Top 500 Java Classes

This is the index of popular classes provided by Java Stand Library, Eclipse, Apache, Spring, Android, etc. The number in "( )" indicates their popularity which scales from 1 - 3000. The numbers are based on a random sample of 3000 open source projects.

1. java.util.List (2889)
2. java.util.ArrayList (2831)
3. java.io.IOException (2813)
4. java.util.Map (2592)
5. java.util.HashMap (2541)
6. java.io.File (2195)
7. java.io.InputStream (2125)
8. java.util.Arrays (2068)
9. java.util.Collections (2028)
10. java.util.Set (2019)
11. java.util.Iterator (1954)
12. java.util.Collection (1734)
13. java.util.HashSet (1721)
14. java.util.Date (1679)
15. java.net.URL (1548)
16. java.io.FileInputStream (1495)
17. org.junit.Test (1463)
18. java.io.BufferedReader (1432)
19. java.io.OutputStream (1391)
20. java.io.InputStreamReader (1389)
21. java.io.FileOutputStream (1378)
22. java.util.regex.Pattern (1314)
23. java.io.FileNotFoundException (1294)
24. java.io.Serializable (1257)
25. java.lang.reflect.Method (1229)
26. java.io.ByteArrayOutputStream (1206)
27. java.util.LinkedList (1194)
28. java.util.Properties (1157)
29. java.text.SimpleDateFormat (1103)
30. java.io.ByteArrayInputStream (1079)
31. java.util.regex.Matcher (1064)
32. java.io.UnsupportedEncodingException (1047)
33. java.util.Locale (1009)
34. java.util.Comparator (1007)
35. org.junit.Before (1005)
36. java.util.Enumeration (949)
37. java.io.PrintWriter (931)
38. java.util.Random (928)
39. java.lang.reflect.InvocationTargetException (918)
40. java.net.MalformedURLException (916)
41. java.util.Map.Entry (899)
42. java.util.Calendar (859)
43. java.io.StringWriter (819)
44. java.lang.reflect.Field (790)
45. java.util.LinkedHashMap (788)
46. java.net.URI (781)
47. junit.framework.TestCase (720)
48. java.io.Reader (717)
49. java.io.Writer (706)
50. java.util.concurrent.TimeUnit (699)
51. java.io.FileReader (691)
52. java.io.FileWriter (682)
53. java.io.StringReader (680)
54. java.util.logging.Logger (677)
55. java.lang.reflect.Constructor (664)
56. java.text.ParseException (649)
57. java.net.URISyntaxException (644)
58. javax.servlet.http.HttpServletRequest (636)
59. java.lang.annotation.Retention (635)
60. java.util.TreeSet (632)
61. org.slf4j.Logger (627)
62. java.util.concurrent.ConcurrentHashMap (625)
63. java.io.OutputStreamWriter (622)
64. java.util.TreeMap (621)
65. java.util.StringTokenizer (619)
66. org.slf4j.LoggerFactory (618)
67. java.text.DateFormat (607)
68. org.junit.After (605)
69. android.os.Bundle (605)
70. android.content.Context (603)
71. javax.servlet.http.HttpServletResponse (603)
72. java.io.BufferedInputStream (600)
73. java.security.NoSuchAlgorithmException (592)
74. java.util.logging.Level (589)
75. java.lang.annotation.Target (588)
76. java.util.concurrent.Executors (588)
77. org.xml.sax.SAXException (586)
78. java.util.Vector (583)
79. android.util.Log (583)
80. android.content.Intent (578)
81. org.junit.runner.RunWith (577)
82. android.app.Activity (575)
83. javax.servlet.ServletException (568)
84. android.view.View (567)
85. java.util.Hashtable (559)
86. java.lang.annotation.RetentionPolicy (559)
87. java.security.MessageDigest (553)
88. junit.framework.Assert (548)
89. org.junit.Assert (548)
90. java.io.PrintStream (546)
91. java.net.InetAddress (537)
92. java.util.UUID (526)
93. android.widget.TextView (524)
94. org.w3c.dom.Document (521)
95. java.net.URLEncoder (521)
96. java.lang.annotation.ElementType (520)
97. java.net.UnknownHostException (518)
98. java.nio.charset.Charset (516)
99. java.io.BufferedWriter (513)
100. java.util.concurrent.ExecutorService (503)
101. javax.xml.parsers.DocumentBuilderFactory (487)
102. java.nio.ByteBuffer (481)
103. java.io.ObjectInputStream (481)
104. java.io.ObjectOutputStream (467)
105. java.util.concurrent.atomic.AtomicInteger (467)
106. android.widget.Toast (466)
