Pitfall - Calling new StringString is inefficient

Using new String(String) to duplicate a string is inefficient and almost always unnecessary.

• String objects are immutable, so there is no need to copy them to protect against changes.
• In some older versions of Java, String objects can share backing arrays with other String objects. In those versions, it is possible to leak memory by creating a (small) substring of a (large) string and retaining it. However, from Java 7 onwards, String backing arrays are not shared.

In the absence of any tangible benefit, calling new String(String) is simply wasteful:

• Making the copy takes CPU time.
• The copy uses more memory which increases the application’s memoru footprint and / or increases GC overheads.
• Operations like equals(Object) and hashCode() can be slower if String objects are copied.