Essential Books

Recursion

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Introduction

Recursion occurs when a method calls itself. Such a method is called recursive. A recursive method may be more concise than an equivalent non-recursive approach. However, for deep recursion, sometimes an iterative solution can consume less of a thread’s finite stack space.

This topic includes examples of recursion in Java.

Remarks

Designing a Recursive Method

When designing a recursive method keep in mind that you need: 

if (n <= 1) {
    return 1;
}
else {
    return n * factorial(n - 1);
}

Output

In this example you compute the n-th factorial number. The first factorials are:

0! = 1

1! = 1

2! = 1 x 2 = 2

3! = 1 x 2 x 3 = 6

4! = 1 x 2 x 3 x 4 = 24

…

Java and Tail-call elimination

Current Java compilers (up to and including Java 9) do not perform tail-call elimination. This can impact the performance of recursive algorithms, and if the recursion is deep enough, it can lead to StackOverflowError crashes; see http://stackoverflow.com/documentation/java/914/recursion/15048/deep-recursion-is-problematic-in-java#t=201611080249331156811

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Recursion:
* Recursion
* The basic idea of recursion
* Deep recursion is problematic in Java
* Types of Recursion
* Computing the Nth Fibonacci Number
* Computing the Nth power of a number
* Traversing a Tree data structure with recursion
* StackOverflowError recursion to loop
* Reverse a string using Recursion
* Computing the sum of integers from 1 to N
Table Of Contents
0 Inheritance
1 Getting started with Java
2 Streams
3 Exceptions
4 Collections
5 Lambda Expressions
6 Generics
7 File I/O
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9 Interfaces
10 Maps
11 Strings
12 InputStreams and OutputStreams
13 Default Methods
14 Classes and Objects
15 Basic Control structures
16 Concurrent Programming Threads
17 Console I/O
18 Singletons
19 Visibility controlling access to members of a class
20 Regular Expressions
21 Autoboxing
22 Documenting Java Code
23 Executor, ExecutorService and Thread pools
24 Object Class Methods and Constructor
25 JAXB
26 Primitive Data Types
27 Networking
28 Optional
29 Enums
30 HttpURLConnection
31 Annotations
32 Audio
33 Data Class
34 Calendar and its Subclasses
35 Nashorn JavaScript engine
36 Java Native Interface (JNI)
37 Remote Method Invocation (RMI)
38 Iterator and Iterable
39 Operators
40 Asserting
41 Scanner
42 Properties Class
43 Preferences
44 Reflection API
45 Constructors
46 ByteBuffer
47 Serialization
48 JSON in Java
49 Random Number Generation
50 Recursion
51 Polymorphism
52 StringBuilder
53 Refernce Data Types
54 Bit Manipulation
55 Java Agents
56 Encapsulation
57 Type Conversion
58 BigInteger
59 BigDecimal
60 RSA Encryption
61 Varargs Variable Arguments
62 ThreadLocal
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66 Resources on classpath
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70 Character encoding
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89 JAX-WS
90 XML XPath Evaluation
91 Performance Tuning
92 Parallel programming with ForkJoin framework
93 Common Pitfalls
94 Non-Access Modifiers
95 Java Compiler
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97 Installing Java Standard Edition
98 Process
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100 Dates and Time using java.time
101 Fluent Interface
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103 Just in Time JIT compiler
104 FTP File Transfer Protocol
105 Java Native Access JNI
106 Modules
107 Pitfalls - exceptions
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109 ServiceLoader
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111 Object References
112 Pitfalss - performance
113 Creating Images Programmatically
114 Applets
115 NIO Networking
116 New File I/O
117 Secure objects
118 Pitfalls - threads and concurrency
119 Splitting a string into fixed length parts
120 Pitfalls - nulls and NullPointerException
121 SecurityManager
122 JNDI
123 super keyword
124 java.util.Objects class
125 Java command: java and javaw
126 Atomic types
127 Floating Point Operations
128 Converting to and from strings
129 sun.misc.Unsafe
130 Java Memory Model
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133 Queues and deques
134 Runtime commands
135 NumberFormat
136 Security and Cryptograhy
137 Java Virtual Machine JVM
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139 JavaBean
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142 Java SE 8 Features
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147 Using ThreadPoolExecutor in multi-threaded applications
148 Java Editions, versions, releases and distributions
149 Dynamic method dispatch
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152 Generating Java Code
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156 Multi-release JAR files
157 Stack-Walking API
158 TreeMap and TreeSet
159 Sockets
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161 Using other scripting languages in Java
162 Functional interfaces
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164 2D graphics
165 Reflection
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171 Immutable class
172 String Tokenizer
173 File upload to S3 / AWS
174 Readers and writers
175 Hashtable
176 Enum starting with a number
177 SortedMap
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180 StringBuffer
181 Choosing Collections
182 C++ Comparison
183 CompletableFuture
184 Contributors