107. java.util.NoSuchElementException (466)
108. org.w3c.dom.Element (463)
109. java.io.BufferedOutputStream (461)
110. java.util.LinkedHashSet (461)
111. java.math.BigInteger (459)
112. android.os.Handler (451)
113. org.junit.BeforeClass (450)
114. android.content.SharedPreferences (449)
115. android.content.DialogInterface (449)
116. android.view.ViewGroup (444)
117. java.math.BigDecimal (443)
118. java.lang.reflect.Modifier (441)
119. android.net.Uri (437)
120. javax.xml.parsers.ParserConfigurationException (437)
121. java.net.Socket (436)
122. android.app.AlertDialog (436)
123. android.widget.Button (428)
124. java.util.Stack (428)
125. org.w3c.dom.NodeList (428)
126. javax.xml.parsers.DocumentBuilder (427)
127. java.net.URLConnection (426)
128. android.view.LayoutInflater (423)
129. org.w3c.dom.Node (422)
130. java.util.TimeZone (422)
131. java.sql.SQLException (421)
132. android.widget.ListView (406)
133. org.xml.sax.InputSource (405)
134. org.apache.log4j.Logger (398)
135. android.view.MenuItem (394)
136. android.widget.ImageView (394)
137. org.apache.http.HttpResponse (389)
138. org.apache.http.impl.client.DefaultHttpClient (388)
139. java.net.HttpURLConnection (387)
140. org.junit.Ignore (386)
141. java.net.InetSocketAddress (385)
142. android.util.AttributeSet (383)
143. java.lang.reflect.Array (383)
144. android.view.View.OnClickListener (380)
145. android.widget.AdapterView (376)
146. android.widget.EditText (374)
147. android.view.Menu (374)
148. android.database.Cursor (374)
149. android.graphics.Bitmap (372)
150. java.io.DataInputStream (366)
151. java.io.DataOutputStream (362)
152. java.util.zip.ZipEntry (357)
153. android.widget.LinearLayout (354)
154. javax.servlet.http.HttpServlet (352)
155. java.text.DecimalFormat (350)
156. java.util.concurrent.Callable (350)
157. org.apache.commons.lang.StringUtils (349)
158. java.io.FilenameFilter (346)
159. java.util.GregorianCalendar (346)
160. java.text.MessageFormat (344)
161. java.awt.Color (340)
162. android.view.KeyEvent (337)
163. java.net.URLDecoder (336)
164. java.lang.annotation.Annotation (336)
165. java.util.concurrent.Future (335)
166. android.graphics.drawable.Drawable (332)
167. android.content.res.Resources (331)
168. java.util.concurrent.atomic.AtomicBoolean (329)
169. android.preference.PreferenceManager (328)
170. android.widget.ArrayAdapter (327)
171. android.view.MotionEvent (326)
172. org.apache.commons.logging.Log (325)
173. java.util.ResourceBundle (324)
174. android.app.Dialog (324)
175. org.apache.commons.logging.LogFactory (321)
176. java.lang.ref.WeakReference (320)
177. java.util.concurrent.ExecutionException (320)
178. android.graphics.Canvas (319)
179. java.sql.ResultSet (319)
180. org.apache.http.client.methods.HttpGet (317)
181. android.os.AsyncTask (317)
182. java.sql.Connection (317)
183. java.util.Queue (315)
184. java.io.Closeable (313)
185. java.util.ListIterator (311)
186. android.content.ContentValues (311)
187. android.content.BroadcastReceiver (307)
188. org.apache.commons.io.IOUtils (305)
189. android.content.pm.PackageManager (301)
190. android.preference.PreferenceActivity (299)
191. org.junit.AfterClass (299)
192. android.os.Message (296)
193. android.graphics.Color (295)
194. java.net.ServerSocket (295)
195. org.json.JSONObject (294)
196. org.apache.http.client.HttpClient (292)
197. java.util.TimerTask (291)
198. java.util.concurrent.CountDownLatch (289)
199. android.app.ProgressDialog (287)
200. java.awt.event.ActionEvent (287)
201. javax.servlet.ServletContext (285)
202. android.view.Window (285)
203. java.util.Timer (285)
204. android.graphics.BitmapFactory (281)
205. android.database.sqlite.SQLiteDatabase (278)
206. android.os.IBinder (276)
207. java.awt.image.BufferedImage (276)
208. java.lang.reflect.Type (275)
209. java.util.SortedSet (274)
210. android.content.ComponentName (273)
211. java.text.NumberFormat (272)
