After compiling. Java, the following appears: Note:checkUser.java uses unchecked or unsafe operations.Note :Recompile with -Xlint :unchecked for details.

 

If it is shown in Chinese, it means:
Note: A.java USES unchecked or unsafe operations.
Note: For details, use -Xlint: Unchecked recompile.
JAVA5.0 generics are used, but the 5.0 generics do not do type checking. For example, ArrayList a =new ArrayList();
a.add(“hello”); There are several solutions to this warning:
1) Prefix a method with @Suppresswarnings (“unchecked”)
2) declare generic types, such as ArrayList< Object> A = new ArrayList< Object> (a);
3) Compile with 1.4 COMPATIBLE JDK, Javac-Source 1.4 test.java
4) You can also view warning messages like Javac Xlint: Unchecked test.java. This will display the detailed warning information


Read More: