分享一套JAVA英文笔试题(一)
1.What is the output of the following code?
?
public class TestEquals{ public static void main(String[] args){ String str1 = "test"; String str2 = new String("test"); String str3 = "test"; System.out.println(str1 == str2); System.out.println(str1 == str3); System.out.println(str1.equals(str2)); System.out.println(str1.equals(str3)); }}?
?
2.Equals hash codes imply that the objects are equals.True or False?
?
3.What is the size of the character data type in bytes?
?
4.Check the following code
?
class A { public void doSomething(){}}class B extends A { private void doSomething(){}}a.Is it an example of method overloading OR method overriding?
?
b.Will the program throw compilation error,runtime error OR compile and run without any errors?
?
5.Check the following code
?
class C { private void doSomething(){}}public class D extends C { public void doSomething(){}}a.Is it an example of method overloading OR method overriding?
?
b.Will the program throw compilation error,runtime error OR compile and run without any errors?
?
6.Let us assume you only have a single?user-defind public java class,the java compiler and java interpreter with you.It does not have a public static void main() method.Is it possible to execute any random code of your choice in such a java class?
?
For this question,you are NOT supposed to use any other API class or user-defined class.if you think it is possible,please write the code of the single class.if you think otherwise,please explain why it is not possible to execute code in such a class.
?
7.Can an abstract class have a "public static void main(String[] args)" method?
?
8.Check the following code
interface SuperInterface { void walk();}interface SubInterface implements SuperInterface { void run();}public class TsetInterface implements SubInterface { @Override public void walk(){ System.out.println("I am walking"); } @Override public void run(){ System.out.println("I am running"); } public static void main(String[] args) { TestInterface ti = new TestInterface(); ti.walk(); ti.run(); }}?Which of the following is correct?
a Code throws compilation error
b Code throws run-time error
c Code runs fine and output is:
I am walking
I am running
?
9.When calling the main() method of a java class,if we do not provide any arguments on the command line,then the string array of main() method-will it be empty or null?
?
10.When differentiating overloaded methods does the compiler consider the return type of the method?
?
11.Can we override an overloaded method?
?
12.Can you overload the "public static void main(String[] args)" method in java?
?
13.Can you override a static or final method in java?
?
14.Can you declare a constructor as final in java?
?
15.Is java pass-by-value Or pass-by-reference?
?
16.Can an interface implement another classes?
?
17.Which object oriented concept is achieved by using overloading and overriding?
?
18.Which class is extended by all other classes?
?
19.Can a transient variable be serialized?
?
20.Is the String class declared final?
?
21.When does the garbage collector call the finalize() method?
?
22.Write the signature of the finalize() method?
?
23.Object E has reference to object F and object F has reference to object E.There are no other references to objects E and F.Select the correct answer.
a. No objects will be garbage collected as E has reference to F and F has reference to E.
b. Only object E will be garbage collected
c. Only object F will be garbage collected
d. Both objects E and F will be garbage collected
?
24.Can we call the garbage collector from java code?if yes,how?if no,why not?
?
25.Can we force garbage collector to run?
?
26.How can you monitor garbage collection?
?
27.Can you change values of an immutable object?
?
28.List the different access specifiers
?
?