calculator.java

JAVA程序设计导论那本书上的一些源代码. 在学那本书的下来的

public class Calculator {
  /** Main method */
  public static void main(String[] args) {
    // Check command-line arguments
    if (args.length != 3) {
      System.out.println(
        "Usage: java Calculator operand1 operator operand2");
      System.exit(0);
    }

    // The result of the operation
    int result = 0;

    // Determine the operator
    switch (args[1].charAt(0)) {
      case '+': result = Integer.parseInt(args[0]) +
                         Integer.parseInt(args[2]);
                break;
      case '-': result = Integer.parseInt(args[0]) -
                         Integer.parseInt(args[2]);
                break;
      case '*': result = Integer.parseInt(args[0]) *
                         Integer.parseInt(args[2]);
                break;
      case '/': result = Integer.parseInt(args[0]) /
                         Integer.parseInt(args[2]);
    }

    // Display result
    System.out.println(args[0] + ' ' + args[1] + ' ' + args[2]
      + " = " + result);
  }
}