String methods – isEmpty() and lastIndexof

In this post, we will discuss about 2 methods which are isEmpty and lastIndexOf.

Let’s understand them with examples.

boolean isEmpty():

Returns true , if length of the string is 0.

public class StringMethodsEx {

	public static void main(String[] args)   {
		
		String val1 = "TESTINGPOOL.COM";  
		System.out.println(val1.isEmpty()); // return false
		System.out.println(("").isEmpty());  // returns true

	}
}

lastIndexOf():

This method finds out the index of last occurrence of a char/sub-string in a particular String.

It has 4 types of implementations.

int lastIndexOf(int ch): It returns the last occurrence of character ch in the particular String.

int lastIndexOf(int ch, int fromIndex): It returns the last occurrence of ch, starting searching backward from the specified index “fromIndex”.

int lastIndexOf(String str): Returns the last occurrence of str in a String.

int lastIndexOf(String str, int fromIndex): Returns the last occurrence of str, starting searching backward from the specified index “fromIndex”.

public class StringMethodsEx {

	public static void main(String[] args)   {
		
		String val1 = "TESTINGPOOL.COM";  

		System.out.println("Last occurence of string COM :"+val1.lastIndexOf("COM")); //last occurrence of string
		System.out.println("Last occurence of char C :"+val1.lastIndexOf("C"));  // last occurrence of char
		System.out.println("Last occurence of char G, index start from 10 :"+val1.lastIndexOf("G", 10)); //lastIndexOf(int ch, int fromIndex)
		System.out.println("Last occurence of string Pool,index starts from 10 :"+val1.lastIndexOf("POOL", 10));  //lastIndexOf(String str, int fromIndex)

	}
}