Got warnings from javac -Xlint:unchecked

Question

I got 2 warnings after trying to use the -Xlint switch. How can I solve these warnings?

test:quadrantRDBTemplate mymac$ javac -Xlint:unchecked -cp mysql-connector-java-5.0.jar:iucbrf.jar *.java 
QuadrantSystemRDB.java:271: warning: [unchecked] unchecked call to put(K,V) as a member of the raw type java.util.HashMap
    argMap.put(xKey, new UniformDistribution(-1, 1));
              ^
QuadrantSystemRDB.java:272: warning: [unchecked] unchecked call to put(K,V) as a member of the raw type java.util.HashMap
    argMap.put(yKey, new UniformDistribution(-1, 1));
              ^
2 warnings

Answer 1

A raw type is a type that could have a type argument, but hasn't got on. For example Map (and HashMap) can have type parameters K and V for the types of keys and values, respectively.

So you could specify a Map<Integer,String> to indicate that the map contains Integer objects as keys and maps them to String objects.

If you use simply Map then you don't provide that information. Raw types exist mostly for backwards compatibility and there is no reason to use them in new code.

Solution: provide the appropriate types to your Map. According to your code, the V would be UniformDistribution and K would be the type of yKey and xKey.