Unit 5

1. In Java, which class is used to represent a sequence of characters?

• 1. CharArray

• 1. StringArray

• 1. String

• 1. CharSequence

1. Strings in Java are:

• 1. Mutable

• 1. Immutable

• 1. Both mutable and immutable

• 1. None of the above

1. What happens when you concatenate two strings using the "+" operator in Java?

• 1. The original strings are modified

• 1. A new string object is created with the concatenated value

• 1. The "+" operator cannot be used with strings

• 1. An exception is thrown

1. Which method is used to compare two strings for equality in Java?

• 1. compare()

• 1. equals()

• 1. isEqual()

• 1. compareTo()

1. What is the result of the following code?

String str1 = "Hello";

String str2 = "hello";

System.out.println(str1.equals(str2));

• true

• false

• The code will not compile

• An exception will be thrown

1. The method length() in the String class returns:

• 1. The number of characters in the string

• 1. The number of words in the string

• 1. The size of the string in bytes

• 1. The capacity of the string

1. Which method is used to convert all characters in a string to lowercase?

• 1. toLowerCase()

• 1. convertToLower()

• 1. changeCase()

• 1. lowerCase()

1. What does the trim() method of the String class do?

• 1. Removes leading and trailing whitespaces from the string

• 1. Truncates the string to a specified length

• 1. Converts the string to uppercase

• 1. Reverses the order of characters in the string

1. Which method is used to extract a substring from a given string based on a specified range of indexes?

• 1. slice()

• 1. extract()

• 1. subsequence()

• 1. substring()

1. Which class is used for string manipulation and is more memory-efficient when building a string incrementally?

 

• 1. String

• 1. StringBuilder

• 1. StringBuffer

• 1. StringJoiner