Java Programming Multiple Choice Questions (MCQs) and Answers

Q91 Determine the output of this pseudocode:
TRY PRINT "Start" THROW NEW EXCEPTION "Failed" CATCH EXCEPTION PRINT "Caught" END TRY PRINT "End"

Q92 What will be the result of this pseudocode?
SET arr = [1, 2, 3]
TRY
PRINT arr[3]
CATCH EXCEPTION
PRINT "Array Error" END TRY

Q93 Identify the issue in this code snippet:
try {
int x = 5 / 0;
}
catch (Exception e) {
e.printStackTrace();
}
finally {
System.out.println("Done");
}

Q94 Spot the mistake:
try {
String s = null;
System.out.println(s.length());
}
catch (NullPointerException e) {
System.out.println("Null Error");
}

Q95 Find the error in this Java code:
try {
File file = new File("test.txt");
FileReader fr = new FileReader(file);
}
catch (FileNotFoundException e) {
System.out.println("File not found");
}

Q96 Identify the flaw in this Java code:
class CustomException extends Exception { }
try {
throw new CustomException();
}
catch (CustomException e) {
System.out.println("Custom exception caught");
}

Q97 What are generics in Java?

Q98 What is the primary advantage of using generics in Java?

Q99 Which collection type does not allow duplicate elements?

Q100 What is the difference between a HashMap and a Hashtable in Java?

Q101 In Java Collections Framework, which interface represents a mapping from unique keys to values?

Q102 What happens when a duplicate key is put into a HashMap?

Q103 What is the difference between the add() and put() methods in Java's Collection Framework?

Q104 Which of the following is true about a TreeMap in Java?

Q105 What does this Java code output?
Map<Integer, String> map = new HashMap<>();
map.put(1, "Java");
map.put(2, "Python");
System.out.println(map.size());

Q106 Analyze the output of this code snippet:
List list = new ArrayList<>();
list.add("Java");
list.add("Java");
System.out.println(list.get(1));

Q107 What will this Java code print?
Set set = new HashSet<>();
set.add(1); set.add(1);
System.out.println(set.size());

Q108 What is the result of executing this code?
Map<String, Integer> map = new TreeMap<>();
map.put("Python", 3);
map.put("Java", 1);
System.out.println(map);

Q109 Determine the output of this pseudocode:
CREATE list = ["Java", "Python", "Java"] FOR EACH element IN list PRINT element

Q110 What will be the result of this pseudocode?

CREATE map SET map["Java"] = 1 SET map["Python"] = 2 SET map["Java"] = 3 PRINT map["Java"]

Q111 Analyze this pseudocode:

CREATE set ADD "Java" TO set ADD "Python" TO set ADD "Java" TO set IF "Java" IN set PRINT "Yes" ELSE PRINT "No"

Q112 What will this pseudocode output?

CREATE map SET map[1] = "Java" SET map[2] = "Python" SET map[1] = "C++" PRINT map[1]

Q113 Identify the issue in this code snippet:
List list = new ArrayList<>(); list.get(0);

Q114 Spot the mistake:
Set set = new TreeSet<>(); set.add(null);

Q115 Find the error in this Java code:
Map<String, Integer> map = new HashMap<>();
map.put(null, 1);
map.put(null, 2);
System.out.println(map.get(null));

Q116 Identify the flaw in this Java code:
List list = new LinkedList<>(); list.add("Java"); list.add(1, "Python"); list.remove(2);

Q117 What is the String Constant Pool in Java?

Q118 How does StringBuilder differ from StringBuffer in Java?

Q119 What is the result of concatenating strings using the '+' operator in Java?

Q120 Why is it recommended to use StringBuilder or StringBuffer for string manipulation in loops?