Why is the return value of args.length 6 when I provide 3 command line arguments for my program

Question

When I provide my Java Command line arguments with this : Calculate 3 * 3 and when I print args.length before making my operations, it returns 6 in the case of a multiplication.

Here is a screenshot of the results for java Calculate 3 * 3

Here is my code in two files:

1. Calculator.java
2. Calculate.java

Here is how to run it if Java is installed:

• Open your terminal, run javac Calculate.java
• When it compiles, run java Calculate 3 * 3

Note: Whenever you try a multiplication for this program, args.length is 6. The program expects one numbers as operands and an operator ("+", "-", "*", "/" for addition, subtraction, multiplication and division respectively). That program works fine for all operations except multiplication.

Calculator.java

import java.util.Map;
import java.util.HashMap;
import java.util.function.BinaryOperator;

public final class Calculator {
  // TODO: Fill this class in.
  private final Map<String, BinaryOperator<Integer>> operators = new HashMap<>();
  
  public void registerOperation(String symbol, BinaryOperator<Integer> operator){
  
    operators.put(symbol.strip(), operator);
  
  }
  
  public int calculate(int a, String operator, int b){
  
    return operators.get(operator).apply(a,b);
    
  }
 
}

Calculate.java

public final class Calculate {
  public static void main(String[] args) {
    System.out.println(args.length);
    System.out.println(args[2]);

    if (args.length != 3) {
      System.out.println("Usage: Calculate [int] [operator] [int]");
      return;
    }

    Calculator calculator = new Calculator();
    // TODO: Register the four "basic" binary operators: +, -, *, /
    calculator.registerOperation("+", (a, b) -> a + b );
    calculator.registerOperation("-", (a, b) -> a - b );
    calculator.registerOperation("*", (a, b) -> a * b );
    calculator.registerOperation("/", (a, b) -> a / b );

    int a = Integer.parseInt(args[0]);
    String operator = args[1];
    int b = Integer.parseInt(args[2]);

    System.out.println(calculator.calculate(a, operator, b));
  }
}

Answer 1

The * has a special meaning (all files in the current directory) to the command interpreter that starts java. This happens for all programs. Quote the *.

java Calculate 3 "*" 3

My advice would be to handle standard input (not arguments).