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Selection Statements





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Java’s Selection Statements:

Java supports two selection statements: if and switch.

These statements allow you to control the flow of your program’s execution based upon conditions known only during run time.

We discus these topics in detail in next two topics.

Before going further let us know something about Scanner class of java.

Scanner :

Let us start with one simple program for Scanner class.

import java.util.Scanner;
public class ScannerDemo 
{
	public static void main(String[] args) 
	{
		Scanner s = new Scanner(System.in);	// Here we initialize object s for Scanner class.	
		System.out.print("Enter the first value a : ");
		int a = s.nextInt();	// Scan int type value
		System.out.print("Enter the second value b : ");
		int b = s.nextInt();	// Scan int type value
		int sum = a + b;
		System.out.println("The addition of a and b : a + b = "+sum);
	}
}

Output :

Enter the first value a : 5

Enter the second value b : 6

The addition of a and b : a + b = 11


Here we import java.uti.Scanner because the Scanner class is inside util package of java library.

Than we create reference (object) of class Scanner named s.

"System.in" This is the predefined library which allow user to enter value in any variable at run time through keyboard. We can say same as scanf() in c and cin >> in c++.

Now in Scanner class there are so many different different methods for scanning different type of values.

For Ex. in our program we use nextInt() method for scanning int type value.

Here are some in-built methods of  Scanner class for scanning different types of values.

1. nextByte()  for scanning byte type value.

2. nextShort()  for scanning short type value.

3. nextInt() for scanning int type value.

4. nextLong() for scanning long type value.

5. nextFloat() for scanning floting point value.

6. nextDouble() for scanning double type value.

7. next() for scanning a string.