@Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_courses); db = new DBHelper(this); semester = (Semester) getIntent().getSerializableExtra("semester"); courses = semester.getCourses(); coursesListView = (ListView) findViewById(R.id.coursesListView); adapter = new CourseAdapter(this, R.layout.semester_row, courses); coursesListView.setAdapter(adapter); coursesListView.setOnItemClickListener( new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { Intent intent = new Intent(Courses.this, EditCourse.class); intent.putExtra("course", courses.get(position)); startActivity(intent); } }); semesterAverageTextView = (TextView) findViewById(R.id.semesterAverageTextView); totalAverageTextView = (TextView) findViewById(R.id.totalAverageTextView); calculateAverages(); }