エラー 'MainActivityのシンボル' container 'を解決できません

Question

以下は私のMainActivity.Javaファイルのコードです。Can't resolve Symbol 'container'と表示された' Container 'のエラーに直面しています。私がここで間違っていることを誰でも助けることができますか？私のプログラムには他のエラーは全くありません。それはあなたがIDで定義したレイアウトを見つけることができません

package com.example.android.fragmentactivity; 

import android.net.Uri; 
import android.os.Bundle; 
import android.support.design.widget.FloatingActionButton; 
import android.support.design.widget.Snackbar; 
import android.support.v4.app.Fragment; 
import android.support.v7.app.AppCompatActivity; 

public class MainActivity extends AppCompatActivity { 

/** 
    * ATTENTION: This was auto-generated to implement the App Indexing API. 
    * See https://g.co/AppIndexing/AndroidStudio for more information. 
    */ 
private GoogleApiClient client; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    if (savedInstanceState == null) { 
    getSupportFragmentManager().beginTransaction() 
    .add(R.id.container, new PlaceholderFragment()) 
    .commit(); 
    } 
    // ATTENTION: This was auto-generated to implement the App Indexing API. 
    // See https://g.co/AppIndexing/AndroidStudio for more information. 
    client = new GoogleApiClient.Builder(this).addApi(AppIndex.API).build(); 
} 

@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); 

} 

@Override 
public void onStart() { 
    super.onStart(); 

    // ATTENTION: This was auto-generated to implement the App Indexing API. 
    // See https://g.co/AppIndexing/AndroidStudio for more information. 
    client.connect(); 
    Action viewAction = Action.newAction(
    Action.TYPE_VIEW, // TODO: choose an action type. 
    "Main Page", // TODO: Define a title for the content shown. 
    // TODO: If you have web page content that matches this app activity's content, 
    // make sure this auto-generated web page URL is correct. 
    // Otherwise, set the URL to null. 
    Uri.parse("http://host/path"), 
    // TODO: Make sure this auto-generated app deep link URI is correct. 
    Uri.parse("android-app://com.example.android.fragmentactivity/http/host/path") 
); 
    AppIndex.AppIndexApi.start(client, viewAction); 
} 

@Override 
public void onStop() { 
    super.onStop(); 

    // ATTENTION: This was auto-generated to implement the App Indexing API. 
    // See https://g.co/AppIndexing/AndroidStudio for more information. 
    Action viewAction = Action.newAction(
    Action.TYPE_VIEW, // TODO: choose an action type. 
    "Main Page", // TODO: Define a title for the content shown. 
    // TODO: If you have web page content that matches this app activity's content, 
    // make sure this auto-generated web page URL is correct. 
    // Otherwise, set the URL to null. 
    Uri.parse("http://host/path"), 
    // TODO: Make sure this auto-generated app deep link URI is correct. 
    Uri.parse("android-app://com.example.android.fragmentactivity/http/host/path") 
); 
    AppIndex.AppIndexApi.end(client, viewAction); 
    client.disconnect(); 
} 

/** 
    * 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_main, container, false); 


    String[] forecastArray = { 
    "Today , Sunny , 88/63", 
    "Tomorrow , Sunny , 88/63", 
    "Wesneday , Sunny , 88/63", 
    "THursday , Sunny , 88/63", 
    "FRIDAY , Sunny , 88/63", 
    "Saturday , Sunny , 88/63", 
    "Sunday , Sunny , 88/63", 
    }; 

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

    ArrayAdapter <String> mForecastAdapter; 
    mForecastAdapter = new ArrayAdapter <String> (
    getActivity(), 
    R.layout.list_item_forecast, 
    android.R.id.text1, weekForecast); 
    ListView listView = (ListView) rootView.findViewById(R.id.listView_forecast); 
    listView.setAdapter(mForecastAdapter); 
    return rootView; 

    } 

} 
} 

Answer 1

= container

時々、あなたのxmlをチェックしChrisStillwellはコメントで提案のようにIDが同じ

<YourLayout 
     xmlns:android="http://schemas.android.com/apk/res/android" 
     ... 
     android:id="@+id/container" 
     > 

</YourLayout> 

であることを確認最近の変更であれば、再構築によって問題を修正できます。