Eclipse 中 Android 项目的 Javadoc 因 NullPointerException 而失败

Javadoc for Android project in Eclipse fails with NullPointerException

提问by Travis YBC

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.

我正在尝试在 Eclipse 中为我的 Android 项目生成 javadoc 注释，但我不断收到 NullPointerException。只有当我尝试为导入Android 兼容库(android.support) 的类生成 javadoc 时，才会出现问题，我已将其作为外部 jar 附加。我还参考了 Android 2.2 和几个库项目，但它们本身不会导致此错误。

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 notcause 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.

关键问题是底部的错误。- 100 条警告只涉及到主要 Android 库文档的链接，这是一个单独的问题，不参考 android.support不会导致错误。事实上，没有一个警告说任何类似于“包 android.support 不存在”的内容。这让我相信 javadoc 正在寻找兼容性库，但是当涉及到最终的 javadoc 生成时，涉及 jar 或我引用它的方式会导致错误。

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

任何关于可能导致错误的想法都表示赞赏。

采纳答案by Pēteris Caune

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

我有同样的错误。通过在向导中选择项目的不同部分，错误有时会触发，有时不会。

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 workaroundthat worked for me.

无论如何，在那个错误之前有很多“package android.*不存在”的警告，所以我决定首先摆脱这些。这是对我有用的解决方法。

Now, with these warning messages gone, the NullPointerExceptiondisappeared 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.

现在，随着这些警告信息消失，也NullPointerException消失了！我能够为整个项目生成 javadoc，包括指向引用库项目、第 3 方库 jar 和 Android 框架类的链接。

回答by prolink007

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

我遇到了类似的问题，如果我取消选中除 之外src的所有内容，错误就会消失。

回答by Alex.

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.

我有相同的调用堆栈和一组完全不同的 java 文件和库。在我完成类路径以包含从 javadoc 引用的所有基类、基接口和其他类后，错误消失了。因此，修复所有“找不到符号”警告也修复了调用堆栈。