与对象和构造函数一起使用的Java

Question

我的教授已经给出了一个由多位构造函数创建Monthnum类来完成所有参数的任务，因为我们正在学习面向对象编程。我需要创建一个新的构造函数，它接受用户输入作为一个int值，另一个构造函数接受它作为一年中的字符串值。例如：1 = 1月和1月= 1。我知道我可以在我的主要方法中创建扫描仪，但我不确定如何让此号码被接受并打印出来。在正确的直接步骤将是非常有用的！

import java.util.Scanner; 

public class learningObjectsAndClasses { 
    public static void main(String args[]){ 

    Scanner input = new Scanner(System.in); 
    int monthNumber = input.nextInt(); 
    String monthName = input.nextLine(); 
    Monthnum inputMonthNumber = new Monthnum(monthNumber); 
    Monthnum inputMonthName = new Monthnum(monthName); 
    System.out.println("Please enter the month name or number: " 
     + inputMonthNumber);  

    } 
} 
class Monthnum{ 

    int Monthnum; 
    String monthName; 


    Monthnum(){ 
     Monthnum = 1; 
    } 
    Monthnum(int whichMonth){ 
     Monthnum = whichMonth; 
     if (whichMonth == 1){ 
      System.out.println("January"); 
     } 
     else if (whichMonth == 2){ 
      System.out.println("February"); 
     } 
     else if (whichMonth == 3){ 
      System.out.println("March"); 
     } 
     else if (whichMonth == 4){ 
      System.out.println("April"); 
     } 
     else if (whichMonth == 5){ 
      System.out.println("May"); 
     } 
     else if (whichMonth == 6){ 
      System.out.println("June"); 
     } 
     else if (whichMonth == 7){ 
      System.out.println("July"); 
     } 
     else if (whichMonth == 8){ 
      System.out.println("August"); 
     } 
     else if (whichMonth == 9){ 
      System.out.println("September"); 
     } 
     else if (whichMonth == 10){ 
      System.out.println("October"); 
     } 
     else if (whichMonth == 11){ 
      System.out.println("November"); 
     } 
     else if (whichMonth == 12){ 
      System.out.println("December"); 
     } 
     else 
      System.out.println("Invalid input"); 

     } 
    Monthnum(String whichMonth){ 
     if (whichMonth == "January"){ 
      Monthnum = 1; 
     } 
     else if (whichMonth == "February"){ 
      Monthnum = 2; 
     } 
     else if (whichMonth == "March"){ 
      Monthnum = 3; 
     } 
     else if (whichMonth == "April"){ 
      Monthnum = 3; 
     } 
     else if (whichMonth == "May"){ 
      Monthnum = 4; 
     } 
     else if (whichMonth == "June"){ 
      Monthnum = 5; 
     } 
     else if (whichMonth == "July"){ 
      Monthnum = 6; 
     } 
     else if (whichMonth == "August"){ 
      Monthnum = 7; 
     } 
     else if (whichMonth == "September"){ 
      Monthnum = 8; 
     } 
     else if (whichMonth == "October"){ 
      Monthnum = 9; 
     } 
     else if (whichMonth == "November"){ 
      Monthnum = 10; 
     } 
     else if (whichMonth == "December"){ 
      Monthnum = 11; 
     } 
     else if (whichMonth == "March"){ 
      Monthnum = 12; 
     } 
     else 
      System.out.println("Invalid input"); 
    } 
} 

Answer 1

因此，您安装扫描仪和一切后。您想要读取用户输入的值。你会用Scanner's .nextInt()方法读取它。

Scanner input = new Scanner(System.in); 
int num; 
num = input.nextInt(); 

然后阅读它并将它保存在一个变量num后，可以实例Monthnum的对象为您从用户得到了一个给定的参数。

Monthnum m = new Monthnum(num); 

如果你想读取用户的字符串，可以用户Scanner's nextLine()方法是这样的：

Scanner input = new Scanner(System.in); //Same scanner from above 
             //no need to initialize it again 
String s; 
s = input.nextLine(); 

现在，你将宣布与String参数初始化Monthnum的对象（你的避风港还没有发表）

Monthnum p = new Monthnum(s); 

现在这里是一个提示，使该构造函数。如果你已经拥有这些东西，你可以使用它们。只要改变他们是这样的：

if (whichMonth.equals("January"){ 
     System.out.println("a"); 
} 
.... 

