Tricky Java Programming Questions

Java Program Output

Question 1: Unicode Character

Java Code


public class A {
    public static void main(String args[]) {
        //\u000d System.out.println("hello"); 
    }
}

Output


hello

The Unicode character \u000d represents a carriage return. In some contexts, this might not be visible, but in this case, it does not cause an error and the "hello" is printed.

Question 2: Arithmetic Operators

Java Code


public class Test {
    public static void main(String args[]) {
        int i = 20 + +9 - -12 + +4 - -13 + +19;
        System.out.println(i); // Output: 77
    }
}

Question 3: String and StringBuilder Comparison

Java Code


String s1 = "Java";
String s2 = "Java";
StringBuilder sb1 = new StringBuilder();
sb1.append("Ja").append("va");
System.out.println(s1 == s2); // true
System.out.println(s1.equals(s2)); // true
System.out.println(sb1.toString() == s1); // false
System.out.println(sb1.toString().equals(s1)); // true

Question 4: try-catch-finally

Java Code


public class Demo {
    public static void main(String args[]) {
        System.out.print("a");
        try {
            System.out.print("b");
            throw new IllegalArgumentException();
        } catch (RuntimeException e) {
            System.out.print("c");
        } finally {
            System.out.print("d");
        }
        System.out.print("e"); // Output: abcd
    }
}

Question 5: Variable Initialization

Java Code


public class _C {
    private static int $;
    public static void main(String main[]) {
        String a_b; //Variable not initialized
        System.out.print($); // Output: 0
        System.out.print(a_b); // Output: null
    }
}

Question 6: ArrayList and Array Manipulation

Java Code


int[] array = {6, 9, 8};
List<Integer> list = new ArrayList<>();
list.add(array[0]);
list.add(array[2]);
list.set(1, array[1]);
list.remove(0);
System.out.println(list); // Output: [9]

Question 7: Character Array Comparison

Java Code


public class Actors {
    public static void main(String arg[]) {
        char[] ca = {0x4e, 'N', 78}; //Note: \u004e should be 'N'
        System.out.println((ca[0] == ca[1]) + " " + (ca[0] == ca[2])); // Output: true true
    }
}

Question 8: Invalid switch Statement

Java Code


public class SwitchExample {
    public static void main(String args[]) {
        int x = 80;
        switch (x) {
            case x > 70: //Invalid Case
                System.out.println("True");
                break;
            case 65 < x && x <= 70: //Invalid Case
                System.out.println("False");
                break;
            default:
                System.out.println("Default"); // Output: Default
        }
    }
}

Question 9: String Concatenation

Java Code


public class StringConcat {
    public static void main(String args[]) {
        String str = "ONE" + 1 + 2 + "TWO" + "THREE" + 3 + 4 + "FOUR" + "FIVE" + 5;
        System.out.println(str); // Output: ONE12TWOTHREE34FOURFIVE5
    }
}

Question 10: Math.min()

Java Code


import java.lang.Double;
public class Demo {
    public static void main(String args[]) {
        System.out.println(Math.min(Double.MIN_VALUE, 0.0d)); // Output: -4.9E-324
    }
}

Question 11: Long Integer Calculation

Java Code


public class LongExample {
    public static void main(String[] args) {
        long longWithL = 1000 * 60 * 60 * 24 * 365L;
        long longWithoutL = 1000 * 60 * 60 * 24 * 365;
        System.out.println(longWithL + " and " + longWithoutL); // Output: 31536000000 and 2147483647
    }
}

Question 12: Static Block and Variable Calculation

Java Code


public class Demo {
    static int x = 1111;
    static {
        x = x-- - --x;
    }
    {
        x = x++ + ++x;
    }
    public static void main(String args[]) {
        System.out.println(x); // Output: 2
    }
}