Unit 2 Java String Concepts

What is the purpose of the String class in Java?

• The purpose of the String class in Java is to represent and manipulate sequences of characters.

• To handle file input and output in Java.

• To create user interfaces in Java.

• To store numerical values in Java.

How do you create a String object in Java?

• String str = "Hello, World!";

• String str = 'Hello, World!';

• String str = new String();

• String str = new String('Hello, World!');

What method would you use to find the length of a String?

• Count the characters manually.

• Apply the 'getLength' function.

• Use the 'size' method.

• Use the 'length' property or method.

Explain the concept of String immutability in Java.

• In Java, strings are mutable and can be altered at any time.

• String immutability in Java means that once a string is created, it cannot be altered, and any changes result in a new string object.

• Strings in Java can be modified directly after creation.

• String immutability allows changing the original string without creating a new one.

Which method would you use to convert a String to uppercase?

• Use the 'string.uppercase()' function

• Use the 'capitalize()' method

• Use the 'toLowerCase()' method

• Use the 'toUpperCase()' method (Java) or 'upper()' method (Python) to convert a String to uppercase.

How can you compare two Strings for equality in Java?

• Use str1.compareTo(str2) for equality check.

• Use str1 == str2 for content equality.

• Use str1.equals(str2) for content equality.

• Use str1.equalsIgnoreCase(str2) for exact match.

What does the method substring(int beginIndex) do?

• It returns the entire string.

• It returns a substring from the start to the specified index.

• It removes the specified index from the string.

• It returns a substring from the specified index to the end of the string.

How do you concatenate two Strings in Java?

• You can concatenate two strings using the '&' operator.

• Strings can only be concatenated using the StringBuilder class.

• You can concatenate two strings in Java using the '+' operator or the String.concat() method.

• You must use the String.join() method to concatenate strings.

What is the result of calling the method indexOf(char ch) on a String?

• The total number of characters in the string.

• The index of the first occurrence of the character, or -1 if not found.

• A boolean indicating if the character exists in the string.

• The last occurrence of the character in the string.

Can you modify a String object after it has been created? Why or why not?

• Yes, you can modify a String object directly.

• No, you cannot modify a String object after it has been created.

• String objects can be changed using methods.

• Strings are mutable and can be altered after creation.