How to input a sentence in Java

you can use scan.nextLine(); to read the entire line.

you can try the following, it will work.

public static void main(String args[]) {    
        // Create a new scanner object
        Scanner scan = new Scanner(System.in); 

        // Scan the integer which is in the first line of the input
        int i = scan.nextInt(); 

        // Scan the double which is on the second line
        double d = scan.nextDouble(); 

        /* 
         * At this point, the scanner is still on the second line at the end
         * of the double, so we need to move the scanner to the next line
         * scans to the end of the previous line which contains the double. 
         */
        scan.nextLine();    

        // reads the complete next line which contains the string sentence            
        String s = scan.nextLine();    

        System.out.println("String: " + s);
        System.out.println("Double: " + d);
        System.out.println("Int: " + i);
  }

You should put a scan.nextLine() after the above integer scan and the double scan. Then use String s = scan.nextLine(). Like this,

int i = scan.nextInt();
scan.nextLine();
double d = scan.nextDouble();
scan.nextLine();
String s = scan.nextLine();