Java Scanner hasNext() Method

The hasNext() is a method of Java Scanner class which returns true if this scanner has another token in its input. There are three different types of Java Scanner hasNext() method which can be differentiated depending on its parameter. These are:

Java Scanner hasNext () Method
Java Scanner hasNext (String pattern) Method
Java Scanner hasNext(Pattern pattern) Method

1.Java Scanner hasNext () Method:

It is a Scanner class method which returns true if this scanner has another token in its input. This method may block while waiting for input to scan.

2.Java Scanner hasNext (String pattern) Method:

It is a Scanner class method which returns true if the next token matches the pattern constructed from the specified string.

3.Java Scanner hasNext (Pattern pattern) Method:

It is a Scanner class method which returns true if the next complete token matches the specified pattern.

Syntax

Following are the declarations of hasNext() method:

public boolean hasNext()
public boolean hasNext(String pattern)
public boolean hasNext(Pattern pattern)

Parameter

Data Type	Parameter	Description	Required/Optional
String	pattern	It is a string specifying the pattern to scan.	Required
Pattern	pattern	It is the pattern to scan for specified string.	Required

Returns

Method	Returns
hasNext()	This method returns true if and only if this scanner has another token.
hasNext(String pattern)	This method returns true if and only if this scanner has another token matching the specified pattern.
hasNext(Pattern pattern)	This method returns true if and only if this scanner has another token matching the specified pattern.

Exceptions

IllegalStateException- This method throws exception if the innvocation is done after the scanner has been closed.

Compatibility Version

Java 1.5 and above

Example 1

import java.util.*;
public class ScannerHasNextExample1 {  
    public static void main(String args[]){   	
	      //Create Scanner object
		Scanner scan = new Scanner("Hello World!");
		//Printing the delimiter used
		System.out.println("Delimiter:" + scan.delimiter());
		//Print the Strings
		while (scan.hasNext()) {
			System.out.println(scan.next());
		}
		//Close the scanner
		scan.close();
		}  
}

Output:

Delimiter:\p{javaWhitespace}+
Hello
World!

Example 2

import java.util.*;
public class ScannerHasNextExample2 {  
    public static void main(String args[]){   	
    	   String s = "Hello, This is JavaTpoint.";
         //Create scanner Object and pass string in it
         Scanner scan = new Scanner(s);
         //Check if the scanner has a token
         System.out.println("Result: " + scan.hasNext());
         //Print the string
         System.out.println("String: " +scan.nextLine());
         //Check if the scanner has a token after printing the line
         System.out.println("Final Result: " + scan.hasNext());
         //Close the scanner
         scan.close();
	   }  
	}

Output:

Result: true
String: Hello, This is JavaTpoint.
Final Result: false

Example 3

import java.util.*;
public class ScannerHasNextExample3 {  
    public static void main(String args[]){   	
    	     //Create Scanner object
    	     Scanner scan = new Scanner("Program:Java;Python;Android");
    	     //Initialize the String pattern
    	     String pattern = "Program:.*";
    	     //Check if pattern satisfies the String content
    	     if(scan.hasNext(pattern)){
    		   System.out.println("Pattern found");
    	     }
    	     else{
    		   System.out.println("Pattern not found");
    	     }
    	     scan.close();
	     }  
}

Output:

Pattern found

Example 4

import java.util.*;
public class ScannerHasNextExample4 {  
    public static void main(String args[]){   	
    	      String str = "JavaTpoint.com 15 + 15 = 18.0";
            Scanner scanner = new Scanner(str);
            //Checking scanner's next token matches "c"
            System.out.println("Result: "+scanner.hasNext("JavaTpoint.com"));
            //Checking scanner's next token matches "="
            System.out.println("Result: "+scanner.hasNext("="));
            //Print the rest of the string
            System.out.println("Rest of String: "+scanner.nextLine());
            scanner.close();
		}  
}

Output:

Result: true
Result: false
Rest of String: JavaTpoint.com 15 + 15 = 18.0

Example 5

import java.util.*;
import java.util.regex.Pattern;
public class ScannerHasNextExample5 {  
    public static void main(String args[]){   	
    	      //Create Scanner object
    		Scanner scan = new Scanner("Names:Raju1;Pawan;Suresh");
    		//Declare the delimiter
    		scan.useDelimiter(";");
    		/*Initialize the String pattern which signifies that the String
    		token contains characters of the alphabet only*/
    		Pattern pattern = Pattern.compile("[A-Za-z]*");
    		while(scan.hasNext()){
    			//Check if the token consists of declared pattern
    			if(scan.hasNext(pattern)){
    				System.out.println(scan.next());
    			}
    			else
    				scan.next();
    			}
    			scan.close();
		}  
}

Output:

Pawan
Suresh

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