Unauthorized or insecure operations

This problem may occur when you use JDK or above when compiling Java source files with unchecked or insecure operations. (Unchecked or insecure operations are used. Use-xlint: unchecked to re-compile .) The reason is that the creation of collection classes in jdk1.5 is different from that in jdk1.4, mainly because the generic type is added in jdk1.5, that is, the data in the set can be checked. Before JDK 1.5, if no parameter type is specified, the JDK compiler reports the unchecked warning because it cannot check whether the given parameter meets the requirements, which does not affect the running. Follow the prompts to cancel the warning by specifying the parameter. You can also specify a type parameter for the parameter. List temp = new arraylist (); temp. add ("1"); temp. add ("2"); change to list <string> temp = new arraylist <string> (); temp. add ("1"); temp. add ("2 ");