06 Java Fundamentals

Output in Java

By Dummy for Dummies

Output in Java

Alright, fellow monkeys, we've learned how to take input. Now let's talk about giving output back. You already know print from earlier:

System.out.println("Hello, World!");

That same line handles every kind of output, just with small changes depending on what you need. Here they are, with the golden lines in focus:

1. Simple Output

public class Main {
    public static void main(String[] args) {
        System.out.print("Hello, World!");
    }
}

• System.out: System gives output
• print: Print the content ahead
• ("Hello, World!"): The content inside bracket is printed

Another way to print it is:

public class Main {
    public static void main(String[] args) {
        System.out.print("Hello");
        System.out.print("World");
    }
}

Therefore, we need a way to print content across different lines for better readability.

2. Output with Next Line

public class Main {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}

• println: Print the content ahead and go to next line

3. Output with Variable

public class Main {
    public static void main(String[] args) {
        int age = 20;
        System.out.println("Your age: " + age);
    }
}

• "Your age: ": Prints this as it is
• +: Join the content on right to content on left (called concatenation)
• age: Joins whatever is inside the variable as it is no matter what datatype

4. Formatted Output

Formatted output lets you print things in a specific layout. Concatenation with + doesn't work here. Here's a demonstration:

public class Main {
    public static void main(String[] args) {
        int age = 20;
        System.out.printf("Your age: %d", age);
    }
}

• "Your age: ": Prints this as it is
• %d: Reserve space for integer variable
• ,: Tells Java to place the variables on right in reserved spaces
• age: Variable that is to be placed in reserved places

Placeholders for Each Datatype

Extra Things for Styling

• \n: Since println does not work here we use \n for next line
• \t: Prints tab space
• \": Since quotations are used to represent string, to print quotation inside string use backslash with them
• \\: To print a backslash use another backslash with it

Complete Example

public class OutputDemo {
    public static void main(String[] args) {
        int age = 20;
        double gpa = 3.75;
        char grade = 'A';
        String name = "Hassan";
        boolean pass = true;

        System.out.printf("Student Details:\n");
        System.out.printf("Name:\t%s\n", name);
        System.out.printf("Age:\t%d\n", age);
        System.out.printf("GPA:\t%.2f\n", gpa);
        System.out.printf("Grade:\t%c\n", grade);
        System.out.printf("Passed:\t%b\n", pass);

        System.out.printf("Quote Example:\t\"Work hard, dream big!\"\n");
        System.out.printf("Backslash Example:\tC:\\Users\\Hassan\n");
    }
}

Exercise

We have covered enough topics to go for an exercise. In this exercise I want you to study this code, break it down, analyze it and identify the concepts used here. It would be even better if you write down your observations and make a mini report on it. You can extend the program to accept a second student and print both reports.

import java.util.Scanner;

public class Exercise {
    public static void main(String[] args) {
        System.out.println("Welcome to Java Fundamentals Exercise!");
        System.out.println("Let's practice everything we have learned so far.\n");

        String name;
        int age;
        double gpa;
        char grade;
        boolean pass;

        Scanner input = new Scanner(System.in);

        System.out.print("Enter your name: ");
        name = input.nextLine();

        System.out.print("Enter your age: ");
        age = input.nextInt();

        System.out.print("Enter your GPA: ");
        gpa = input.nextDouble();

        System.out.print("Enter your grade (A-F): ");
        grade = input.next().charAt(0);

        System.out.print("Did you pass the last exam? (true/false): ");
        pass = input.nextBoolean();

        System.out.println("\n    GENERATING REPORT\n");

        int nextYearAge = age + 1;
        boolean isAdult = age >= 18;
        boolean eligible = isAdult && pass;

        System.out.printf("Student Report for %s\n", name);
        System.out.printf("Age: %d (Next year: %d)\n", age, nextYearAge);
        System.out.printf("GPA: %.2f\n", gpa);
        System.out.printf("Grade: %c\n", grade);
        System.out.printf("Passed: %b\n", pass);
        System.out.printf("Are you an adult? %b\n", isAdult);
        System.out.printf("Eligible for next level? %b\n", eligible);

        input.close();
    }
}

Mini Project: Student Report Card

Build a Java program that works like a student report card. It should:

• Ask for the student's name and marks in three subjects (integers or decimals)
• Calculate the total and the average of the marks
• Decide pass or fail: pass if the average is 40 or more, and none of the marks is zero

Finally, print a formatted report using printf. The report must include:

• Student's name
• Each subject mark
• Total marks
• Average (2 decimal places)
• Result: PASS or FAIL

While writing the program, use a Scanner method for each data type, plus arithmetic, relational, and logical operators, and printf with placeholders like %s, %d, %.2f.

Example Output

Closing

That's it for Output in Java! We now know how to make our program talk back, whether it's a single word, a full sentence, or a nicely formatted report.