Quiz 4

Question 1

A method that is associated with an individual object is called ________.

Answer 1

A class instance.

Question 2

An object is an instance of a ________.

Answer 2

class

Question 3

Analyze the following code.

class Test {  
     public static void main(String[ ] args) { 
          String s;
          System.out.println("s is " + s);
     }
}

Answer 3

The program has a compilation error because s is not initialized, but it is referenced in the println statement.

Question 4

Analyze the following code.

public class Test {
     int x;

     public Test(String t) {
          System.out.println("Test");
     }

     public static void main(String[ ] args) {
          Test test = new Test();
          System.out.println(test.x);
     }
}

Answer 4

The program has a compile error because Test does not have a default constructor.

Question 5

Given the declaration Circle x = new Circle(), which of the following statement is most accurate?

Answer 5

x contains a reference to a Circle object.

Question 6

Given the declaration Circle[ ] x = new Circle[10], which of the following statement is most accurate?

Answer 6

x contains a reference to an array and each element in the array can hold a reference to a Circle object.

Question 7

Suppose s is a string with the value “java”. What will be assigned to x if you execute the following code?

char x = s.charAt(4);

Answer 7

Nothing will be assigned to x, because the execution causes the runtime error StringIndexOutofBoundsException.

Question 8

The keyword ________ is required to declare a class.

Answer 8

class

Question 9

What is displayed by the following code?

public static void main(String[ ] args) throws Exception {
String[ ] tokens = “Welcome to Java”.split(“o”);
for (int i = 0; i

Answer 9

Welc me t Java

Question 10

What is the output of the following code?

String s = “University”;
s.replace(“i”, “ABC”);
System.out.println(s);

Answer 10

University

Question 11

public class Test {  
     public static void main(String[ ] args) {
          String s1 = "Welcome to Java!";
          String s2 = "Welcome to Java!";

      if (s1 == s2)
           System.out.println("s1 and s2 reference to the same String object");
      else
           System.out.println("s1 and s2 reference to different String objects");
 } }

Answer 11

s1 and s2 reference to the same String object

Question 12

What is the output of the following code?

public class Test {  
     public static void main(String[ ] args) {
          String s1 = new String("Welcome to Java!");
          String s2 = new String("Welcome to Java!");

      if (s1 == s2)
           System.out.println("s1 and s2 reference to the same String object");
      else
           System.out.println("s1 and s2 reference to different String objects");
 } }

Answer 12

s1 and s2 reference to different String objects

Question 13

What is the output of the following code?

public class Test { 
     public static void main(String[ ] args) {
          String s1 = new String("Welcome to Java!");
          String s2 = new String("Welcome to Java!");

      if (s1.equals(s2))
           System.out.println("s1 and s2 have the same contents");
      else
           System.out.println("s1 and s2 have different contents");
 } }

Answer 13

s1 and s2 have the same contents

Question 14

What is wrong in the following code?

class TempClass {
     int i;
     public void TempClass(int j) {
          int i = j; 
     }
}

public class C {
     public static void main(String[ ] args) {
          TempClass temp = new TempClass(2);
     }
}

Answer 14

The program has a compilation error because TempClass does not have a constructor with an int argument.

Question 15

When invoking a method with an object argument, ________ is passed.

Answer 15

the reference of the object

Question 16

Which of the following statements is most accurate? (Choose two.)

Answer 16

A reference variable refers to an object.

An object may contain the references of other objects.

Question 17

Which of the following statements is preferred to create a string “Welcome to Java”?

Answer 17

String s = “Welcome to Java”;

Question 18

________ is a construct that defines objects of the same type.

Answer 18

A class

Question 19

________ is invoked to create an object.

Answer 19

A constructor

Question 20

________ represents an entity in the real world that can be distinctly identified.

Answer 20

An object