什么是argv？

Question

  public static void main(String[] argv) {

      Connection connection = DatabaseDriverExtender.connectOrCreateDataBase();
      if (connection == null) {
        System.out.print("NOOO");
      }
      try {
        //TODO Check what is in argv 
        //If it is -1
        /*
         * TODO This is for the first run only!
         * Add this code:
         * DatabaseDriverExtender.initialize(connection);
         * Then add code to create your first account, an administrator with a password
         * Once this is done, create an employee account as well.
         * 
         */

如何检查argv中的内容？我对此并不熟悉。

我假设它检查数据库是否已经创建。如果它没有创建-1。我如何检查argv中的内容并找到它的-1？

argv是一个String []？

Answer 1

是的，＆＃34; argv＆＃34;只是一个String数组。

对于你的代码，你可以做类似的事情：

if (argv.length > 0) {
//check if argv[0].equals("-1") or something like that
}

Answer 2

String [] argv是一个字符串的集合，由空格分隔，可以在终端上输入程序。您可以在此链接上找到有关它的更多详细信息：

What is "String args[]"? parameter in main method Java

Answer 3

//when using main method argv cannot be null. But if using somehwere else check if array is not null and then access the elements
public static void main(String[] argv) {
    int len=argv.length;
    System.out.println("No. of elements :"+len);
    for(int i=0; i<len; i++){
        String indexValue=argv[i];
        System.out.println("Array Index value:"+indexValue);
        if("-1".equals(indexValue)){
            //value is -1
        }else{
            //value is not -1
        }
    }
}