java - 输入年份和第一天，获取一个月的第一天

Question

这是到目前为止我的代码。我想我的做法都是错误的。帮助将不胜感激:

输入年份为 2013 年；天的输入为 2(表示星期二)

public class firstMonthDay {

  public static void main(String[] args) {

    Scanner input= new Scanner(System.in);

    System.out.print("Enter Year:");        
    int year = input.nextInt();

    System.out.print("Enter day of the week:");        
    int inputDay = input.nextInt();

    int firstday=0;        
    int daysInMonth=0;        
    int month =0;

    for (int i=1; i<=365; i++){

      switch(daysInMonth){

      case 1: daysInMonth += 31 ;
      case 2: daysInMonth += 28  ;
      case 3: daysInMonth += 31  ;  
      case 4: daysInMonth += 30  ;  
      case 5: daysInMonth += 31  ;  
      case 6: daysInMonth += 30  ;  
      case 7: daysInMonth += 31  ;  
      case 8: daysInMonth += 31  ;  
      case 9: daysInMonth += 30  ;  
      case 10: daysInMonth += 31 ;  
      case 11: daysInMonth += 30 ;  
      case 12: daysInMonth += 31 ;
        break;
      default:


        switch( firstday=daysInMonth-inputDay%7){
        case 1:System.out.print("Monday");break;
        case 2:System.out.print("Tuesday");break;
        case 3:System.out.print("Wednesday");break;
        case 4:System.out.print("Thursday");break;
        case 5:System.out.print("Friday");break;
        case 6:System.out.print("Saturday");break;
        case 7:System.out.print("Sunday");break;
        default:

          while (month<12){ 
            month++;
            switch(month){
            case 1: System.out.println("January");break;
            case 2: System.out.println("Febuary");break;
            case 3: System.out.println("March"); break;
            case 4: System.out.println("April");break;
            case 5: System.out.println("May");break;
            case 6: System.out.println("June");break;
            case 7: System.out.println("july");break;
            case 8: System.out.println("August");break;
            case 9: System.out.println("September");break;
            case 10: System.out.println("October");break;
            case 11: System.out.println("November");break;
            case 12: System.out.println("December");break;
            default:

            }
          }
        }
      }
      System.out.println("the first day of"+month+"is:"+firstday);
    }
  }      
}

结果应该是

"the first day of january is tuesday"
......
"the first day of december is Sunday"

Answer 1

日历是你的 friend 。

Scanner input= new Scanner(System.in);
System.out.print("Enter Year:");
int year = input.nextInt();
Calendar cal = Calendar.getInstance();
for (int i=0; i<12; i++) {
    cal.set(year, i, 1);
    System.out.printf( "the first day of %s is %s\n",
            cal.getDisplayName(Calendar.MONTH, Calendar.LONG, Locale.getDefault()),
            cal.getDisplayName(Calendar.DAY_OF_WEEK, Calendar.LONG, Locale.getDefault()) );
}//end for i