Javadoc for Android project in Eclipse fails with NullPointerException

Question

I am trying to generate javadoc comments in Eclipse for my Android Project, but I keep getting a NullPointerException. The problem occurs only when I try to generate javadocs for classes that import the Android Compatibility Library (android.support), which I have attached as an external jar. I also reference Android 2.2 and several Library Projects, but those do not cause this error on their own.

Loading source file /home/travisc/Desktop/Android/App/workspace/Restaurant/src/com/yellowbrickcode/restaurant/StartupActivity.java...
Constructing Javadoc information...
StartupActivity.java:3: package android.content does not exist
import android.content.ContentValues;
                      ^
StartupActivity.java:4: package android.content does not exist
import android.content.Intent;
                      ^
StartupActivity.java:5: package android.content does not exist
import android.content.SharedPreferences;
                      ^
StartupActivity.java:6: package android.content.SharedPreferences does not exist
import android.content.SharedPreferences.Editor;
                                        ^
StartupActivity.java:7: package android.os does not exist
import android.os.Bundle;
                 ^
StartupActivity.java:8: package android.preference does not exist
import android.preference.PreferenceManager;
                         ^
StartupActivity.java:10: package android.view does not exist
import android.view.Menu;
                   ^
StartupActivity.java:11: package android.view does not exist
import android.view.MenuItem;
                   ^
StartupActivity.java:12: package android.view does not exist
import android.view.View;
                   ^
StartupActivity.java:14: package android.view does not exist
import android.view.ViewGroup;
                   ^
StartupActivity.java:15: package android.widget does not exist
import android.widget.ImageButton;
                     ^
StartupActivity.java:27: cannot access android.app.Activity
class file for android.app.Activity not found
public class StartupActivity extends FragmentActivity {
       ^
StartupActivity.java:29: cannot find symbol
symbol  : class OnClickListener
location: class com.yellowbrickcode.restaurant.StartupActivity
    private OnClickListener mMenuListener = new OnClickListener() {
            ^
StartupActivity.java:38: cannot find symbol
symbol  : class OnClickListener
location: class com.yellowbrickcode.restaurant.StartupActivity
    private OnClickListener mAccountListener = new OnClickListener() {
            ^
StartupActivity.java:49: cannot find symbol
symbol  : class OnClickListener
location: class com.yellowbrickcode.restaurant.StartupActivity
    private OnClickListener mCheckinListener = new OnClickListener() {
            ^
StartupActivity.java:68: cannot find symbol
symbol  : class Menu
location: class com.yellowbrickcode.restaurant.StartupActivity
    public boolean onCreateOptionsMenu(Menu menu) {
                                       ^
StartupActivity.java:74: cannot find symbol
symbol  : class MenuItem
location: class com.yellowbrickcode.restaurant.StartupActivity
    public boolean onOptionsItemSelected(MenuItem item) {
                                         ^
StartupActivity.java:80: cannot find symbol
symbol  : class Bundle
location: class com.yellowbrickcode.restaurant.StartupActivity
    protected void onCreate(Bundle savedInstanceState) {
                            ^
PushService.java:14: package org.json does not exist
import org.json.JSONException;
               ^
PushService.java:16: package android.app does not exist
import android.app.AlarmManager;
                  ^
PushService.java:17: package android.app does not exist
import android.app.IntentService;
                  ^
PushService.java:18: package android.app does not exist
import android.app.Notification;
                  ^
PushService.java:19: package android.app does not exist
import android.app.NotificationManager;
                  ^
PushService.java:20: package android.app does not exist
import android.app.PendingIntent;
                  ^
PushService.java:21: package android.content does not exist
import android.content.BroadcastReceiver;
                      ^
PushService.java:22: package android.content does not exist
import android.content.Context;
                      ^
PushService.java:23: package android.content does not exist
import android.content.Intent;
                      ^
PushService.java:24: package android.content does not exist
import android.content.SharedPreferences;
                      ^
PushService.java:25: package android.content.SharedPreferences does not exist
import android.content.SharedPreferences.Editor;
                                        ^
PushService.java:26: package android.os does not exist
import android.os.Binder;
                 ^
PushService.java:27: package android.os does not exist
import android.os.IBinder;
                 ^
PushService.java:28: package android.os does not exist
import android.os.SystemClock;
                 ^
PushService.java:29: package android.preference does not exist
