單項(xiàng)選擇題

1. class A {
2. public String toString （） {
3. return “4”；
4. }
5. }
6. class B extends A {
7. public String toString （） {
8. return super.toString（） + “3”；
9. }
10. }
11. public class Test {
12. public static void main（String[]args） {
13. System.out.printIn（new B（））；
14. }
15. }
What is the result？（）

A. Compilation succeeds and 4 is printed.
B. Compilation succeeds and 43 is printed.
C. An error on line 9 causes compilation to fail.
D. An error on line 14 causes compilation to fail.
E. Compilation succeeds but an exception is thrown at line 9.

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多項(xiàng)選擇題

Which two demonstrate encapsulation of data？（）

A. Member data have no access modifiers.
B. Member data can be modified directly.
C. The access modifier for methods is protected.
D. The access modifier to member data is private.
E. Methods provide for access and modification of data.

單項(xiàng)選擇題

public class Test {
public static void main （String [] args） {
string foo = “blue”；
string bar = foo；
foo = “green”；
System.out.printIn（bar）；
}
}
What is the result？（）

A. An exception is thrown.
B. The code will not compile.
C. The program prints “null”
D. The program prints “blue”
E. The program prints “green”

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Which two demonstrate encapsulation of data？（）

public class Test { public static void main （String [] args） { string foo = “blue”； string bar = foo； foo = “green”； System.out.printIn（bar）； } } What is the result？（）

Which two demonstrate encapsulation of data？（）

public class Test {
public static void main （String [] args） {
string foo = “blue”；
string bar = foo；
foo = “green”；
System.out.printIn（bar）；
}
}
What is the result？（）