Ловлю ошибку в Logcat AndroidStudio

Question

при компиляции кода выходит ошибка, подскажите в чем проблема

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">


  <TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="New Text"
    android:id="@+id/textView2"
    android:layout_alignParentTop="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true" />

  <ListView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/listView"
    android:layout_below="@+id/textView2"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true" />
</RelativeLayout>

MainActivity.java

public class MainActivity extends ActionBarActivity {

ListView mList;
TextView header;
DatabaseHelper sqlHelper;
Cursor userCursor;
SimpleCursorAdapter userAdapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    header = (TextView) findViewById(R.id.header);
    mList = (ListView) findViewById(R.id.list);

    mList.setOnItemClickListener(new  AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int     position, long id) {

            Intent intent = new Intent(getApplicationContext(), UserActivity.class);
            intent.putExtra("id", id);
            startActivity(intent);
        }
    });
    sqlHelper = new DatabaseHelper(getApplicationContext());
    // создаем базу данных
    sqlHelper.create_db();
}
@Override
public void onResume(){
    super.onResume();
    try {
        sqlHelper.open();
        userCursor = sqlHelper.database.rawQuery("select * from " + DatabaseHelper.TABLE, null);
        String[] headers = new String[]{DatabaseHelper.COLUMN_NAME, DatabaseHelper.COLUMN_DESCRIPTION,
        DatabaseHelper.COLUMN_ADDRESS,DatabaseHelper.COLUMN_PHONE};
        userAdapter = new SimpleCursorAdapter(this, android.R.layout.two_line_list_item,
                userCursor, headers, new int[]{android.R.id.text1, android.R.id.text2}, 0);
        header.setText("Найдено элементов: " + String.valueOf(userCursor.getCount()));
        mList.setAdapter(userAdapter);
    }
    catch (SQLException ex){}
}

@Override
public void onDestroy(){
    super.onDestroy();
    // Закрываем подключения
    sqlHelper.database.close();
    userCursor.close();
}

  /* @Override
public boolean onCreateOptionsMenu(Menu menu) {

    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {

  *//*  int id = item.getItemId();
    if (id == R.id.action_settings) {

        Intent intent = new Intent(getApplicationContext(), UserActivity.class);
        startActivity(intent);
        return true;
    }
    return super.onOptionsItemSelected(item);*//*
 }*/
}

DatabaseHelper.java

public class DatabaseHelper extends SQLiteOpenHelper {

private static String DB_PATH = "/data/data/com.vakhrushevv.primer/databases/";
private static String DB_NAME = "th";
private static final int SCHEMA = 1; // версия базы данных
static final String TABLE = "public authorities";

public static final String COLUMN_ID = "_id";
public static final String COLUMN_NAME = "Наименование";
public static final String COLUMN_DESCRIPTION = "Описание";
public static final String COLUMN_ADDRESS = "Адрес";
public static final String COLUMN_PHONE = "Телефон";
public SQLiteDatabase database;
private Context myContext;

public DatabaseHelper(Context context) {
    super(context, DB_NAME, null, SCHEMA);
    this.myContext=context;
}

@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion,  int newVersion) {

}

public void create_db(){
    InputStream myInput = null;
    OutputStream myOutput = null;
    try {
        File file = new File(DB_PATH + DB_NAME);
        if (!file.exists()) {
            this.getReadableDatabase();
            //получаем локальную бд как поток
            myInput = myContext.getAssets().open(DB_NAME);
            // Путь к новой бд
            String outFileName = DB_PATH + DB_NAME;

            // Открываем пустую бд
            myOutput = new FileOutputStream(outFileName);

            // побайтово копируем данные
            byte[] buffer = new byte[1024];
            int length;
            while ((length = myInput.read(buffer)) > 0) {
                myOutput.write(buffer, 0, length);
            }

            myOutput.flush();
            myOutput.close();
            myInput.close();
        }
    }
    catch(IOException ex){

    }
}
public void open() throws SQLException {
    String path = DB_PATH + DB_NAME;
    database = SQLiteDatabase.openDatabase(path, null,
            SQLiteDatabase.OPEN_READWRITE);

}

@Override
public synchronized void close() {
    if (database != null) {
        database.close();
    }
    super.close();
 }
}

LOGCAT

04-07 13:29:09.410 3609-3609/? I/art: Not late-enabling -Xcheck:jni (already on)
    04-07 13:29:09.678 3609-3609/com.vakhrushevv.primer W/System: ClassLoader referenced unknown path: /data/app/com.vakhrushevv.primer-2/lib/x86
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer D/AndroidRuntime: Shutting down VM
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime: FATAL EXCEPTION: main
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime: Process: com.vakhrushevv.primer, PID: 3609
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.vakhrushevv.primer/com.vakhrushevv.primer.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setOnItemClickListener(android.widget.AdapterView$OnItemClickListener)' on a null object reference
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime:     at android.app.ActivityThread.-wrap11(ActivityThread.java)
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:102)
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:148)
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:5417)
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Native Method)
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime:  Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setOnItemClickListener(android.widget.AdapterView$OnItemClickListener)' on a null object reference
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime:     at com.vakhrushevv.primer.MainActivity.onCreate(MainActivity.java:43)
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime:     at android.app.Activity.performCreate(Activity.java:6237)
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime:     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime:     at android.app.ActivityThread.-wrap11(ActivityThread.java) 
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:102) 
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:148) 
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:5417) 
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Native Method) 
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
    04-07 13:29:09.956 3609-3609/com.vakhrushevv.primer E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
    04-07 13:29:13.857 3609-3609/com.vakhrushevv.primer I/Process: Sending signal. PID: 3609 SIG: 9

В ошибке вам написано, что ваша переменная mList - null. Проверьте разметку, ID. — ЮрийСПб, Apr 07 '16 at 13:53
И у вас слишком много лишнего кода в вопросе - уважайте тех, кто захочет помочь - им сложно будет принять решение попытаться разобраться в столь обширном тексте при том, что вы даже не попытались его сами сократить — ЮрийСПб, Apr 07 '16 at 13:55
Если вам дан исчерпывающий ответ, отметьте его как верный (галка напротив выбранного ответа). — Nicolas Chabanovsky, Apr 07 '16 at 18:39
Возможный дубликат вопроса: Что такое Null Pointer Exception и как его исправить? — Pavel Mayorov, May 19 '16 at 05:33

score 4 · Answer 1 · answered Apr 07 '16 at 14:05

Классическая ошибка, у вас не правильные id ссылки на Вью. Замените в onCreate

header = (TextView) findViewById(R.id.header);
mList = (ListView) findViewById(R.id.list);

на

header = (TextView) findViewById(R.id.textView2);
mList = (ListView) findViewById(R.id.listView);

Ловлю ошибку в Logcat AndroidStudio

1 Answers1