String Functions in java

Introduction to String Functions in Java:

Number of methods provided in Java to perform operations in Strings is called String functions. The methods are compare(), concat(), equals(), split(), length(), replace(), compareTo() and so on. Strings in Java are constant and it is created either using a literal or using a keyword. String literal is used to make Java memory efficient and the keyword creates Java string in normal memory. The string represents an array of character values and the class is implemented by three interfaces such as Serializable, Comparable, and CharSequence interfaces. It represents the sequence of characters in a serialized or comparable manner.

Main Concept of string functions in Java

• Creating String: There are two ways in which a String object can be created in Java:

Using a string literal: String literal in Java can be created using double-quotes.
Example: String s= “Hello World!”;

Using the new keyword: Java String can be created by using a keyword “new”.
Example: String s=new String (“Hello World!”);

• String length: Methods which are used to get information about an object are called accessor methods in Java. One such accessor method related to strings is the length () method. This returns the number of characters in the string object.

public class Exercise {
public static void main(String args[]{
String s1="Hello";
String s2="World";
System.out.println("string length is: "+s1.length());
System.out.println("string length is: "+s2.length());
}}

• Concatenating string: This method returns a new string which is string1 with string2 combined at the end. Concat () method can be used with string literals to get this done. Strings are also commonly concatenated using + operator.

public class ExerciseNew {
public static void main(String args[]){
String s1="Hello";
s1=s1.concat("What is your good name?");
System.out.println(s1);
}}

• Creating a format string: We have printf () and format () methods that prints output with formatted numbers. There is an equivalent class method in String called format (). It returns a String object. Static format () method available in String object allows creating a formatted string which can be reused, contrary to the one-time print statement.

Methods of string functions in Java

Following are the different methods:

Examples of functions in Java

In this section, we have discussed some examples of string functions in Java.

Example #1: Check if a string is empty

public class IsEmptyExercise{
public static void main(String args[]){
String s1="";
String s2="Hello";
System.out.println(s1.isEmpty());      // true
System.out.println(s2.isEmpty());      // false
}}

Example #2: Trim whitespaces in a string

public class StringTrimExercise{
public static void main(String args[]){
String s1="  HelloWorld   ";
System.out.println(s1+"How are you doing today");        // without trim()
System.out.println(s1.trim()+"How are you doing today"); // with trim()
}}

Example #3: Convert a string to lowercase

public class StringLowerExercise{
public static void main(String args[]){
String s1="HELLO HOW Are You TODAY?”;
String s1lower=s1.toLowerCase();
System.out.println(s1lower);}
}

Example #4: Replace a part of a string

public class ReplaceExercise{
public static void main(String args[]){
String s1="hello how are you today";
String replaceString=s1.replace('h','t');
System.out.println(replaceString); }}

Example #5: Check if two strings are equal

public class EqualsExercise{
public static void main(String args[]){
String s1="Hi";
String s2="Hey";
String s3="Hello";
System.out.println(s1.equalsIgnoreCase(s2));   // returns true
System.out.println(s1.equalsIgnoreCase(s3));   // returns false
}
}

Conclusion

Apart from the above-mentioned characteristics, functions, and methods, there are other facts too with the String class. String class is a final class and that is the reason String class objects are immutable in nature. A special memory area is reserved by JVM for string classes, this area is called String constant pool.

In the String library, available with java. Lang, overriding the String references are possible but the content or literals cannot be copied. Any number which is closed in double-quotes also treated as the string.

Students should test these codes in an IDE and make the necessary modification here and there to further enhance their understanding. String manipulation is very important to know in any programming language and it is used on a daily basis by developers.

Recommended Articles

This has been a guide to String functions in Java. Here we have discussed the different methods of string functions in java with examples. You may also look at the following article to learn more –

1. Wrapper Class in Java
2. JavaScript split String
3. Data Types in Java
4. Java String Operators