212. android.app.PendingIntent (271)
213. org.osgi.framework.BundleContext (269)
214. java.awt.event.ActionListener (269)
215. android.text.TextUtils (267)
216. java.util.concurrent.LinkedBlockingQueue (267)
217. java.util.concurrent.atomic.AtomicLong (267)
218. org.json.JSONException (265)
219. org.apache.commons.io.FileUtils (264)
220. org.apache.http.HttpEntity (263)
221. javax.servlet.ServletRequest (263)
222. android.widget.BaseAdapter (263)
223. android.os.Build (263)
224. java.util.zip.GZIPInputStream (260)
225. java.awt.Dimension (259)
226. org.xml.sax.Attributes (258)
227. android.os.Environment (257)
228. android.widget.AdapterView.OnItemClickListener (257)
229. java.util.concurrent.CopyOnWriteArrayList (256)
230. java.io.FileFilter (255)
231. javax.xml.transform.stream.StreamResult (255)
232. android.app.Service (253)
233. android.app.ListActivity (252)
234. android.view.Gravity (251)
235. javax.swing.JPanel (251)
236. javax.swing.JFrame (250)
237. android.database.sqlite.SQLiteOpenHelper (249)
238. javax.servlet.ServletResponse (249)
239. java.security.SecureRandom (248)
240. android.graphics.Rect (247)
241. junit.framework.Test (246)
242. android.graphics.Paint (245)
243. java.net.URLClassLoader (245)
244. junit.framework.TestSuite (245)
245. org.apache.http.client.methods.HttpPost (244)
246. java.util.concurrent.BlockingQueue (243)
247. java.util.concurrent.ConcurrentMap (242)
248. android.content.pm.PackageManager.NameNotFoundException (241)
249. javax.imageio.ImageIO (241)
250. java.util.EnumSet (238)
251. java.util.concurrent.locks.ReentrantLock (236)
252. java.nio.channels.FileChannel (236)
253. javax.xml.transform.TransformerFactory (236)
254. java.sql.PreparedStatement (234)
255. android.content.ContentResolver (234)
256. android.view.WindowManager (234)
257. org.json.JSONArray (234)
258. android.content.IntentFilter (233)
259. java.util.WeakHashMap (233)
260. javax.inject.Inject (233)
261. java.net.SocketException (232)
262. javax.swing.JLabel (232)
263. javax.xml.transform.Transformer (231)
264. android.view.ContextMenu (229)
265. javax.servlet.http.HttpSession (228)
266. java.lang.reflect.Proxy (228)
267. java.io.EOFException (227)
268. java.sql.Statement (226)
269. android.widget.ImageButton (222)
270. android.content.res.Configuration (220)
271. java.io.RandomAccessFile (220)
272. javax.sql.DataSource (219)
273. android.widget.CheckBox (217)
274. com.google.common.collect.Lists (216)
275. android.app.Application (215)
276. java.util.concurrent.atomic.AtomicReference (214)
277. org.xml.sax.helpers.DefaultHandler (214)
278. android.preference.Preference (213)
279. javax.xml.transform.dom.DOMSource (213)
280. javax.persistence.Entity (213)
281. javax.swing.JOptionPane (212)
282. org.codehaus.jackson.map.ObjectMapper (212)
283. android.os.SystemClock (212)
284. android.app.Notification (212)
285. java.lang.reflect.InvocationHandler (211)
286. org.springframework.beans.factory.annotation.Autowired (211)
287. javax.servlet.FilterChain (210)
288. java.util.SortedMap (209)
289. android.app.NotificationManager (207)
290. android.os.Parcelable (207)
291. org.springframework.context.ApplicationContext (204)
292. javax.persistence.Id (203)
293. java.awt.BorderLayout (203)
294. android.view.MenuInflater (203)
295. java.awt.event.MouseEvent (202)
296. android.widget.ProgressBar (202)
297. java.sql.DriverManager (201)
298. org.apache.http.params.HttpParams (201)
299. java.util.jar.JarFile (200)
300. android.graphics.Typeface (200)
301. java.util.concurrent.ThreadFactory (199)
302. java.awt.Component (196)
303. android.graphics.drawable.BitmapDrawable (195)
304. java.lang.reflect.ParameterizedType (194)
305. java.util.concurrent.Executor (194)
306. javax.swing.JButton (192)
307. javax.servlet.Filter (192)
308. javax.servlet.FilterConfig (192)
309. android.content.pm.PackageInfo (191)
310. java.util.concurrent.TimeoutException (190)
