calculator.java

此源码为机械工业出版社出版的《Java语言程序设计》第三版所配套的书中所有源代码。

// Calculator.java: Pass parameters from the command line
public class Calculator
{
  // Main method
  public static void main(String[] args)
  {
    // The result of the operation
    int result = 0;

    if (args.length != 3)
    {
      System.out.println(
        "Usage: java Calculator operator operand1 operand2");
      System.exit(0);
    }

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

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