The Most Popular Java API Classes

This is the index page of the most commonly used Java API classes. The number in "( )" indicates their popularity which scales from 1 - 50,000. The numbers are based on a random sample of 50,000 open source projects. The following only shows the top 10,000. You may use the search function to view more.

1. java.util.List

(26331)

28 commonly used methods/fields.
2. java.util.ArrayList

(25724)

26 commonly used methods/fields.
3. java.io.IOException

(24774)

11 commonly used methods/fields.
4. java.util.Map

(21315)

24 commonly used methods/fields.
5. java.util.HashMap

(20763)

19 commonly used methods/fields.
6. java.io.File

(18464)

50 commonly used methods/fields.
7. java.util.Arrays

(16678)

17 commonly used methods/fields.
8. java.io.InputStream

(16417)

9 commonly used methods/fields.
9. java.util.Set

(15421)

17 commonly used methods/fields.
10. java.util.Collections

(15143)

49 commonly used methods/fields.
11. java.util.Iterator

(14511)

4 commonly used methods/fields.
12. java.util.Date

(13229)

28 commonly used methods/fields.
13. java.util.HashSet

(12899)

16 commonly used methods/fields.
14. java.util.Collection

(12804)

16 commonly used methods/fields.
15. java.net.URL

(12181)

23 commonly used methods/fields.
16. org.junit.Test

(11940)

2 commonly used methods/fields.
17. java.io.BufferedReader

(11331)

8 commonly used methods/fields.
18. java.io.FileInputStream

(11300)

6 commonly used methods/fields.
19. java.io.InputStreamReader

(11241)

4 commonly used methods/fields.
20. java.io.FileOutputStream

(10667)

5 commonly used methods/fields.
21. java.io.OutputStream

(10127)

6 commonly used methods/fields.
22. android.os.Bundle

(10003)

72 commonly used methods/fields.
23. java.io.FileNotFoundException

(9968)

5 commonly used methods/fields.
24. java.util.regex.Pattern

(9858)

16 commonly used methods/fields.
25. android.content.Context

(9442)

72 commonly used methods/fields.
26. java.io.Serializable

(9356)

3 commonly used methods/fields.
27. java.text.SimpleDateFormat

(9242)

19 commonly used methods/fields.
28. java.util.LinkedList

(9206)

35 commonly used methods/fields.
29. android.view.View

(9080)

292 commonly used methods/fields.
30. java.lang.reflect.Method

(8976)

30 commonly used methods/fields.
31. java.io.ByteArrayOutputStream

(8957)

8 commonly used methods/fields.
32. java.util.Locale

(8563)

41 commonly used methods/fields.
33. java.util.Random

(8485)

8 commonly used methods/fields.
34. android.app.Activity

(8440)

84 commonly used methods/fields.
35. java.util.Comparator

(8384)

6 commonly used methods/fields.
36. java.io.UnsupportedEncodingException

(8166)

5 commonly used methods/fields.
37. android.util.Log

(8033)

16 commonly used methods/fields.
38. java.util.regex.Matcher

(7792)

19 commonly used methods/fields.
39. android.content.Intent

(7776)

187 commonly used methods/fields.
40. java.util.Properties

(7768)

28 commonly used methods/fields.
41. android.widget.TextView

(7663)

124 commonly used methods/fields.
42. org.junit.Before

(7515)

0 commonly used methods/fields.
43. java.io.ByteArrayInputStream

(7451)

7 commonly used methods/fields.
44. java.util.concurrent.TimeUnit

(6929)

20 commonly used methods/fields.
45. java.util.Calendar

(6909)

72 commonly used methods/fields.
46. java.util.Map.Entry

(6896)

4 commonly used methods/fields.
47. java.net.MalformedURLException

(6889)

5 commonly used methods/fields.
48. java.lang.reflect.InvocationTargetException

(6886)

4 commonly used methods/fields.
49. java.io.PrintWriter

(6804)

10 commonly used methods/fields.
50. java.lang.reflect.Field

(6792)

