I'll get a "null pointer exception"-error since I the viewholder don't find any Checkbox.Anyone know how I fix this?This is the row that get's an error: viewHolder.getCheckBox().setChecked( Exercise.isChecked() );(Marked with arrows further down)XML EditWorkout.xml:\[code\]<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android
rientation="vertical"> <Spinner android:id="@+id/spinner1" android:layout_width="match_parent" android:layout_height="wrap_content" /> <ListView android:id="@+id/mainListView" android:layout_width="fill_parent" android:layout_height="0dp" android:layout_weight="1" /> <LinearLayout android:layout_width="fill_parent" android:layout_height="60dp" android:layout_weight="0" android:gravity="bottom"><Button android:id="@+id/button_EditWorkout_Save" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Save"/><Button android:id="@+id/button_Workout_Cancel" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Cancel"/> </LinearLayout></LinearLayout>\[/code\]XML Simplerow.xml\[code\]<?xml version="1.0" encoding="utf-8" ?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" androidrientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent"> <TextView android:id="@+id/rowTextView" android:layout_width="wrap_content" android:layout_height="wrap_content" android
adding="10dp" android:textSize="16sp" /> <CheckBox android:id="@+id/CheckBox01" android:layout_width="wrap_content" android:layout_height="wrap_content" androidadding="10dp" android:layout_alignParentRight="true" android:layout_marginRight="6sp" android:focusable="false" /> </RelativeLayout>\[/code\]Java EditWorkout:\[code\] public class EditWorkout extends SherlockActivity implements OnItemSelectedListener { private ListView mainListView; private ArrayAdapter<Exercise> listAdapter; private String workoutName; ArrayList<Exercise> exerciseList = new ArrayList<Exercise>(); @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Intent intent = getIntent(); workoutName = intent.getStringExtra(ListWorkoutActivity.WORKOUT_NAME); setContentView(R.layout.editworkout); // Find the ListView resource. mainListView = (ListView) findViewById( R.id.mainListView ); // When item is tapped, toggle checked properties of CheckBox and Exercise. mainListView.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick( AdapterView<?> parent, View item, int position, long id) { Exercise Exercise = listAdapter.getItem( position ); Exercise.toogleChecked(); ExerciseViewHolder viewHolder = (ExerciseViewHolder) item.getTag(); -----> viewHolder.getCheckBox().setChecked( Exercise.isChecked() <------ ); }//End of onItemClick });//End of Listener // Since we don't have a database we manually put in exercises //Could use a Arraylist directly but we use a String since we will load //String-Arrays from the database we use a String-array here if(exerciseList.isEmpty()) { exerciseList.add(new Exercise("pushup")); exerciseList.add(new Exercise("sit-up")); exerciseList.add(new Exercise("sit-up")); exerciseList.add(new Exercise("sit-up")); exerciseList.add(new Exercise("sit-up")); } // Set our custom Arrayadapter as the ListView's adapter. listAdapter = new ExerciseArrayAdapter(this, exerciseList); mainListView.setAdapter( listAdapter ); }\[/code\]Java Exercise:\[code\]public class Exercise { private String name = "" ; private boolean checked = false ; /** * */ public Exercise( String name ) { this.name = name ; } public Exercise( String name, boolean checked ) { this.name = name ; this.checked = checked ; } public String getName() { return name; } public boolean isChecked() { return checked; } public void setChecked(boolean checked) { this.checked = checked; } public String toString() { return name ; } public void toogleChecked() { checked = !checked ; } } \[/code\]Java ExerciseViewHolder:\[quote\] public class ExerciseViewHolder { private CheckBox checkBox; private TextView textView;\[code\] /** * Creates a new holder with the given name and a checkbox * The name is the name of the exercise */ public ExerciseViewHolder( TextView textView, CheckBox checkBox ) { this.checkBox = checkBox; this.textView = textView; } /** * Gets the checkbox of the holder * @return the holders checkbox. */ public CheckBox getCheckBox() { return checkBox; } /** * Gets the name of the holder * @return the holders name */ public TextView getTextView() { return textView; } }\[/code\]\[/quote\]\[code\]public class ExerciseArrayAdapter extends ArrayAdapter<Exercise> { private LayoutInflater inflater; public ExerciseArrayAdapter( Context context, List<Exercise> exerciseList ) { super( context, R.layout.simplerow, R.id.rowTextView, exerciseList ); // Cache the LayoutInflate to avoid asking for a new one each time. inflater = LayoutInflater.from(context); } /**Since