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Matching with a regex literal.

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If you need to match characters that are a part of the regular expression syntax you can mark all or part of the pattern as a regex literal.

\Q marks the beginning of the regex literal. \E marks the end of the regex literal. 

// the following throws a PatternSyntaxException because of the un-closed bracket
"[123".matches("[123");

// wrapping the bracket in \Q and \E allows the pattern to match as you would expect.
"[123".matches("\\Q[\\E123"); // returns true

An easier way of doing it without having to remember the \Q and \E escape sequences is to use Pattern.quote() 

"[123".matches(Pattern.quote("[") + "123"); // returns true
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Regular Expressions:
* Regular Expressions
* Using capture groups
* Using regex with custom behaviour by compiling the Pattern with flags
* Escape Characters
* Not matching a given string
* Matching with a regex literal.
* Matching a backslash
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0 Inheritance
1 Getting started with Java
2 Streams
3 Exceptions
4 Collections
5 Lambda Expressions
6 Generics
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13 Default Methods
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15 Basic Control structures
16 Concurrent Programming Threads
17 Console I/O
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19 Visibility controlling access to members of a class
20 Regular Expressions
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84 The Classpath
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91 Performance Tuning
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103 Just in Time JIT compiler
104 FTP File Transfer Protocol
105 Java Native Access JNI
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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
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129 sun.misc.Unsafe
130 Java Memory Model
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137 Java Virtual Machine JVM
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142 Java SE 8 Features
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145 Concurrency and Money
146 Concurrent Collections
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
153 JShell
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161 Using other scripting languages in Java
162 Functional interfaces
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176 Enum starting with a number
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180 StringBuffer
181 Choosing Collections
182 C++ Comparison
183 CompletableFuture
184 Contributors