Guide [Java] Basics Exercises With Solution

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3.Write a program called Convert for inserting a

distance in kilometers from the keyboard and convert it into miles (a mile is 1609 km).

 

 

import java.util.Scanner;
public class Convert{
    public static void main(String[]aargs){
        Scanner in=new Scanner(System.in);
        System.out.println("insert a distance in kilometers : ");
        Double kilometers=in.nextDouble();
        Double miles=kilometers*1.609;
        System.out.println(kilometers+ " kilometers is equal to " +miles+ " miles");
    }
}

 

 

 

4.Write Java program to allow the user to input his/her age. Then the program will show if the person is eligible to vote. A person who is eligible to vote must be older than or equal to 18 years old.

Enter your age: 18

You are eligible to vote.

 

 

import java.util.Scanner;
public class Vote{
    public static void main(String[]args){
Scanner in=new Scanner(System.in);
System.out.println("how old are you");
int age;
age=in.nextInt();
if (age>=18){System.out.println("You are eligible to vote.");
    }
else {System.out.println("You are not eligibe to vote.");}
    }}

 

 

 

5.Write a Java program to determine whether an input number is an even number.

 

 

package even;

import java.util.Scanner;

public class Even {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int num;
        System.out.println("enter a number :");
        num = in.nextInt();
        if ((num % 2) == 0) {
            System.out.println("It is an even number.");
        } else {
            System.out.println("It is an odd number.");
        }




    }
}

 

 

 

6.Write a Java program that determines a student’s grade.

The program will read three types of scores(quiz, mid-term, and final scores) and determine the grade based on the following rules:

-if the average score >=90% =>grade=A

-if the average score >= 70% and <90% => grade=B

-if the average score>=50% and <70% =>grade=C

-if the average score<50% =>grade=F

See the example output below:

Quiz score: 80

Mid-term score: 68

Final score: 90

Your grade is B.

 

package grade;

import java.util.Scanner;

public class Grade {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int quiz;
        int midterm;
        int finalscore;
        int average;
        System.out.println("insert quiz grade : ");
        quiz = in.nextInt();
        System.out.println("insert mid-term grade : ");
        midterm = in.nextInt();
        System.out.println("insert final grade : ");
        finalscore = in.nextInt();
        average = (quiz + midterm + finalscore) / 3;
        if (average >= 90) {
            System.out.println("grade=A");
        }
        if ((average >= 70) && (average < 90)) {
            System.out.println("grade=B");
        }
        if ((average >= 50) && (average < 70)) {
            System.out.println("grade=C");
        }
        if (average < 50) {
            System.out.println("grade=F");
        }

    }
}

 

 

 

7.Write a Java program to calculate the revenue from a sale based on the unit price and quantity of a product input by the user.

 

The discount rate is 10% for the quantity purchased between 100 and 120 units, and 15% for the quantity purchased greater than 120 units. If the quantity purchased is less than 100 units, the discount rate is 0%. See the example output as shown below:

Enter unit price: 25

 

Enter quantity: 110

 

The revenue from sale: 275.0$

 

After discount: 2475.0$(10.0%)

 

 

package revenue;

import java.util.Scanner;

public class Revenue {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int unitprice, quantity;
        double revenue, afterdiscount, discount = 0;
        System.out.println("Enter unit price:");
        unitprice = in.nextInt();
        System.out.println("Enter quantity:");
        quantity = in.nextInt();
        revenue = unitprice * quantity;
        System.out.println("The revenue from sale: " + revenue + "$");
        if ((quantity >= 100) && (quantity <= 120)) {
            discount = (revenue * 10) / 100;
        }
        if (quantity > 120) {
            discount = (revenue * 15) / 100;
        }
        if (quantity < 100) {
            discount = (revenue * 0) / 100;

        }
        afterdiscount = revenue - discount;
        System.out.println("After discount: " + afterdiscount + " $");

    }
}

 

 

 

8.Write a Java program to detect key presses.(use switch)

 

If the user pressed number keys( from 0 to 9), the program will tell the number that is pressed, otherwise, program will show "Not allowed".