311. android.widget.FrameLayout (188)
312. org.apache.commons.codec.binary.Base64 (188)
313. java.util.Scanner (188)
314. java.util.zip.ZipFile (187)
315. java.util.jar.JarEntry (187)
316. java.awt.Graphics2D (186)
317. java.awt.Font (186)
318. java.lang.ref.SoftReference (185)
319. java.awt.Graphics (185)
320. java.security.Principal (184)
321. java.security.cert.X509Certificate (184)
322. javax.naming.NamingException (184)
323. android.webkit.WebView (183)
324. android.view.animation.Animation (183)
325. java.util.concurrent.locks.Lock (181)
326. javax.xml.parsers.SAXParserFactory (181)
327. android.content.res.TypedArray (181)
328. javax.swing.JScrollPane (181)
329. org.testng.annotations.Test (180)
330. java.util.concurrent.ScheduledExecutorService (179)
331. java.util.MissingResourceException (178)
332. com.google.common.collect.Maps (178)
333. javax.xml.transform.TransformerException (178)
334. android.view.ContextMenu.ContextMenuInfo (178)
335. android.widget.CompoundButton (177)
336. android.content.ActivityNotFoundException (177)
337. android.os.Parcel (176)
338. javax.net.ssl.SSLContext (175)
339. org.apache.http.Header (174)
340. android.view.animation.AnimationUtils (174)
341. android.content.pm.ResolveInfo (172)
342. java.sql.Timestamp (171)
343. java.security.AccessController (171)
344. java.security.cert.CertificateException (171)
345. java.awt.event.WindowEvent (171)
346. android.content.SharedPreferences.Editor (170)
347. org.w3c.dom.NamedNodeMap (169)
348. java.awt.event.KeyEvent (169)
349. android.view.ViewGroup.LayoutParams (169)
350. android.graphics.RectF (169)
351. javax.servlet.http.Cookie (168)
352. org.xmlpull.v1.XmlPullParserException (168)
353. java.lang.management.ManagementFactory (168)
354. org.xmlpull.v1.XmlPullParser (166)
355. android.os.Looper (166)
356. javax.xml.bind.annotation.XmlRootElement (166)
357. java.util.concurrent.locks.ReentrantReadWriteLock (166)
358. java.util.concurrent.ConcurrentLinkedQueue (164)
359. javax.swing.JTextField (164)
360. android.widget.ListAdapter (164)
361. javax.servlet.ServletConfig (163)
362. java.util.concurrent.ThreadPoolExecutor (163)
363. java.util.BitSet (163)
364. javax.xml.parsers.SAXParser (163)
365. java.util.zip.ZipInputStream (162)
366. android.net.ConnectivityManager (162)
367. java.beans.PropertyChangeListener (161)
368. org.osgi.framework.Bundle (159)
369. javax.naming.InitialContext (159)
370. javax.persistence.EntityManager (158)
371. org.apache.http.params.BasicHttpParams (158)
372. java.awt.Image (158)
373. java.nio.CharBuffer (157)
374. java.util.zip.ZipOutputStream (157)
375. java.beans.PropertyDescriptor (157)
376. javax.swing.ImageIcon (157)
377. java.security.PrivilegedAction (157)
378. javax.management.ObjectName (153)
379. com.google.common.base.Function (153)
380. javax.xml.bind.JAXBContext (153)
381. android.content.DialogInterface.OnClickListener (152)
382. android.widget.Spinner (152)
383. org.apache.http.client.ClientProtocolException (152)
384. javax.xml.namespace.QName (151)
385. javax.persistence.GeneratedValue (151)
386. javax.swing.SwingUtilities (151)
387. org.eclipse.swt.SWT (150)
388. android.text.Editable (150)
389. android.os.RemoteException (150)
390. android.content.ContentProvider (149)
391. org.springframework.core.io.Resource (149)
392. android.graphics.Matrix (149)
393. org.mockito.Mockito (149)
394. org.eclipse.swt.widgets.Composite (149)
395. android.widget.RelativeLayout (148)
396. javax.servlet.ServletOutputStream (148)
397. org.apache.http.message.BasicNameValuePair (147)
398. com.google.common.collect.Sets (147)
399. java.util.EventListener (147)
400. javax.xml.transform.OutputKeys (146)
401. java.awt.Point (146)
402. java.beans.PropertyChangeEvent (146)
403. android.provider.BaseColumns (145)
404. javax.swing.JComponent (145)
405. javax.persistence.Column (144)
406. javax.swing.BorderFactory (144)
