Java was developed in the mid $1990$s$.$ Over the next decades it has evolved and grown. There are many different versions of Java.

Consult the Java API. Look up the entry for the String class. Scroll down about $1$ screen, and locate the entry titled Since: This tells you what version of Java introduced this class to the library.

When was the String class incorporated into Java?

versions JDK $1\mathrm{.}0-$ JDK $1\mathrm{.}3$

versions JDK $1\mathrm{.}4-$ JDK $1\mathrm{.}6$

versions JDK $1\mathrm{.}5-$ JDK $1\mathrm{.}9$

versions after JDK $1\mathrm{.}9$