63. Given: 11. class ClassA{} 12. class ClassB extends ClassA{} 13. class ClassC extends ClassA{} and: 21. ClassA p0 = new ClassA()； 22. ClassB p1 = new ClassB()； 23. ClassC p2 = new ClassC()； 24. ClassA p3 = new ClassB()； 25. ClassA p4 = new ClassC()； Which three are valid? (Choose three.) (A) p0 = p1； (B) p1 = p2, (C) p2 = p4； (D) p2 = (ClassC)p1； (E) p1 = (ClassB)p3； (F) p2 = (ClassC)p4；

78. A developer is creating a class Book, that needs to access class Paper. The Paper class is deployed in a JAR named myLib.jar. Which three, taken independently, will allow the developer to use the Paper class while compiling the Book class? (Choose Three.) (A) The JAR file is located at $JAVA_HOME/jre/classes/myLib.jar. (B) The JAR file is located at $JAVA_HOME/jre/lib/ext/myLib.jar. (C) The JAR file is located at /foo/myLib.jar and a classpath environment variable is set that includes /foo/myLib.jar/Paper.class. (D) The JAR file is located at /foo/myLib.jar and a classpath environment variable is set that includes /foo/myLib.jar. (E) The JAR file is located at /foo/myLib.jar and the Book class is compiled using javac -cp /foo/myLib.jar/Paper Book.java (F) The JAR file is located at /foo/myLib.jar and the Book class is compiled using javac -d /foo/myLib.jar Book.java (G) The JAR file is located at foo/myLib.jar and the Book class is compiled using javac -classpath /foo/myLib.jar Book.java

其他申論題