当我尝试打印字符串时，为什么我的程序打印“ .project”？

Question

我应该编写一个输入三个参数的程序，稍后再计算这些参数。 第一个和第三个参数是字符串格式的数字（例如“三个”），而第二个参数是运算符（例如“-”“ +”）。 一切正常，除非我使用“ *”操作。 我尝试在通过解析器功能时打印字符串，因为这是发生错误的地方，并且它以字符串格式打印“ .project”而不是数字。

static int converter(String x)
{
    System.out.println(x); 
    int value = 0;
    String zero = "0";
    String one = "1";
    String two = "2";
    String three = "3";
    String four = "4";
    String five = "5";
    String six = "6";
    String seven = "7";
    String eight = "8";
    String nine = "9";
    String ten = "10";
    String eleven = "11";
    String twelve = "12";
    String thirteen = "13";
    String fourteen = "14";
    String fifteen = "15";
    String sixteen = "16";
    String seventeen = "17";
    String eighteen = "18";
    String nineteen = "19";
    String twenty = "20";
    String thirty = "30";
    String forty = "40";
    String fifty = "50";
    String sixty = "60";
    String seventy = "70";
    String eighty = "80";
    String ninety = "90";
    if(x.compareTo("zero")==0)
        value = Integer.parseInt(zero);
    else if(x.compareTo("one")==0)
        value = Integer.parseInt(one);
    else if(x.compareTo("two")==0)
        value = Integer.parseInt(two);
    else if(x.compareTo("three")==0)
        value = Integer.parseInt(three);
    else if(x.compareTo("four")==0)
        value = Integer.parseInt(four);
    else if(x.compareTo("five")==0)
        value = Integer.parseInt(five);
    else if(x.compareTo("six")==0)
        value = Integer.parseInt(six);
    else if(x.compareTo("seven")==0)
        value = Integer.parseInt(seven);
    else if(x.compareTo("eight")==0)
        value = Integer.parseInt(eight);
    else if(x.compareTo("nine")==0)
        value = Integer.parseInt(nine);
    else if(x.compareTo("ten")==0)
        value = Integer.parseInt(ten);
    else if(x.compareTo("eleven")==0)
        value = Integer.parseInt(eleven);
    else if(x.compareTo("twelve")==0)
        value = Integer.parseInt(twelve);
    else if(x.compareTo("thirteen")==0)
        value = Integer.parseInt(thirteen);
    else if(x.compareTo("fourteen")==0)
        value = Integer.parseInt(fourteen);
    else if(x.compareTo("fifteen")==0)
        value = Integer.parseInt(fifteen);
    else if(x.compareTo("sixteen")==0)
        value = Integer.parseInt(sixteen);
    else if(x.compareTo("seventeen")==0)
        value = Integer.parseInt(seventeen);
    else if(x.compareTo("eighteen")==0)
        value = Integer.parseInt(eighteen);
    else if(x.compareTo("nineteen")==0)
        value = Integer.parseInt(nineteen);
    else if(x.compareTo("twenty")==0)
        value = Integer.parseInt(twenty);
    else if(x.compareTo("thirty")==0)
        value = Integer.parseInt(thirty);
    else if(x.compareTo("forty")==0)
        value = Integer.parseInt(forty);
    else if(x.compareTo("fifty")==0)
        value = Integer.parseInt(fifty);
    else if(x.compareTo("sixty")==0)
        value = Integer.parseInt(sixty);
    else if(x.compareTo("seventy")==0)
        value = Integer.parseInt(seventy);
    else if(x.compareTo("eighty")==0)
        value = Integer.parseInt(eighty);
    else if(x.compareTo("ninety")==0)
        value = Integer.parseInt(ninety);
    else { 
        System.out.println("Error.");
        System.exit(0);
    }
    return value;
}

如果我输入“ *”而不是“ *”，则程序可以正常运行。

Answer 1

因为当您调用程序时，shell会扩展通配符。

考虑之间的相似性

dir *.txt

和

java MyProg.class 2 * 3

星号将替换为目录中的所有文件。