/*
 * The purpose of this program is to demonstrate the various ways in which selection statements can be used in Java.
 * We look at the 4 basic if-else structures and the ternary operator.
 */
import java.util.Scanner;
class Selection
{
	public static void main(String [] args)
	{
		//Declare a Scanner for user input
		Scanner input = new Scanner (System.in);
		
		/* Simple if statement. This is used when we need to do something only if a certain condition is true.
		 * For example, we have to determine if someone got overall extra credit for this course. To receive overall extra credit,
		 * one has to have a score of over 100%. We check for that.
		 */
		double grade;
		System.out.print("Please enter your overall grade in the class: ");
		grade = input.nextDouble();
		
		if(grade > 100)
		{
			System.out.println("You received extra credit for the class.");
		}

		/* Simple if-else statement. This is used when we have different responses to a condition. 
		 * If the condition evaluates to be true, we execute a certain set of statements, and 
		 * if it happens to be false, we excute another set of statements.
		 * For example, here we check if the user is broke, and give advise depending on their status.
		 */
		boolean broke;
		System.out.print("Are you broke? Enter true or false. : ");
		broke = input.nextBoolean();
		
		if(broke == true)
			System.out.println("You need to budget");
		else 	System.out.println("You can buy that sweater.");

		/* Multiple if-else statements. Also called an if-else ladder. It is a series of if statements, 
		 * where only one of the many possibilities is executed.
		 * Here, we calculate the letter grade for the class based on the grade the user entered earlier.
		 */

		String letterGrade = "B";
		/* If we're assigning the value inside the if statements, the compiler regonizes that the variable could potentially 
		 * never be initialized. So, we give it a dummy value at declaration. We can also eliminate some redundant code by 
		 * having this value be a default value. Over here, we initialize letterGrade with the default value "B".
		 */
		if(grade >= 93)
			letterGrade = "A";
		else	if(grade >=90) //we don't need to test for the upper limit here. We know for sure, that grade is below 93.
				letterGrade = "A-";
			else	if(grade >=87)
					letterGrade = "B+";
		// Since we set the default to "B", any grade below 87 gets the letterGrade "B".

		System.out.println("The letter grade is "+letterGrade);

		/* Nested if statements. It is possible to write if statements inside if statements.
		 * Here, we use this method to find the largest of 3 numbers.
		 */
		System.out.println("Enter 3 numbers : ");
		double a = input.nextDouble();
		double b = input.nextDouble();
		double c = input.nextDouble();
		double greatest = 0; //set greatest to some dummy value
	
		if ( a > b )
		{
			if ( a > c )
				greatest = a;
			else	greatest = c;
		}
		else
		{
			if( b > c )
				greatest = b;
			else	greatest = c;
		}
		System.out.println("The largest number is "+greatest);
		
		/* Ternary Operator. 
		 * A ternary operator is an operator that takes 3 operands. Java has only one ternary operator - ?:
		 * This works like a simple if-else statement. For more information, please see slides 17,18 and 19 of 
		 * the Selection statements slides.
		 */

		//The if-else statement about being broke can be converted to the following line.
	
		System.out.println((broke==true) ? "You need to budget" : "You can buy that sweater.");

		//It is also possible to nest this operator. It will work as long as the true and false blocks are single expressions.
		// The largest of 3 numbers example can be turned into the following line
		
		greatest = ( a > b ) ? ( a > c ) ? a : c : ( b > c ) ? b : c;

		System.out.println("The largest number is "+greatest);
	}
}