Java String Coding Questions and Answers

Welcome to the Java String Coding Quiz. In this quiz, we present 10 coding MCQ questions to test your coding knowledge on the Java String topic. Each question has a correct and brief explanation.

1. What is the output of the following Java code snippet?

String str = "Hello World";
System.out.println(str.length());

a) 10

b) 11

c) 12

d) 13

Answer:

b) 11

Explanation:

The length() method returns the number of characters in the string, including spaces. "Hello World" has 11 characters.

2. What does this Java code snippet output?

String s1 = "Java";
String s2 = new String("Java");
System.out.println(s1 == s2);

a) true

b) false

c) Java

d) An error

Answer:

b) false

Explanation:

'==' compares references, not values. s1 and s2 refer to different objects, so the output is false.

3. Identify the output of the following code:

String text = "JavaProgramming";
System.out.println(text.substring(4, 7));

a) Java

b) Prog

c) gram

d) Pro

Answer:

d) Pro

Explanation:

substring(int startIndex, int endIndex) returns the string from startIndex (inclusive) to endIndex (exclusive). Here, it's "Pro".

4. What will be printed by this Java code?

String str1 = "Java";
String str2 = "Java";
System.out.println(str1.equals(str2));

a) true

b) false

c) Java

d) An error

Answer:

a) true

Explanation:

The equals() method compares the values of strings. str1 and str2 have the same value, so the result is true.

5. What does this code snippet output?

String word = "Hello";
word.concat(" World");
System.out.println(word);

a) Hello

b) World

c) Hello World

d) An error

Answer:

a) Hello

Explanation:

Strings in Java are immutable. concat() creates a new string, which is not assigned to a word. So, the word remains unchanged.

6. What is the result of executing this code?

String a = "Java";
String b = " Programming";
String c = a + b;
System.out.println(c);

a) Java

b) Programming

c) Java Programming

d) An error

Answer:

c) Java Programming

Explanation:

The + operator concatenates two strings, creating a new string "Java Programming".

7. What will the following Java code snippet output?

String str = "Java";
System.out.println(str.toUpperCase());

a) java

b) JAVA

c) Java

d) An error

Answer:

b) JAVA

Explanation:

The toUpperCase() method converts all characters in the string to upper case.

8. What does the following code snippet print?

String text = "Java";
System.out.println(text.replace('a', 'x'));

a) Jxvx

b) Javx

c) Jxva

d) Java

Answer:

a) Jxvx

Explanation:

The replace(char oldChar, char newChar) method replaces all occurrences of the specified old character with the new character.

9. Determine the output of this Java code:

String s = "programming";
System.out.println(s.charAt(3));

a) p

b) r

c) o

d) g

Answer:

d) g

Explanation:

charAt(int index) returns the char value at the specified index. Indexing starts from 0, so s.charAt(3) is 'g'.

10. What is the result of the following code snippet?

String first = "Java";
String second = "Python";
System.out.println(first.compareTo(second));

a) A positive number

b) A negative number

c) 0

d) An error

Answer:

b) A negative number

Explanation:

compareTo() compares two strings lexicographically. Since "Java" is lexicographically less than "Python", it returns a negative number.