import android.preference.PreferenceManager;
                         ^
PushService.java:30: package android.util does not exist
import android.util.Log;
                   ^
RemoteUpdater.java:13: package org.json does not exist
import org.json.JSONArray;
               ^
RemoteUpdater.java:14: package org.json does not exist
import org.json.JSONException;
               ^
RemoteUpdater.java:15: package org.json does not exist
import org.json.JSONObject;
               ^
RemoteUpdater.java:17: package android.content does not exist
import android.content.ContentResolver;
                      ^
RemoteUpdater.java:18: package android.content does not exist
import android.content.ContentValues;
                      ^
RemoteUpdater.java:20: package android.database does not exist
import android.database.Cursor;
                       ^
RemoteUpdater.java:21: package android.database does not exist
import android.database.SQLException;
                       ^
RemoteUpdater.java:23: package android.net does not exist
import android.net.Uri;
                  ^
RemoteUpdater.java:24: package android.util does not exist
import android.util.Log;
                   ^
PushService.java:54: cannot find symbol
symbol: class IntentService
public class PushService extends IntentService implements Saveable {
                                 ^
PushService.java:681: cannot find symbol
symbol  : class Binder
location: class com.yellowbrickcode.restaurant.c2dm.PushService
    protected class PushBinder extends Binder {
                                       ^
PushService.java:178: cannot find symbol
symbol  : class Context
location: class com.yellowbrickcode.restaurant.c2dm.PushService
    public boolean clear(Context ctx) {
                         ^
PushService.java:190: cannot find symbol
symbol  : class Intent
location: class com.yellowbrickcode.restaurant.c2dm.PushService
    public IBinder onBind(Intent intent) {
                          ^
PushService.java:190: cannot find symbol
symbol  : class IBinder
location: class com.yellowbrickcode.restaurant.c2dm.PushService
    public IBinder onBind(Intent intent) {
           ^
PushService.java:205: cannot find symbol
symbol  : class Context
location: class com.yellowbrickcode.restaurant.c2dm.PushService
    public boolean restore(Context ctx) {
                           ^
PushService.java:228: cannot find symbol
symbol  : class Context
location: class com.yellowbrickcode.restaurant.c2dm.PushService
    public boolean save(Context ctx) {
                        ^
PushService.java:254: cannot find symbol
symbol  : class Intent
location: class com.yellowbrickcode.restaurant.c2dm.PushService
    protected void onHandleIntent(Intent intent) {
                                  ^
PushService.java:357: cannot find symbol
symbol  : class Intent
location: class com.yellowbrickcode.restaurant.c2dm.PushService
    private void receiveMessage(Intent intent) {
                                ^
PushService.java:393: cannot find symbol
symbol  : class Intent
location: class com.yellowbrickcode.restaurant.c2dm.PushService
    private void receiveRegistration(Intent intent) throws JSONException {
                                     ^
PushService.java:393: cannot find symbol
symbol  : class JSONException
location: class com.yellowbrickcode.restaurant.c2dm.PushService
    private void receiveRegistration(Intent intent) throws JSONException {
                                                           ^
PushService.java:416: cannot find symbol
symbol  : class Intent
location: class com.yellowbrickcode.restaurant.c2dm.PushService
    private void register(Intent intent) {
                          ^
PushService.java:456: cannot find symbol
symbol  : class Intent
location: class com.yellowbrickcode.restaurant.c2dm.PushService
    private void retryAction(Intent intent) {
                             ^
PushService.java:498: cannot find symbol
symbol  : class JSONException
location: class com.yellowbrickcode.restaurant.c2dm.PushService
    private void unregister() throws JSONException{
                                     ^
PushService.java:523: cannot find symbol
symbol  : class JSONException
location: class com.yellowbrickcode.restaurant.c2dm.PushService
    private void unregisterServer(String regId) throws JSONException{
                                                       ^
PushService.java:545: cannot find symbol
symbol  : class Intent
location: class com.yellowbrickcode.restaurant.c2dm.PushService
    private void updateRegistration(Intent intent) throws JSONException {
                                    ^
PushService.java:545: cannot find symbol
symbol  : class JSONException
location: class com.yellowbrickcode.restaurant.c2dm.PushService
    private void updateRegistration(Intent intent) throws JSONException {
                                                          ^
RemoteUpdater.java:72: cannot find symbol
symbol  : class ContentValues
location: class com.yellowbrickcode.restaurant.c2dm.RemoteUpdater
    private ArrayList<ContentValues> mInsertedRecords;
                      ^
RemoteUpdater.java:77: cannot find symbol
