Introduced in jdk 1.5 under the class java.util to overcome drawbacks of command line argument.
If I want to communicate with keyboard then
Scanner scan = new Scanner( System.in );
In this I had past one parameter System.in which represents keyboard.
Methods Available in java.util.Scanner class for input data through keyboard:
1) next()
2) nextLine()
3) nextInt()
4) nextByte()
5) nextShort()
6) nextBoolean()
7) nextFloat()
8) nextDouble()
9) nextLong()
ScanDemo.java
import java.util.Scanner;
class ScanDemo{
public static void main(String s[] ){
Scanner scan = new Scanner(System.in);
/* In the format of String */
System.out.println("\n Enter some string data: ");
String s1 = scan.nextLine();
System.out.println("\n s1: "+s1);
/* In the format of Int */
System.out.println("\n Enter some integer data: ");
int i=scan.nextInt();
System.out.println("\n i:"+i);
}
}
class ScanDemo{
public static void main(String s[] ){
Scanner scan = new Scanner(System.in);
/* In the format of String */
System.out.println("\n Enter some string data: ");
String s1 = scan.nextLine();
System.out.println("\n s1: "+s1);
/* In the format of Int */
System.out.println("\n Enter some integer data: ");
int i=scan.nextInt();
System.out.println("\n i:"+i);
}
}
Output:
ScanDemo.java
import java.util.Scanner;
class ScanDemo{
public static void main(String s[] ){
Scanner scan = new Scanner(System.in);
System.out.println("\n Enter Some String data: ");
String b = scan.next();
System.out.println("\n b: "+b);
System.out.println("\n Enter Some String data: ");
String a = scan.nextLine();
System.out.println("\n a: "+a);
System.out.println("\n\n Program Ends");
}
}
class ScanDemo{
public static void main(String s[] ){
Scanner scan = new Scanner(System.in);
System.out.println("\n Enter Some String data: ");
String b = scan.next();
System.out.println("\n b: "+b);
System.out.println("\n Enter Some String data: ");
String a = scan.nextLine();
System.out.println("\n a: "+a);
System.out.println("\n\n Program Ends");
}
}
Output:
In this problem is that all methods except nextLine() all passing the [enter] to the next statement so in this a is taking [enter] key.
So to overcome this problem we have to take one more nextLine() method observe below:
import java.util.Scanner;
class ScanDemo{
public static void main(String s[] ){
Scanner scan = new Scanner(System.in);
System.out.println("\n Enter Some String data: ");
String b = scan.next();
System.out.println("\n b: "+b);
scan.nextLine();
System.out.println("\n Enter Some String data: ");
String a = scan.nextLine();
System.out.println("\n a: "+a);
System.out.println("\n\n Program Ends");
}
}
class ScanDemo{
public static void main(String s[] ){
Scanner scan = new Scanner(System.in);
System.out.println("\n Enter Some String data: ");
String b = scan.next();
System.out.println("\n b: "+b);
scan.nextLine();
System.out.println("\n Enter Some String data: ");
String a = scan.nextLine();
System.out.println("\n a: "+a);
System.out.println("\n\n Program Ends");
}
}
In this the enter is read by the nextLine() method.
