Questions and Exercises: Java Fundamentals

1. In the Java programming language, all source code is first written in plain text files ending with the ______ extension.

1. .javac
2. .java
3. .class
4. .txt

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Answer : b

2. The Java compiler generates

1. machine code
2. source code
3. byte code
4. HTML

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Answer : c

3. JVM stands for

1. Java Variable Machine
2. Java Variable Method
3. Java Virtual Method
4. Java Virtual Machine

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Answer : d

4. Write the statement to

1. compile HelloWorldApp application
2. Run the program

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Answer : 
i. javac HelloWorldApp.java
ii. java HelloWorldApp

5. Write the signature of the main method.

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public static void main(String[] args)

6. These characters mark the beginning of a single-line comment.

1. //
2. /*
3. */
4. /**

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Answer : a

7. Which of the following are not valid assignment statements?

1. sum = 9;
2. 72 = cost;
3. price = 129;
4. ans = 'y';

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Answer : b

8. Which of the following are valid Java identifiers?

1. myFirstProgram
2. 1stProgram
3. Program1
4. David'sFirstProgram
5. First Program
6. FIRST_PROGRAM

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Answer : a, c, f

9. This is a named storage location in the computer's memory.

1. class
2. keyword
3. variable
4. operator

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Answer : c

10.This keyword is used to declare a named constant.

1. constant
2. namedConstant
3. final
4. concrete

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Answer : c

11. Which of the following is not primitive data type?

1. String
2. double
3. boolean
4. int

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Answer : a

12. Write Java statements that accomplish the following.

1. Declare int variables a and b.
2. Initialize an int variable x to 10 and a char variable ch to 'y'.
3. Declare and initialize a double variable payRate to 12.50.
4. Declare a boolean variable ans and set the value of ans to true.

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Answer : 

i. int a, b;
ii. int x = 10; char ch = 'y';
iii. double payRate = 12.50;
iv. boolean ans = true;

13. Write the output of the following expressions.

1. System.out.println(13 / 4);
2. System.out.println(2 + 12 / 4);
3. System.out.println(21 % 5);
4. System.out.println(3 - 5 % 7);
5. System.out.println(17.0 / 4);
6. System.out.println(8 - 5 * 2.0);
7. System.out.println(14 + 5 % 2 - 3);
8. System.out.println(15.0 + 3 / 2);

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Answer :

i. 3
ii. 5
iii. 1
iv. -2
v. 4.25
vi. -2.0
vii. 12
viii. 16.0

14. What is the value of each variable after the last statement executes?

int a, b, c;
double x, y;
a = 17;
b = 15;
a = a + b / 4;
c = a % 3 + 4;
x = 17 / 3 + 6.5;
y = a / 4.0 + 15 % 4 - 3.5;

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Answer :

a = 20
b = 15
c = 6
x = 11.5
y = 4.5

15. Suppose x, y, and sum are int variables and z is a double variable. What value is assigned to sum variable after statement executes? Suppose x = 3, y = 5, and z = 14.1.

sum = x + y + (int) z;

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Answer :
22

16. Write equivalent statements using combined assignment for the following, if possible.

1. x = 2 * x;
2. x = x + y - 2;
3. sum = sum + num;
4. y = y / (x + 5);

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Answer :

i. x *= 2;
ii. x += y - 2;
iii. sum += num;
iv. y /= (x+5)

17. Change the SampleProgram.java program so that it displays Programming is fun! instead of Hello World!.

class SampleProgram
{
    public static void main(String[] args)
    {
        System.out.println("Hello World!");
    }
}

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class SampleProgram
{
    public static void main(String[] args)
    {
        System.out.println("Programming is fun!");
    }
}

18. The FixProgram.java has some errors. Fix the errors so that the program successfully compiles and runs.

class FixProgram
{
    public static void main(String[] args)
    {
        System.out.println('Hello World!')
    }
}

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class FixProgram
{
    public static void main(String[] args)
    {
        System.out.println("Hello World!"); 
    }
}