Using + to Join Text and Numbers

• In Java, the + symbol is used to join (combine) text and numbers when displaying output.
• This process is called string concatenation (which simply means “joining text together”).
• Example:

public class joinTextnNum{
  public static void main(String[] args) {
    int age = 20;
    System.out.println("I am " + age + " years old.");
  }
}
    

Output: I am 20 years old.

• Java automatically converts the number 20 into text and joins it with "I am " and " years old.".

• Example 2: Performing Calculations Before Joining

If we want to perform a calculation before displaying the result, we must use parentheses ().

public class joinTextnNum{
  public static void main(String[] args) {
    int num = 10;
    System.out.println("Double of " + num + " is " + (num * 2));

  }
}
    

Output: Double of 10 is 20

• Java calculates num * 2 first (because of the parentheses), then joins it with the text.

⚠️ Common Mistake

If you forget the parentheses, Java will join the text first, then add the number as text instead of doing the math:

public class joinTextnNum{
  public static void main(String[] args) {
    System.out.println("10 + 5 = " + 10 + 5);
  }
}
    

Output: 10 + 5 = 105

✅ Fix: Use parentheses () to ensure the calculation happens first:

public class joinTextnNum{
  public static void main(String[] args) {
    System.out.println("10 + 5 = " + (10 + 5));
  }
}
    

Output: 10 + 5 = 15

int num = 10;
System.out.println("Double of " + num + " is " + (num * 2));

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