Which of the following is NOT a primitive data type in Java?
Answer: C
String is a non-primitive (reference) data type in Java. Primitive types include int, boolean, double, float, char, long, short, byte.
Q.2Medium
What is the size of 'char' data type in Java?
Answer: B
The 'char' data type in Java is 2 bytes (16 bits) because it uses Unicode character encoding.
Q.3Medium
Which of the following will compile without error? public static void main(String args[]) { int x = 10; final int y = 20; y = 30; }
Answer: B
Once a final variable is assigned, it cannot be reassigned. The line 'y = 30;' will cause a compilation error.
Q.4Medium
What is the output of: System.out.println(310);
Answer: B
When both operands are integers, the division result is an integer. 310 = 3 (integer division, not floating-point).
Q.5Medium
Which operator has the highest precedence in Java?
Answer: C
Parentheses () and array access [] have the highest precedence in Java. Multiplication, division, and modulo come next, followed by addition and subtraction.
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Q.6Medium
What is the output of: System.out.println(5 > 3 ? 'A' : 'B');
Answer: A
The ternary operator (?:) evaluates the condition (5 > 3, which is true) and returns the first value 'A'.
Q.7Medium
Which statement is correct about Java variables?
Answer: A
Java variable names are case-sensitive. 'age' and 'Age' are different variables. Names cannot start with digits, cannot contain spaces, and special characters are not allowed.
Q.8Medium
Identify the output: System.out.println("Java".length());
Answer: A
The length() method returns the number of characters in the string "Java", which is 4 characters.
Q.9Medium
Which of the following is the correct way to declare and initialize an array in Java?
Answer: B
The correct syntax is 'datatype[] arrayName = {elements};' or 'datatype[] arrayName = new datatype[size];'
Q.10Medium
What will be the output: System.out.println('A' + 'B');
Answer: B
Characters are treated as their ASCII values in arithmetic operations. 'A' (65) + 'B' (66) = 131.
Q.11Medium
What is the output of: int x = 5; System.out.println(++x + x++);
Answer: B
++x increments x to 6 and uses it, then x++ uses 6 and increments to 7. So 6 + 6 = 12.
Q.12Medium
Which of the following correctly represents a long literal in Java?
Answer: D
Both 'L' and 'l' suffixes are valid for long literals in Java, though 'L' is preferred as it's less confusing with '1'.
Q.13Medium
What is the result of: System.out.println(true && false || true);
Answer: A
&& has higher precedence than ||. So: (true && false) || true = false || true = true.
Q.14Medium
Which of the following statements will compile successfully?
Answer: D
Option A fails (300 exceeds byte range). Option B works with explicit casting. Option C works (char to int conversion is implicit).
Q.15Medium
What is the output of: System.out.println(10 * 52 * 2);
Answer: A
Operators *, / have same precedence and are evaluated left to right: ((10 * 2) / 5) * 2 = (520) * 2 = 4 * 2 = 8.
Q.16Medium
What is the output of: System.out.println("5" + 3 + 2);
Answer: B
String concatenation: "5" + 3 becomes "53", then "53" + 2 becomes "532". Once a String is involved, + performs concatenation.
Q.17Medium
Which of the following correctly initializes a 2D array in Java?
Answer: C
Both syntaxes are valid in Java for declaring 2D arrays. The brackets can be placed after the type or variable name.
Q.18Medium
What will be the output: int a = 10; int b = 20; System.out.println(a > b ? "A" : "B");
Answer: B
Ternary operator: condition ? trueValue : falseValue. Since 10 > 20 is false, "B" is printed.
Q.19Medium
What is the output of: double d = 5.7; int i = (int) d; System.out.println(i);
Answer: C
Explicit casting from double to int truncates the decimal part. 5.7 becomes 5 (not rounded).
Q.20Medium
Which statement about Java's 'this' keyword is correct?
Answer: B
'this' is a reference to the current object instance. It's used to distinguish instance variables from parameters and to call other constructors.
