In this Java String tutorial, we will learn how to create a String, how to accept String input in Java, useful String methods and many more about String with examples.
What is a String?
In the computer programming world, text values are known as a String. So we can say String is a sequence of characters. A string is a class in Java and text values are stored as an object of String class.
How to Create a String Object?
In Java, there are many different ways to create a String.
//create and assign as string in a variable.
String msg="Learn to Code";
//by creating String object.
String msg=new String("Learn to Code");
//using characters array
char ch[] = {'J','a','v','a'};
String str=new String(ch);
Accept String Input in Java.
import java.util.*;
class Example
{
public static void main(String arg[])
{
String msg;
//create Scanner object
Scanner obj=new Scanner(System.in);
System.out.println("Enter Your Message");
//read String input
msg=obj.nextLine();
System.out.println(msg);
}
}
String Methods in Java.
- length() – The length() method of String class returns the length of the given string.
- equals() – The equals() method compare two Strings and returns true if and only if both String objects are the same (Small and Capital letters are not the same).
- equalsIgnoreCase() – String equalsIgnoreCase() method compares two and returns true if both the strings are same, it ignores case (Small and Capital letters are the same).
- charAt(int index) – The charAt(index) method of String returns the character at the given index.
- substring() – In Java, substring() method of String class is used to create a substring from the given string.
- concat() – String concat() method concatenates two strings and returns it.
- toLowerCase() and toUpperCase() – These methods are used to changed the case of strings.
- indexOf() – The index() method returns the index of given character. There are four different ways to use indexOf() method.
- indexOf(int ch): returns the first index of the character in the string, otherwise returns -1 if the character is not present.
- indexOf(int ch, int from): returns the index of the character after the given second parameter, from the index.
- indexOf(String str): returns the index of the substring in the String.
- indexOf(String str, int from): returns the index of the substring after the given from index.
Example: String Method example in Java.
class Example
{
public static void main(String arg[])
{
String msg="Hello World of Java";
int len=msg.length();
System.out.println(len);
//print length of string
String str="Coder Mantra";
char ch = str.charAt(2);
System.out.println(ch);
//return character d at index 2
String w = "Java Example";
String e1 = w.substring(5);
System.out.println(e1);
//Example
String e2 = w.substring(5, 8);
System.out.println(e2);
//Exa
String s = "Java".concat("Example");
System.out.println(s);
//It will print JavaExample
}
}