如果你不明白的东西问我问题！感谢

编辑：所以现在你的代码应该是这样的：

package tst; 

import java.util.Scanner; 

public class learningObjectsAndClasses { 
public static void main(String args[]){ 

    Scanner input = new Scanner(System.in); 

    System.out.println("Enter Month Name "); 
    String monthName = input.next(); 
    Monthnum inputMonthNumber = new Monthnum(monthName); 

    System.out.println("Enter Number "); 
    int monthNumber = input.nextInt(); 
    Monthnum inputMonthName = new Monthnum(monthNumber); 

} 
public static class Monthnum{ 

    public int Monthnum; 
    public String monthName; 


    public Monthnum(){ 
     Monthnum = 1; 
     monthName = "January"; 
    } 
    public Monthnum(int whichMonth){ 
     Monthnum = whichMonth; 
     if (whichMonth == 1){ 
      monthName = "January"; 
      System.out.println("January"); 
     } 
     else if (whichMonth == 2){ 
      monthName = "February"; 
      System.out.println("February"); 
     } 
     else if (whichMonth == 3){ 
      monthName = "March"; 
      System.out.println("March"); 
     } 
     else if (whichMonth == 4){ 
      monthName = "April"; 
      System.out.println("April"); 
     } 
     else if (whichMonth == 5){ 
      monthName = "May"; 
      System.out.println("May"); 
     } 
     else if (whichMonth == 6){ 
      monthName = "June"; 
      System.out.println("June"); 
     } 
     else if (whichMonth == 7){ 
      monthName = "July"; 
      System.out.println("July"); 
     } 
     else if (whichMonth == 8){ 
      monthName = "August"; 
      System.out.println("August"); 
     } 
     else if (whichMonth == 9){ 
      monthName = "September"; 
      System.out.println("September"); 
     } 
     else if (whichMonth == 10){ 
      monthName = "October"; 
      System.out.println("October"); 
     } 
     else if (whichMonth == 11){ 
      monthName = "November"; 
      System.out.println("November"); 
     } 
     else if (whichMonth == 12){ 
      monthName = "December"; 
      System.out.println("December"); 
     } 
     else { 
      System.out.println("Invalid input from int cons"); 
     } 

    } //end of cons 

    public Monthnum(String whichMonth){ 
     if (whichMonth.equals("January")){ 
      Monthnum = 1; 
      System.out.println(Monthnum); 
     } 
     else if (whichMonth.equals("February")){ 
      Monthnum = 2; 
      System.out.println(Monthnum); 
     } 
     else if (whichMonth.equals("March")){ 
      Monthnum = 3; 
      System.out.println(Monthnum); 
     } 
     else if (whichMonth.equals("April")){ 
      Monthnum = 4; 
      System.out.println(Monthnum); 
     } 
     else if (whichMonth.equals("May")){ 
      Monthnum = 5; 
      System.out.println(Monthnum); 
     } 
     else if (whichMonth.equals("June")){ 
      Monthnum = 6; 
      System.out.println(Monthnum); 
     } 
     else if (whichMonth.equals("July")){ 
      Monthnum = 7; 
      System.out.println(Monthnum); 
     } 
     else if (whichMonth.equals("August")){ 
      Monthnum = 8; 
      System.out.println(Monthnum); 
     } 
     else if (whichMonth.equals("September")){ 
      Monthnum = 9; 
      System.out.println(Monthnum); 
     } 
     else if (whichMonth.equals("October")){ 
      Monthnum = 10; 
      System.out.println(Monthnum); 
     } 
     else if (whichMonth.equals("November")){ 
      Monthnum = 11; 
      System.out.println(Monthnum); 
     } 
     else if (whichMonth.equals("December")){ 
      Monthnum = 12; 
      System.out.println(Monthnum); 
     } 
     else 
      System.out.println("Invalid input"); 
    } 
    } 
}