symbol  : class ContentValues
location: class com.yellowbrickcode.restaurant.c2dm.RemoteUpdater
    private ArrayList<ContentValues> mInsertedMappings;
                      ^
RemoteUpdater.java:86: cannot find symbol
symbol  : class ContentResolver
location: class com.yellowbrickcode.restaurant.c2dm.RemoteUpdater
    private ContentResolver mResolver;
            ^
RemoteUpdater.java:97: cannot find symbol
symbol  : class ContentResolver
location: class com.yellowbrickcode.restaurant.c2dm.RemoteUpdater
    public RemoteUpdater(String authority, ContentResolver resolver) {
                                           ^
RemoteUpdater.java:192: cannot find symbol
symbol  : class JSONObject
location: class com.yellowbrickcode.restaurant.c2dm.RemoteUpdater
    private boolean updateNewsFeed(JSONObject serverData) {
                                   ^
RemoteUpdater.java:207: cannot find symbol
symbol  : class JSONObject
location: class com.yellowbrickcode.restaurant.c2dm.RemoteUpdater
    private boolean updateTable(JSONObject serverData, Uri authority,
                                ^
RemoteUpdater.java:207: cannot find symbol
symbol  : class Uri
location: class com.yellowbrickcode.restaurant.c2dm.RemoteUpdater
    private boolean updateTable(JSONObject serverData, Uri authority,
                                                       ^
RemoteUpdater.java:208: cannot find symbol
symbol  : class JSONException
location: class com.yellowbrickcode.restaurant.c2dm.RemoteUpdater
            String table, String date) throws JSONException {
                                              ^
RemoteUpdater.java:234: cannot find symbol
symbol  : class JSONObject
location: class com.yellowbrickcode.restaurant.c2dm.RemoteUpdater
    private boolean updateMenu(JSONObject serverData) {
                               ^
RemoteUpdater.java:308: cannot find symbol
symbol  : class Uri
location: class com.yellowbrickcode.restaurant.c2dm.RemoteUpdater
    private boolean commitUpdates(Uri authority, String table, String date) {
                                  ^
RemoteUpdater.java:365: cannot find symbol
symbol  : class JSONArray
location: class com.yellowbrickcode.restaurant.c2dm.RemoteUpdater
    private void parseRecords(JSONArray records, boolean delete)
                              ^
RemoteUpdater.java:366: cannot find symbol
symbol  : class JSONException
location: class com.yellowbrickcode.restaurant.c2dm.RemoteUpdater
            throws JSONException {
                   ^
PushService.java:612: cannot find symbol
symbol  : class BroadcastReceiver
location: class com.yellowbrickcode.restaurant.c2dm.PushService
    public static class Receiver extends BroadcastReceiver {
                                         ^
PushService.java:629: cannot find symbol
symbol  : class Context
location: class com.yellowbrickcode.restaurant.c2dm.PushService.Receiver
        public void onReceive(Context context, Intent intent) {
                              ^
PushService.java:629: cannot find symbol
symbol  : class Intent
location: class com.yellowbrickcode.restaurant.c2dm.PushService.Receiver
        public void onReceive(Context context, Intent intent) {
                                               ^
SyncPreferences.java:10: package android.os does not exist
import android.os.Bundle;
                 ^
SyncPreferences.java:11: package android.preference does not exist
import android.preference.PreferenceActivity;
                         ^
SyncPreferences.java:23: cannot find symbol
symbol: class PreferenceActivity
public class SyncPreferences extends PreferenceActivity {
                                     ^
SyncPreferences.java:27: cannot find symbol
symbol  : class Bundle
location: class com.yellowbrickcode.restaurant.c2dm.SyncPreferences
    protected void onCreate(Bundle savedInstanceState) {
                            ^
Provider.java:5: package android.content does not exist
import android.content.ContentProvider;
                      ^
Provider.java:6: package android.content does not exist
import android.content.ContentValues;
                      ^
Provider.java:7: package android.content does not exist
import android.content.UriMatcher;
                      ^
Provider.java:8: package android.database does not exist
import android.database.Cursor;
                       ^
Provider.java:9: package android.database.sqlite does not exist
import android.database.sqlite.SQLiteDatabase;
                              ^
Provider.java:10: package android.graphics.drawable does not exist
import android.graphics.drawable.Drawable;
                                ^
Provider.java:11: package android.net does not exist
import android.net.Uri;
                  ^
Provider.java:12: package android.util does not exist
import android.util.Log;
                   ^
Provider.java:41: cannot find symbol
symbol: class ContentProvider
public class Provider extends ContentProvider {
                              ^
Provider.java:51: cannot find symbol
symbol  : class Uri
location: class com.yellowbrickcode.restaurant.database.Provider
    public static final Uri CONTENT_URI = 
                        ^