 

 

package keypress;

import java.util.Scanner;

public class Keypress {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.println("press a key : ");
        char key = in.next().charAt(0);
        switch (key) {
            case '0':
                System.out.println("you pressed 0. ");
                break;
            case '1':
                System.out.println("you pressed 1. ");
                break;
            case '2':
                System.out.println("you pressed 2. ");
                break;
            case '3':
                System.out.println("you pressed 3. ");
                break;
            case '4':
                System.out.println("you pressed 4. ");
                break;
            case '5':
                System.out.println("you pressed 5. ");
                break;
            case '6':
                System.out.println("you pressed 6. ");
                break;
            case '7':
                System.out.println("you pressed 7. ");
                break;
            case '8':
                System.out.println("you pressed 8. ");
                break;
            case '9':
                System.out.println("you pressed 9. ");
                break;
            default:
                System.out.println("Not Allowed");
        }

    }
}

 

 

 

9. Write a Java program that allows the user to choose the correct answer of a question.(use switch)

 

See the example below:

What is the correct way to declare a variable to store an integer value in Java?

a. int 1x=10;

b. int x=10;

c. float x=10.0f;

d. string x="10";

Enter your choice: c

 

 

package correctanswer;

import java.util.Scanner;

public class CorrectAnswer {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.println("What is the correct way to declare a variable to store an integer value in Java?");
        System.out.println("a. int 1x=10;");
        System.out.println("b. int x=10;");
        System.out.println("c. float x=10.0f;");
        System.out.println("d. string x= \"10\";");
        System.out.print("Enter ur choice : ");
        char choice = in.next().charAt(0);
        switch (choice) {
            case 'a':
                System.out.println("wrong answer.");
                break;
            case 'b':
                System.out.println("correct answer.");
                break;
            case 'c':
                System.out.println("wrong answer.");
                break;
            case 'd':
                System.out.println("wrong answer.");
                break;
            default:
                System.out.println("your choice " + choice + " dosen't exist .");

        }
    }
}

 

 

 

10.By using do while loop, write Java program to prompt the user to choose the correct answer from a list of answer choices of a question.

 

The user can choose to continue answering the question or stop answering it. See the example below:

What is the command keyword to exit a loop in Java?

 

a. int

 

b. continue

 

c. break

 

d. exit

 

Enter your choice: b

 

Incorrect!

 

Again? press y to continue:

 

 

package exitloop2;

import java.util.Scanner;

public class ExitLoop2 {

    public static void main(String[] args) {
        char repeat;
        do {
            Scanner in = new Scanner(System.in);
            System.out.println("What is the command keyword to exit a loop in Java?");
            System.out.println("a.int");
            System.out.println("b.continue");
            System.out.println("c.break");
            System.out.println("d.exit");
            System.out.print("Enter your choice: ");
            char choice = in.next().charAt(0);
            if ((choice == 'a') || (choice == 'b') || (choice == 'd')) {
                System.out.println("Incorrect!");
                System.out.println("Again? press y to continue: ");
                repeat = in.next().charAt(0);
            } else {

                System.out.println("Correct !");
                repeat = 'n';
            }
        } while (repeat == 'y');

    }
}

 

 

 

11.By using while loop Write Java program to prompt the user to choose the correct answer from a list of answer choices of a question.

 

The user can choose to continue answering the question or stop answering it. See the example below:

What is the command keyword to exit a loop in Java?

 

a. int

 

b. continue

 

c. break

 

d. exit

 

Enter your choice: b

 

Incorrect!

 

Again? press y to continue:

 

 

package exitloop;

import java.util.Scanner;

public class ExitLoop {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        char repeat = 'y';
        while (repeat == 'y') {
            System.out.println("What is the command keyword to exit a loop in Java?");
            System.out.println("a.int");
            System.out.println("b.continue");
            System.out.println("c.break");
            System.out.println("d.exit");
            System.out.print("Enter your choice:");
            char answer = in.next().charAt(0);
            if ((answer == 'a') || (answer == 'b') || (answer == 'd')) {
                System.out.println("Incorrect !");
                System.out.println("Again? press y to continue: ");
                repeat = in.next().charAt(0);
            } else {
                System.out.println("Correct!");
                repeat = 'n';
            }
        }

    }
}

 

 

 

12.Using a while loop Write a program that asks the user to enter a character then the program displays the character. So on! The program stops only if the user enters the character 't'.

 

 

package enterchar2;

import java.util.Scanner;

public class EnterChar2 {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        char character = 'a';
        while (character != 't') {
            System.out.println("Insert a char: ");
            character = in.next().charAt(0);
            System.out.println("Your character is: " + character);
        }
    }
}

 

 

 

13.Using do while loop Write a program that asks the user to enter a character then the program displays the character. So on! The program stops only if the user enters the character 't'.

 

 

package enterchar;

import java.util.Scanner;

public class EnterChar {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        char character;
        do {
            System.out.println("Insert a char: ");
            character = in.next().charAt(0);
            System.out.println("Your character is: " + character);
        } while (character != 't');
    }
}

 

[MeVsYou]

Nice share for noobies in java.

Although, you have to add the source.

 

The topic moved to the right section!

Edited August 13, 2014 by MeVsYou