407. org.joda.time.DateTime (144)
408. org.apache.http.NameValuePair (144)
409. org.apache.http.util.EntityUtils (143)
410. javax.ws.rs.Path (143)
411. javax.annotation.PostConstruct (143)
412. java.io.DataInput (143)
413. org.xml.sax.XMLReader (143)
414. org.apache.http.params.HttpConnectionParams (142)
415. javax.xml.bind.annotation.XmlElement (142)
416. org.junit.Rule (142)
417. org.apache.commons.httpclient.HttpClient (142)
418. javax.xml.transform.stream.StreamSource (141)
419. android.util.DisplayMetrics (141)
420. android.content.pm.ActivityInfo (140)
421. android.media.AudioManager (140)
422. java.security.KeyStore (139)
423. org.eclipse.ui.plugin.AbstractUIPlugin (139)
424. com.google.common.base.Preconditions (139)
425. org.springframework.test.context.ContextConfiguration (139)
426. javax.net.ssl.TrustManager (139)
427. com.google.inject.Inject (139)
428. org.osgi.framework.BundleActivator (138)
429. org.apache.hadoop.conf.Configuration (138)
430. android.util.TypedValue (138)
431. android.view.ViewConfiguration (138)
432. android.database.SQLException (138)
433. javax.naming.Context (138)
434. javax.servlet.ServletContextEvent (138)
435. java.io.FilterInputStream (138)
436. android.content.ContentUris (137)
437. java.awt.Rectangle (137)
438. javax.ws.rs.GET (137)
439. org.springframework.context.support.ClassPathXmlApplicationContext (137)
440. org.apache.http.conn.scheme.Scheme (136)
441. org.apache.log4j.Level (135)
442. org.eclipse.swt.layout.GridData (135)
443. javax.swing.JTextArea (135)
444. org.eclipse.core.runtime.IProgressMonitor (135)
445. org.apache.http.client.entity.UrlEncodedFormEntity (135)
446. android.text.TextWatcher (135)
447. java.net.SocketTimeoutException (134)
448. java.util.EventObject (134)
449. org.eclipse.swt.widgets.Display (134)
450. android.text.Html (134)
451. java.util.zip.GZIPOutputStream (134)
452. org.eclipse.core.runtime.CoreException (133)
453. javax.net.ssl.X509TrustManager (133)
454. javax.ws.rs.core.MediaType (133)
455. com.google.common.base.Predicate (132)
456. javax.crypto.spec.SecretKeySpec (132)
457. android.content.ServiceConnection (132)
458. java.util.concurrent.ArrayBlockingQueue (132)
459. org.apache.http.HttpStatus (131)
460. javax.swing.JFileChooser (131)
461. javax.ws.rs.Produces (130)
462. org.xml.sax.SAXParseException (130)
463. java.awt.Insets (130)
464. android.os.PowerManager (130)
465. javax.swing.UIManager (129)
466. javax.management.MBeanServer (129)
467. org.eclipse.swt.layout.GridLayout (129)
468. org.eclipse.swt.widgets.Label (128)
469. java.nio.ByteOrder (128)
470. java.awt.Toolkit (128)
471. java.io.DataOutput (128)
472. org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager (128)
473. javax.crypto.Cipher (128)
474. org.apache.http.protocol.HttpContext (128)
475. android.net.NetworkInfo (127)
476. com.google.inject.Injector (127)
477. java.awt.event.WindowAdapter (127)
478. org.apache.http.conn.scheme.SchemeRegistry (126)
479. android.content.UriMatcher (126)
480. org.eclipse.swt.events.SelectionEvent (126)
481. org.springframework.beans.factory.InitializingBean (125)
482. android.widget.AbsListView (125)
483. android.view.inputmethod.InputMethodManager (125)
484. java.awt.event.MouseAdapter (125)
485. javax.xml.bind.JAXBException (124)
486. org.eclipse.core.runtime.IStatus (124)
487. org.mockito.Mock (124)
488. java.beans.Introspector (123)
489. android.preference.ListPreference (123)
490. android.support.v4.app.Fragment (123)
491. org.eclipse.core.runtime.Status (123)
492. javax.swing.JMenuItem (123)
493. java.net.ConnectException (123)
494. org.springframework.stereotype.Controller (123)
495. org.osgi.framework.ServiceReference (123)
496. android.content.pm.ApplicationInfo (123)
497. javax.xml.transform.Source (123)
498. com.google.gson.Gson (122)
499. java.awt.Container (122)
500. javax.xml.xpath.XPathFactory (122)