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Java / Design Patterns

In Java singleton, how do you prevent creating instance using reflection?

Create a constructor and throw InstantiationError when the private singleton instance reference is not null.

private Singleton() {
    if( Singleton.singleton != null ) {
        throw new InstantiationError( "Creating of this object is not allowed." );
    }
}

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OOPS Concepts and its implementation in Java 18 Inheritance 29 Java Identifiers 4 JDK, JRE, JVM, JIT 69 Object, Class and Package 44 Variable 9 Class Variables (Static Variables) 13 Instance Variables (Non Static Variables) 3 Local Variables 6 Operators 9 Package 10 Data types 10 Modifiers 29 Methods 38 Control Statements 12 Access Modifiers 5 Constructor 38 Interface 46 Abstract Class 19 Enum 20 Arrays 11 Strings 32 Using String 29 Exception 55 Collections 56 List and its implementations 22 Map and its implementations 36 Set and its implementations 23 Queue and its implementations 4 Regular expressions 3 Design Patterns 75 Generics 20 Casting 5 volatile 13 Java ThreadLocal 10 Java Multithreading 113 Java Multithreading part II 17 final keyword 13 static keyword 16 Concurrent collections 55 Java Serialization 36 JDBC 53 JNDI 17 RMI 6 JAXB 10 JMX 9 log4j 18 Annotations 10 XML 14 Garbage collection 31 Programs 8 JVM 4 Java8 streams 25 JavaFX 6 Autosys 9

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