we display other things than a TextView we need to Override a getView-method. * This method is the one that got the focus on the screen and is returning the View * when the user clicks on a exercise. * @param position The place where the user clicks refereed as an Int. * @param convertView The view, each view will be represented as an simplerow * with an textfield and a checkbox. * @return View*/ public View getView(int position, View convertView) { // Exercise to display Exercise exercise = (Exercise) this.getItem( position ); Log.v("Convertview", String.valueOf(position)); //What each view contains. CheckBox checkBox; TextView textView; //If the view doesn't exist, we create a new row view. Initially //the screen is filled up, when the screen is full the convertView // is not null and will there after go to the else-statement if ( convertView == null) { convertView = inflater.inflate(R.layout.simplerow, null); // Find the child views. textView = (TextView) convertView.findViewById( R.id.rowTextView ); checkBox = (CheckBox) convertView.findViewById( R.id.CheckBox01 ); // Optimization: Tag the row with it's child views, so we don't have to // call findViewById() later when we reuse the row in our else case. convertView.setTag( new ExerciseViewHolder(textView,checkBox) ); // If CheckBox is toggled, update the Exercise it is tagged with. checkBox.setOnClickListener( new View.OnClickListener() { /** When the user click on a exercise, the checkbox * for the exercise is getting unchecked or checked * @param v The view the user clicks on, this view will * refeer to a exercise since the view contains * a exercise. * */ public void onClick(View v) { CheckBox cb = (CheckBox) v; Exercise exercise = (Exercise) cb.getTag(); exercise.setChecked( cb.isChecked() ); } }); } //Is used when the user are scrolling down or up to list existing views but now the //the elements in the highest view with another element if the user scroll up or //the lowest view if the user scroll down. else { // Because we use a ViewHolder, we avoid having to call findViewById(). ExerciseViewHolder viewHolder = (ExerciseViewHolder) convertView.getTag(); checkBox = viewHolder.getCheckBox(); textView = viewHolder.getTextView(); } // Tag the CheckBox with the Exercise it is displaying, so that we can // access the Exercise in onClick() when the CheckBox is clicked. checkBox.setTag( exercise ); // Display Exercise checkBox.setChecked( exercise.isChecked() ); textView.setText( exercise.getName() ); return convertView; } }\[/code\]
rientation="vertical"> <Spinner android:id="@+id/spinner1" android:layout_width="match_parent" android:layout_height="wrap_content" /> <ListView android:id="@+id/mainListView" android:layout_width="fill_parent" android:layout_height="0dp" android:layout_weight="1" /> <LinearLayout android:layout_width="fill_parent" android:layout_height="60dp" android:layout_weight="0" android:gravity="bottom"><Button android:id="@+id/button_EditWorkout_Save" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Save"/><Button android:id="@+id/button_Workout_Cancel" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Cancel"/> </LinearLayout></LinearLayout>\[/code\]XML Simplerow.xml\[code\]<?xml version="1.0" encoding="utf-8" ?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" androidrientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent"> <TextView android:id="@+id/rowTextView" android:layout_width="wrap_content" android:layout_height="wrap_content" androidadding="10dp" android:textSize="16sp" /> <CheckBox android:id="@+id/CheckBox01" android:layout_width="wrap_content" android:layout_height="wrap_content" androidadding="10dp" android:layout_alignParentRight="true" android:layout_marginRight="6sp" android:focusable="false" /> </RelativeLayout>\[/code\]Java EditWorkout:\[code\] public class EditWorkout extends SherlockActivity implements OnItemSelectedListener { private ListView mainListView; private ArrayAdapter<Exercise> listAdapter; private String workoutName; ArrayList<Exercise> exerciseList = new ArrayList<Exercise>(); @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Intent intent = getIntent(); workoutName = intent.getStringExtra(ListWorkoutActivity.WORKOUT_NAME); setContentView(R.layout.editworkout); // Find the ListView resource. mainListView = (ListView) findViewById( R.id.mainListView ); // When item is tapped, toggle checked properties of CheckBox and Exercise. mainListView.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick( AdapterView<?