It is better to use their new unsynchronized replacements:

• ArrayList or LinkedList instead of Vector
• Deque instead of Stack
• HashMap instead of Hashtable
• StringBuilder instead of StringBuffer

Noncompliant Code Example

Vector cats = new Vector();

Compliant Solution

ArrayList cats = new ArrayList();

Exceptions

Use of those synchronized classes is ignored in the signatures of overriding methods.

@Override

public Vector getCats() {...}