Java Scanner hasNextDouble() Method

The hasNextDouble() is a method of Java Scanner class which is used to check if the next token in this scanner's input can be interpreted as a double value using the nextDouble() method. It returns true if the scanner's input can be interpreted as a double value, otherwise returns false.

Syntax

Following is the declaration of hasNextDouble() method:

Parameter

This method does not accept any parameter.

Returns

The hasNextDouble() method returns true if and only if this scanner's next token is a valid double value.

Exceptions

IllegalStateException

Compatibility Version

Java 1.5 and above

Example 1

import java.util.*;
public class ScannerHasNextDoubleExample1 {  
    public static void main(String args[]){  
    	//Initialize the scanner
    	Scanner scan = new Scanner(" 22.10 Double number is 2123324.58");
    	//Iterate through the tokens
    	while(scan.hasNext()){
    		//Print Double value
    		if(scan.hasNextDouble()){
    			System.out.println("Found Double Value: "+scan.next());
    		}
    		else{
    			System.out.println("Not Found Double Value: "+scan.next());
    		}
    	}
    	scan.close();
	}  
}

Output:

Found Double Value: 22.10
Not Found Double Value: Double
Not Found Double Value: number
Not Found Double Value: is
Found Double Value: 2123324.58

Example 2

import java.util.*;
public class ScannerHasNextDoubleExample2 {  
    public static void main(String args[]){   	
    	  String s = "Hello World! 12 + 13.0 = 15 ";
        Float f = 2.123f;
        s = s + f;
        //Create a new scanner Object
        Scanner scanner = new Scanner(s);
        //Assign locale as US to recognize Double numbers in a string
        scanner.useLocale(Locale.US);
        while (scanner.hasNext()) {          
           //Check if the scanner's next token is Double
           System.out.println("Found Double Value: " + scanner.hasNextDouble());
           //Print scanned input
           System.out.println("Scan String: " + scanner.next());
           }    
        scanner.close();
	  }  
}

Output:

Found Double Value: false
Scan String: Hello
Found Double Value: false
Scan String: World!
Found Double Value: true
Scan String: 12
Found Double Value: false
Scan String: +
Found Double Value: true
Scan String: 13.0
Found Double Value: false
Scan String: =
Found Double Value: true
Scan String: 15
Found Double Value: true
Scan String: 2.123

Example 3

import java.util.*;
public class ScannerHasNextDoubleExample3 {  
    public static void main(String args[]){   	
    	    Scanner scan = new Scanner(System.in);
    	    System.out.print("Enter some value: ");  	    
    	    if(scan.hasNextDouble())
    	    {
    	      double y  = scan.nextDouble();
    	      System.out.println("Your entered value: " +y);
    	    }   	            
    	    else if (scan.hasNext())
    	    {
    	    	System.out.println("Please Entered the Double Value.");
    	      System.out.println("You entered: " + scan.next());
    	    }
    	    scan.close();
	    }  
}

Output:

Enter some value: JavaTpoint
Please Entered the Double Value.
You entered: JavaTpoint

Enter some value: 12345.66
Your entered value: 12345.66

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