3. Fill the blanks. (Write down the correct answers in the blanks.)(15') (1) The extension name of the Java source file is (2) When we compile a java source successfully, it will generate one or more bytecode files, and the extension name for these bytecode files are: . Assume that we have successfully compiled a java source file named: Hello.java, then we can type: to execute the program under the command-line mode. (3) List 4 primitive data types in Java are (case sensitive): and list their corresponding wrapper classes on the following lines (case sensitive): (4) All the classes in Java are inherited from the root class: ; all the classes in Java have the methods (list 3 methods' names): (5) There is a special kind of method called: programmers can use this method to initialize the class's objects and instances. (6) The access modifiers in Java are the following: public, , and default package access. The access modifier has the weakest restricted rules. (7) Usually Java can perform garbage collection automatically, but we still can the system method to invoke the Java garbage collection proactively. This method is: (8) Consider the following String codes: Code: Strings1=newString("ok");Strings2=newString("ok"); The result value of the expression: s1=s2 is : The result value of the expression: s1.equals(s2) is : (9) Can we change or modify a string value created by String class? (Yes/No). And we can also use the class to maintain the strings. (10) Several graphical packages of Java can be used to create GUI applications, please list two of Java native graphical packages or libraries