Interview Questions On Java String
Suggested Interview Questions on Java String
Interview Questions On Java String
In an interview, Java string-related questions often focus on a candidate's understanding of String manipulation, comparison, immutability, and performance. Candidates may be asked about the difference between String, StringBuilder, and StringBuffer classes, and when to use each one. They could also be questioned about common methods like equals(), compareTo(), length(), substring(), and concatenation. It's important for candidates to demonstrate knowledge of how Java handles strings behind the scenes, including concepts like String Pool, intern(), and memory management. Additionally, interviewers may inquire about how to efficiently manipulate strings, handle null values, and ensure secure coding practices when working with sensitive information.
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1 - What is a Java String?
A Java String is a sequence of characters stored in the Java String pool, which is a special memory area managed by the JVM. Strings in Java are immutable, meaning that their values cannot be changed once they are created.
2) How can you create a String object in Java?
There are several ways to create a String object in Java. You can use the String literal syntax, use the String constructor, or use the StringBuffer and StringBuilder classes to create and manipulate strings.
3) Explain the difference between String, StringBuffer, and StringBuilder classes.
String: Immutable, meaning it cannot be changed once created. StringBuffer: Mutable, meaning its value can be changed. StringBuilder: Similar to StringBuffer, but not thread safe.
4) What are some common methods used to manipulate strings in Java?
Some common methods used to manipulate strings in Java include concatenation (+ operator), length(), substring(), toUpperCase(), toLowerCase(), trim(), split(), and replace().
5) How can you compare two strings in Java?
You can compare two strings in Java using the equals() method for content comparison or the == operator for reference comparison. Note that the equals() method compares the content of the strings, while the == operator compares the memory addresses.
6) What is the significance of the String pool in Java?
The String pool in Java is a special memory area where the JVM stores unique string literals. When you create a string using a string literal, the JVM checks the String pool to see if an identical string already exists. If it does, the new string object will reference the existing string in the pool, saving memory.
7) How can you convert a String to an integer in Java?
You can convert a String to an integer in Java using the parseInt() method of the Integer class. For example, Integer.parseInt("123") will return an integer value of 123. Be cautious when using parseInt() as it can throw a NumberFormatException if the string is not a valid integer.
8) Why are strings in Java immutable?
Strings in Java are immutable to ensure their security and thread safety. Immutable objects cannot be modified after creation, making them inherently thread safe. Additionally, immutability prevents accidental changes to string values, ensuring data integrity in Java applications.
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