Provider.java:57: cannot find symbol
symbol  : class Uri
location: class com.yellowbrickcode.restaurant.database.Provider
    public static final Uri MENU_URI = Uri.withAppendedPath(CONTENT_URI, UpdateType.menu.toString());
                        ^
Provider.java:62: cannot find symbol
symbol  : class Uri
location: class com.yellowbrickcode.restaurant.database.Provider
    public static final Uri NEWS_FEED_URI = Uri.withAppendedPath(CONTENT_URI, Table.NEWS_FEED.name);
                        ^
Provider.java:65: cannot find symbol
symbol  : class Uri
location: class com.yellowbrickcode.restaurant.database.Provider
    public static final Uri UPDATES_URI = Uri.withAppendedPath(CONTENT_URI, Table.UPDATE_LOG.name);
                        ^
Provider.java:70: cannot find symbol
symbol  : class Uri
location: class com.yellowbrickcode.restaurant.database.Provider
    public static final Uri IMAGE_URI =  Uri.withAppendedPath(CONTENT_URI, Table.IMAGE.name);
                        ^
Provider.java:80: cannot find symbol
symbol  : class UriMatcher
location: class com.yellowbrickcode.restaurant.database.Provider
    private static final UriMatcher URI_MATCHER;
                         ^
DatabaseHelper.java:3: package android.content does not exist
import android.content.ContentValues;
                      ^
DatabaseHelper.java:5: package android.database.sqlite does not exist
import android.database.sqlite.SQLiteDatabase;
                              ^
DatabaseHelper.java:6: package android.database.sqlite does not exist
import android.database.sqlite.SQLiteOpenHelper;
                              ^
DatabaseHelper.java:7: package android.graphics does not exist
import android.graphics.Bitmap;
                       ^
DatabaseHelper.java:8: package android.util does not exist
import android.util.Log;
                   ^
DatabaseHelper.java:21: cannot find symbol
symbol: class SQLiteOpenHelper
public class DatabaseHelper extends SQLiteOpenHelper {
                                    ^
Standard Doclet version 1.6.0_23
Building tree for all the packages and classes...
java.lang.NullPointerException
    at com.sun.tools.javadoc.TypeMaker.getType(TypeMaker.java:85)
    at com.sun.tools.javadoc.TypeMaker.getType(TypeMaker.java:47)
    at com.sun.tools.javadoc.ClassDocImpl.superclassType(ClassDocImpl.java:486)
    at com.sun.tools.doclets.internal.toolkit.util.Util.getAllInterfaces(Util.java:405)
    at com.sun.tools.doclets.internal.toolkit.util.Util.getAllInterfaces(Util.java:443)
    at com.sun.tools.doclets.internal.toolkit.util.ClassTree.processType(ClassTree.java:180)
    at com.sun.tools.doclets.internal.toolkit.util.ClassTree.buildTree(ClassTree.java:132)
    at com.sun.tools.doclets.internal.toolkit.util.ClassTree.<init>(ClassTree.java:91)
    at com.sun.tools.doclets.internal.toolkit.AbstractDoclet.startGeneration(AbstractDoclet.java:123)
    at com.sun.tools.doclets.internal.toolkit.AbstractDoclet.start(AbstractDoclet.java:83)
    at com.sun.tools.doclets.formats.html.HtmlDoclet.start(HtmlDoclet.java:63)
    at com.sun.tools.doclets.standard.Standard.start(Standard.java:41)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:616)
    at com.sun.tools.javadoc.DocletInvoker.invoke(DocletInvoker.java:291)
    at com.sun.tools.javadoc.DocletInvoker.start(DocletInvoker.java:165)
    at com.sun.tools.javadoc.Start.parseAndExecute(Start.java:374)
    at com.sun.tools.javadoc.Start.begin(Start.java:162)
    at com.sun.tools.javadoc.Main.execute(Main.java:59)
    at com.sun.tools.javadoc.Main.main(Main.java:49)
100 warnings

The key problem is the error at the bottom. - The 100 warnings only involve linking to the main Android library documentation, which is a separate issue that does not cause the error without reference to android.support. In fact, none of the warnings say anything resembling "package android.support does not exist". This leads me to believe the javadoc is finding the compatibility library, but that something involving the jar or the way I reference it is causing an error when it comes to final javadoc generation.

Any ideas about what might be causing the error are appreciated.

Answer 1

I had the same error. By selecting different parts of the project in the wizard the error would sometimes trigger and sometimes not.

Anyway, before that error there's a lot of "package android.* does not exist" warnings, so I decided to get rid of these first. Here's the workaround that worked for me.

Now, with these warning messages gone, the NullPointerException disappeared too! I was able to generate javadoc for the entire project, including links to referenced library projects, 3rd party library jars and Android framework classes.

Answer 2

I was having a similar problem and if i unchecked everything except src, the error went away.

Answer 3

I had the same callstack with a completely different set of java files and libraries. The error went away after I completed the classpath to include all base classes, base interfaces and other classes that where referenced from the javadoc. So fixing all the "cannot find symbol" warnings fixed the callstack as well.