34 commonly used methods/fields.
51. android.view.ViewGroup

(6724)

70 commonly used methods/fields.
52. java.net.URI

(6135)

29 commonly used methods/fields.
53. android.view.LayoutInflater

(6076)

9 commonly used methods/fields.
54. android.widget.Toast

(6013)

10 commonly used methods/fields.
55. java.util.LinkedHashMap

(5963)

14 commonly used methods/fields.
56. java.util.Enumeration

(5944)

2 commonly used methods/fields.
57. java.io.StringWriter

(5798)

6 commonly used methods/fields.
58. android.view.Menu

(5726)

18 commonly used methods/fields.
59. android.view.MenuItem

(5544)

36 commonly used methods/fields.
60. java.io.FileReader

(5512)

2 commonly used methods/fields.
61. org.slf4j.Logger

(5431)

11 commonly used methods/fields.
62. org.slf4j.LoggerFactory

(5408)

2 commonly used methods/fields.
63. java.io.FileWriter

(5388)

4 commonly used methods/fields.
64. java.util.logging.Logger

(5322)

27 commonly used methods/fields.
65. android.net.Uri

(5315)

36 commonly used methods/fields.
66. java.text.ParseException

(5288)

7 commonly used methods/fields.
67. android.util.AttributeSet

(5258)

11 commonly used methods/fields.
68. java.util.concurrent.Executors

(5251)

8 commonly used methods/fields.
69. android.os.Handler

(5194)

16 commonly used methods/fields.
70. java.util.UUID

(5188)

10 commonly used methods/fields.
71. java.io.Reader

(5167)

9 commonly used methods/fields.
72. android.widget.ImageView

(5152)

84 commonly used methods/fields.
73. android.widget.Button

(5109)

40 commonly used methods/fields.
74. java.io.BufferedInputStream

(5099)

7 commonly used methods/fields.
75. java.security.NoSuchAlgorithmException

(5097)

5 commonly used methods/fields.
76. java.net.URISyntaxException

(5046)

6 commonly used methods/fields.
77. java.nio.charset.Charset

(4948)

14 commonly used methods/fields.
78. java.io.Writer

(4920)

6 commonly used methods/fields.
79. java.lang.annotation.Retention

(4889)

1 commonly used methods/fields.
80. java.text.DateFormat

(4808)

20 commonly used methods/fields.
81. java.io.OutputStreamWriter

(4804)

5 commonly used methods/fields.
82. java.util.TreeMap

(4773)

26 commonly used methods/fields.
83. java.lang.reflect.Constructor

(4733)

18 commonly used methods/fields.
84. android.widget.ListView

(4728)

96 commonly used methods/fields.
85. android.content.SharedPreferences

(4726)

14 commonly used methods/fields.
86. android.graphics.Bitmap

(4702)

31 commonly used methods/fields.
87. android.os.Build

(4672)

13 commonly used methods/fields.
88. java.util.concurrent.ConcurrentHashMap

(4589)

13 commonly used methods/fields.
89. java.io.BufferedWriter

(4580)

5 commonly used methods/fields.
90. java.nio.ByteBuffer

(4560)

47 commonly used methods/fields.
91. java.util.TreeSet

(4543)

26 commonly used methods/fields.
92. java.util.logging.Level

(4528)

13 commonly used methods/fields.
93. org.junit.runner.RunWith

(4515)

1 commonly used methods/fields.
94. java.io.StringReader

(4509)

3 commonly used methods/fields.
95. android.content.DialogInterface

(4499)

13 commonly used methods/fields.
96. java.util.concurrent.ExecutorService

(4461)

9 commonly used methods/fields.
97. java.lang.annotation.RetentionPolicy

(4456)

3 commonly used methods/fields.
98. java.security.MessageDigest

(4444)

9 commonly used methods/fields.
99. android.widget.EditText

(4410)

58 commonly used methods/fields.
100. org.junit.After

(4405)

0 commonly used methods/fields.

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