How do I use the if-then-else statement?

The if-then-else control flow statement adds a secondary path to the if statement when the expression evaluates to false. When it evaluates to false the else block will be executed.

Below is the program that takes input of user test score and evaluates the score to get the corresponding grade.

package org.kodejava.example.lang;

import java.io.Console;

public class IfThenElseDemo {
    public static void main(String[] args) {
        //
        // Get an instance of system console for taking user
        // input.
        //
        Console c = System.console();

        int score = 0;
        String grade;

        System.out.print("Please enter your score: ");

        try {
            //
            // Take user score input and convert the input
            // value into number.
            //
            score = Integer.valueOf(c.readLine());
        } catch (NumberFormatException e) {
            e.printStackTrace();
        }

        if (score >= 90) {
            grade = "A";
        } else if (score >= 80) {
            grade = "B";
        } else if (score >= 60) {
            grade = "C";
        } else if (score >= 50) {
            grade = "D";
        } else {
            grade = "F";
        }

        System.out.println("Grade = " + grade);
    }
}

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When the program executed you'll need to input the test score and the program will give you the grade.

Please enter your score: 75
Grade = C