view){
            iconView = (ImageView) view.findViewById(R.id.list_item_icon);
            dateView = (TextView)view.findViewById(R.id.list_item_date_textview);
            descriptionView = (TextView)view.findViewById(R.id.list_item_forecast_textview);
            highTempView = (TextView)view.findViewById(R.id.list_item_high_textview);
            lowTempView = (TextView)view.findViewById(R.id.list_item_low_textview);
        }

    }
}

如果你想查看整个项目并检查可能导致我在这里发布我的github https://github.com/obruchkov/Sunshine的错误，其中包含我所做的所有代码。请帮帮我们

旋转Android手机时应用程序中的错误

0 个答案: