Java Question Tags for Class 8

Syntax Questions

1. Give the syntax of the if statement with an example.
   Syntax:

   if(<condition>){
       <statement(s)>
   }

   Example:

   if(marks >= 40)
       System.out.println("Pass");

2. Write the syntax/general format of for statement. Give an example.
   Syntax:

   for(<initialization>; <boolean expression>; <increment/decrement>){
       <statement(s)>
   }

   Example:

   for(i = 1; i <= 10; i++)
       System.out.println(i);

Counters and Accumulators

1. Given the three Java statements, state which one among them is a counter and which one an accumulator:
   a. i++; (counter)
   b. a = a + 5; (accumulator)
   c. a += 5; (accumulator)

Output-based Questions

1. Write the output of the following code in Java:
   int a = 8, b = 18;
System.out.println("a = " + a + "\tb = " + b);
System.out.println("Sum + " + (a + b));
System.out.println("Difference = " + (b - a));
   OUTPUT:

   a = 8        b = 18
   Sum + 26
   Difference = 10

2. Find the output:
   int x = 4, y = 81;
System.out.println(x > y);
System.out.println(Math.sqrt(y));
System.out.println(++x + (y % x));
   OUTPUT:
   false
9.0
6
3. If a = 24 and b = 12, then find and display the values of a, b, and c in the following expression:
   c = a++ - --b;
   a = 25.
   b = 11.
   c = 24 – 11 = 13.
4. Find the output of the given code:
   int a = 5, b = 2, c = 8;
b += ++a - b;
c -= a++ + ++b;
System.out.print("a = " + a + "\nb = " + b + "\nc = " + c);
   b = b + ++a – b
   ⇒b = 2 + 6 – 2 = 6
   c = c – (a++ + ++b)
   ⇒c = 8 – (6 + 7) = -5
   OUTPUT:
   a = 7
   b = 7
   c = -5
5. Find the output for the following code:
   int a = 5, b = 3;
b += ++a + a++;
System.out.print("a = " + a + "\nb = " + b);
   OUTPUT:
   a = 7
b = 15

Theory Questions:

1. Differentiate between if and if-else with example.
   The if statement contains statements only for the true block.

   if(marks >= 40)
       System.out.println("Pass");

   The if-else statement contains statements both for true and false block.

   if(marks>= 40)
       System.out.println("Pass");
   else
       System.out.println("Fail");

2. What are Java Tokens? Name three of them.
   Java tokens are the basic building blocks of a Java program.
   Keywords, Identifiers and Literals are three Java tokens.
3. What is Java? When was it invented and by whom?
   Java is an object-oriented, platform-independent programming language.
   It was developed in 1991 by James Gosling, but the first version was released in the year 1995.
4. Why is Java called a platform independent language?
   When a Java program is compiled, it produces bytecode, which is platform independent because it can execute in any platform, having JVM. Thus, Java is called a platform independent language.
5. What is the difference between variable and keyword?
   Variables are also known as identifiers in Java. They are the named storage locations that hold values.
   Example:
   int x = 5; //x is a variable
   Keywords are special words in Java that have a special meaning to the compiler.
   Example:
   public, static, void.
6. Differentiate between = and == in Java.
   The = sign is an assignment operator. It is used to assign a value to a variable.
   Example:
   int x = 5;
   The == sign is a relational operator. It is used to compare two values for equality.
   Example:

    

   if(x == y)
       System.out.println("Same");

7. State the difference between System.out.print() and System.out.println() with an example for each.
   The print() method displays the message and keeps the cursor on the same line.
   Example:
   System.out.print("Hello ");
System.out.print("World");
   OUTPUT:
   Hello World
   The println() method displays the message and takes the cursor to the next line.
   Example:
   System.out.println("Hello ");
System.out.println("World");
   OUTPUT:
   Hello
World
8. Differentiate between prefix and postfix.
   In prefix, the variable first updates its value, and then assigns it.
   Example:
   int x = 5;
int y = ++x; //y gets 6
   Whereas in postfix, the variable first assigns its value, then later it updates it.
   Example:
   int x = 5;
int y = x++; //y gets 5
9. Differentiate between a counter and an accumulator.
   A counter is a variable that increments/decrements its value by 1 each time. They are mainly used to count a certain operation that repeats in a program.
   Example:
   x++;
   An accumulator is a variable that updates its value, but not by 1. They are mainly used to find the result of a calculation that involves many values, like the total sum, factorial, etc.
   Example:
   x += 5;
10. State the function of Math.pow() and Math.sqrt(), with an example each.
    Math.pow() function returns the value of the first argument raised to the power of the second argument.
    Example:
    double p = Math.pow(2, 3); //p gets 8.0
Math.sqrt() function returns the square root of a positive number.
    Example:
    double s = Math.sqrt(49); //s gets 7.0
11. State any three rules for naming a variable in Java.
    Following are the three rules for naming variables in Java:
    a. Variable names can begin with a letter, underscore or dollar sign.
    b. Variables can’t be the same as the keywords.
    c. Variables are case-sensitive.
12. Write the symbols and names of the logical operators. What is their order of precedence?
    The three logical operators are Logical AND (&&), Logical OR (||) and Logical NOT (!). The order of precedence is NOT –> AND –> OR.

Conditional Operators

1. Rewrite without using if:

   if(bill < 7000)
       discount = 0.05;
   else
       discount = 0.1;

   discount = (bill < 7000)? 0.05 : 0.1;

2. Give the syntax of the ternary operator and also an example.
   Syntax:
   <variable> = (<boolean expression>)? <value 1> : <value 2>;
   Example:
   int max = (a > b)? a : b;
3. Rewrite the given code without using ternary operator:
   double ans = (value > 10000)? 0.05 * value : 0.02 * value;

   double ans;
   if(value > 10000)
       ans = 0.05 * value;
   else
       ans = 0.02 * value;

Debug the Errors

1. Find and correct the errors (if any):

   Circle class
   {
       public static voidmain(string args[])
       {
           double a = 75.57d, 12.56d, 11.73d, smo = 0.0d
           a + b + c = sum;
           System.out.println("Sum of numbers = " + sum);
       }
   }

   Correct Code:

   class Circle
   {
       public static void main(String args[])
       {
           double a = 75.57d, b = 12.56d, c = 11.73d, sum = 0.0d;
           sum = a + b + c;
           System.out.println("Sum of numbers = " + sum);
       }
   }

Java Expressions:

1. Write the following expression in one Java statement:
   t = 3 / 7 (a⁷ + d⁴)
   t = 3.0 / 7 * (Math.pow(a, 7) + Math.pow(d, 4));