> parent, View item, int position, long id) { Exercise Exercise = listAdapter.getItem( position ); Exercise.toogleChecked(); ExerciseViewHolder viewHolder = (ExerciseViewHolder) item.getTag(); -----> viewHolder.getCheckBox().setChecked( Exercise.isChecked() <------ ); }//End of onItemClick });//End of Listener // Since we don't have a database we manually put in exercises //Could use a Arraylist directly but we use a String since we will load //String-Arrays from the database we use a String-array here if(exerciseList.isEmpty()) { exerciseList.add(new Exercise("pushup")); exerciseList.add(new Exercise("sit-up")); exerciseList.add(new Exercise("sit-up")); exerciseList.add(new Exercise("sit-up")); exerciseList.add(new Exercise("sit-up")); } // Set our custom Arrayadapter as the ListView's adapter. listAdapter = new ExerciseArrayAdapter(this, exerciseList); mainListView.setAdapter( listAdapter ); }\[/code\]Java Exercise:\[code\]public class Exercise { private String name = "" ; private boolean checked = false ; /** * */ public Exercise( String name ) { this.name = name ; } public Exercise( String name, boolean checked ) { this.name = name ; this.checked = checked ; } public String getName() { return name; } public boolean isChecked() { return checked; } public void setChecked(boolean checked) { this.checked = checked; } public String toString() { return name ; } public void toogleChecked() { checked = !checked ; } } \[/code\]Java ExerciseViewHolder:\[quote\] public class ExerciseViewHolder { private CheckBox checkBox; private TextView textView;\[code\] /** * Creates a new holder with the given name and a checkbox * The name is the name of the exercise */ public ExerciseViewHolder( TextView textView, CheckBox checkBox ) { this.checkBox = checkBox; this.textView = textView; } /** * Gets the checkbox of the holder * @return the holders checkbox. */ public CheckBox getCheckBox() { return checkBox; } /** * Gets the name of the holder * @return the holders name */ public TextView getTextView() { return textView; } }\[/code\]\[/quote\]\[code\]public class ExerciseArrayAdapter extends ArrayAdapter<Exercise> { private LayoutInflater inflater; public ExerciseArrayAdapter( Context context, List<Exercise> exerciseList ) { super( context, R.layout.simplerow, R.id.rowTextView, exerciseList ); // Cache the LayoutInflate to avoid asking for a new one each time. inflater = LayoutInflater.from(context); } /**Since we display other things than a TextView we need to Override a getView-method. * This method is the one that got the focus on the screen and is returning the View * when the user clicks on a exercise. * @param position The place where the user clicks refereed as an Int. * @param convertView The view, each view will be represented as an simplerow * with an textfield and a checkbox. * @return View*/ public View getView(int position, View convertView) { // Exercise to display Exercise exercise = (Exercise) this.getItem( position ); Log.v("Convertview", String.valueOf(position)); //What each view contains. CheckBox checkBox; TextView textView; //If the view doesn't exist, we create a new row view. Initially //the screen is filled up, when the screen is full the convertView // is not null and will there after go to the else-statement if ( convertView == null) { convertView = inflater.inflate(R.layout.simplerow, null); // Find the child views. textView = (TextView) convertView.findViewById( R.id.rowTextView ); checkBox = (CheckBox) convertView.findViewById( R.id.CheckBox01 ); // Optimization: Tag the row with it's child views, so we don't have to // call findViewById() later when we reuse the row in our else case. convertView.setTag( new ExerciseViewHolder(textView,checkBox) ); // If CheckBox is toggled, update the Exercise it is tagged with. checkBox.setOnClickListener( new View.OnClickListener() { /** When the user click on a exercise, the checkbox * for the exercise is getting unchecked or checked * @param v The view the user clicks on, this view will * refeer to a exercise since the view contains * a exercise. * */ public void onClick(View v) { CheckBox cb = (CheckBox) v; Exercise exercise = (Exercise) cb.getTag(); exercise.setChecked( cb.isChecked() ); } }); } //Is used when the user are scrolling down or up to list existing views but now the //the elements in the highest view with another element if the user scroll up or //the lowest view if the user scroll down. else { // Because we use a ViewHolder, we avoid having to call findViewById(). ExerciseViewHolder viewHolder = (ExerciseViewHolder) convertView.getTag(); checkBox = viewHolder.getCheckBox(); textView = viewHolder.getTextView(); } // Tag the CheckBox with the Exercise it is displaying, so that we can // access the Exercise in onClick() when the CheckBox is clicked. checkBox.setTag( exercise ); // Display Exercise checkBox.setChecked( exercise.isChecked() ); textView.setText( exercise.getName() ); return convertView; } }\[/code\]