String Constant Pool is possible only because String is immutable in Java and its implementation of the String interning concept. The string pool is also an example of a Flyweight design pattern.
String Pool Examples String s1 = "Hello"; String s2 = "Hello"; String s3 = "Hel" + "lo"; String s4 = "Hel" + new String("lo"); String s5 = new String("Hello"); String s6 = s5.intern(); System.out.println(s1 == s2); // true System.