Java String – String methods with examples

Java String

String is sequence of characters.

String is a Java class and is under package – Java.lang.String 

 

String declaration:

• String str = “hello world 123”; //String literal

str is a String object

• String MyStr = new String(“My world is great!”); //String new object

 

Watch demo –

 

Sample String declaration –

System.out.println("str - " + str);
System.out.println("MyStr - " + MyStr);

OutPut :

str – hello world 123

MyStr – My world is great!

 

String constructor – 

char data[] = {'h', 'e', 'y'};
String CharString = new String(data); //Parameterised constructor
System.out.println(CharString);

OutPut :

hey

String methods

 

charAt –

Returns the character present exactly on specified index

String str = "hello world 123";
System.out.println(str.charAt(6));

OutPut –

w

 

substring –

String str = "hello world 123";
//returns the rest of the string from the specified index, 6th index to end of string/index
System.out.println(str.substring(6));

//returns the string from begin to end index, 6th index to a particular index/specified index
System.out.println(str.substring(6, 13));

OutPut

world 123

world 1

 

concat –

String str = "hello world 123";
char data[] = {'h', 'e', 'y'};

String CharString = new String(data);

system.out.println(str.concat("4567")); // str = str+"4567"
System.out.println(str.concat(CharString)); //str = str + CharString

OutPut

hello world 1234567

hello world 123hey

 

Some more String methods – 

public class StringExamples {
	public static void main(String[] args) {
		String str = "hello world 123";
		
		String MyStr = new String("My world is great!");
		
		char data[] = {'h', 'e', 'y'};
		String CharString = new String(data);

		System.out.println(str.indexOf("world"));
		System.out.println(CharString.indexOf('e'));
		
		System.out.println(str.contains("123"));
		System.out.println(str.contains("Hello"));
		
		//System.out.println(str.equals("1234456"));
		
		System.out.println(str.toUpperCase());
		
		String str1 = "Hello";
		String  str2 = "hello";
		System.out.println(str1.equals(str2));
		System.out.println(str1.equalsIgnoreCase(str2));
		
		String TrimeMyString = "     123ASDF    ";
		System.out.println(TrimeMyString);
		System.out.println(TrimeMyString.trim());
		
		//System.out.println(str1.replace('H', 'Y'));
		String ReplacedString = null;
		ReplacedString = str1.replace('H', 'Y');
		System.out.println(ReplacedString);
		System.out.println(ReplacedString.length());		
	}
}

OutPut –

6

1

true

false

HELLO WORLD 123

false

true

     123ASDF    

123ASDF

Yello

5