Java Output

Output Methods

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

System.out.print("Hello ");
System.out.print("World");

System.out.printf("Age: %d", 25);

String.format("Hello %s", "Java");

🔹 System.out.println()

The most commonly used output method:

public class PrintlnExample {
    public static void main(String[] args) {
        // Print different data types
        System.out.println("This is a string");
        System.out.println(42);              // Integer
        System.out.println(3.14);            // Double
        System.out.println(true);            // Boolean
        System.out.println('A');             // Character
        
        // Print variables
        String name = "John";
        int age = 25;
        System.out.println("Name: " + name);
        System.out.println("Age: " + age);
        
        // Print expressions
        System.out.println("Sum: " + (10 + 20));
        System.out.println("Is adult: " + (age >= 18));
    }
}

🔹 System.out.print()

Print without automatic line breaks:

public class PrintExample {
    public static void main(String[] args) {
        // Print on same line
        System.out.print("Hello ");
        System.out.print("World ");
        System.out.print("from ");
        System.out.print("Java!");
        
        // Add manual line break
        System.out.println();  // Empty println for new line
        
        // Mix print and println
        System.out.print("Your score: ");
        System.out.println(95);
        
        // Print numbers in sequence
        for (int i = 1; i <= 5; i++) {
            System.out.print(i + " ");
        }
        System.out.println();  // New line after loop
    }
}

🔹 System.out.printf()

Formatted output with placeholders:

public class PrintfExample {
    public static void main(String[] args) {
        String name = "Alice";
        int age = 28;
        double salary = 75000.50;
        boolean isManager = true;
        
        // Basic formatting
        System.out.printf("Name: %s\n", name);           // %s for String
        System.out.printf("Age: %d\n", age);             // %d for integer
        System.out.printf("Salary: %.2f\n", salary);     // %.2f for 2 decimal places
        System.out.printf("Manager: %b\n", isManager);   // %b for boolean
        
        // Multiple values in one statement
        System.out.printf("Employee: %s, Age: %d, Salary: $%.2f\n", 
                         name, age, salary);
        
        // Number formatting
        System.out.printf("Percentage: %d%%\n", 85);     // %% for literal %
        System.out.printf("Padded number: %05d\n", 42);  // Pad with zeros
        System.out.printf("Right aligned: %10s|\n", "Hi"); // Right align in 10 spaces
        System.out.printf("Left aligned: %-10s|\n", "Hi"); // Left align in 10 spaces
    }
}

🔹 String Concatenation

Combine strings and values for output:

public class ConcatenationExample {
    public static void main(String[] args) {
        String firstName = "John";
        String lastName = "Doe";
        int age = 30;
        double height = 5.9;
        
        // Using + operator
        System.out.println("Full name: " + firstName + " " + lastName);
        System.out.println("Age: " + age + " years old");
        System.out.println("Height: " + height + " feet");
        
        // Concatenating with calculations
        System.out.println("Next year age: " + (age + 1));
        System.out.println("Height in inches: " + (height * 12));
        
        // Multiple data types
        System.out.println("Info: " + firstName + " is " + age + 
                          " years old and " + height + " feet tall");
        
        // Using StringBuilder for efficiency (advanced)
        StringBuilder sb = new StringBuilder();
        sb.append("Name: ").append(firstName).append(" ").append(lastName);
        System.out.println(sb.toString());
    }
}

🔹 Escape Sequences

Special characters for formatting output:

public class EscapeExample {
    public static void main(String[] args) {
        // New line
        System.out.println("First line\nSecond line");
        
        // Tab spacing
        System.out.println("Name:\tJohn\nAge:\t25");
        
        // Quotes in strings
        System.out.println("He said, \"Hello World!\"");
        System.out.println("It's a beautiful day");
        
        // Backslash
        System.out.println("File path: C:\\Users\\Documents\\");
        
        // Multiple escape sequences
        System.out.println("Quote:\t\"Java is awesome!\"\n\t- A programmer");
    }
}