In this HackerRank Java Singleton Pattern problem in the java programming language you need to Complete the Singleton class in your editor which contains the following components:
- A private Singleton non-parameterized constructor.
- A public String instance variable named str.
- Write a static method named getSingleInstance that returns the single instance of the Singleton class.
HackerRank Java Singleton Pattern problem solution.
import java.io.*; import java.util.*; import java.text.*; import java.math.*; import java.util.regex.*; import java.lang.reflect.*; class Singleton{ static Singleton instance = new Singleton(); private Singleton() { } public String str; static Singleton getSingleInstance() { return instance; } }
Second solution
import java.io.*; import java.util.*; import java.text.*; import java.math.*; import java.util.regex.*; import java.lang.reflect.*; class Singleton{ public String str; private static Singleton instance; private Singleton() { } public static Singleton getSingleInstance () { if (instance == null) { instance = new Singleton(); } return instance; } }
The third solution in java 8 programming.
import java.io.*; import java.util.*; import java.text.*; import java.math.*; import java.util.regex.*; import java.lang.reflect.*; class Singleton{ private volatile static Singleton instance; public static String str; private Singleton() {} static Singleton getSingleInstance() { if (instance == null) { synchronized (Singleton.class) { if (instance == null) { instance = new Singleton(); } } } return instance; } }