萬花筒

// Fig. 3.7: GradeBook.java

// GradeBook class that contains a courseName instance variable

// and methods to set and get its value.

// U3 P.103

public class GradeBook
{                       ↓實體變數
   private String courseName; // course name for this GradeBook

   //method to set the course name
   public void setCourseName ( String name )
   {               ↑用來設定屬性courseName內容值的set方法
      courseName = name; // store the course name
   } // end method setCourseName

   // method to retrieve the course name
   public String getCourseName ()
   {                  ↑用來提領屬性courseName內容值的get方法
      return courseName;
   } // end method getCourseName

   // display a welcome message to the GradBook user
   public void displayMessage()
   {
      // this statement calls getCourseName to get the
      // name of the course this GradeBook represents
      System.out.printf ("Welcome to the grade book for \n%s!\n",getCourseName() );
   } // end method displaymessage                                              ↑呼叫get的方法

}  // end class GradeBook

圖3.7　包含了一個 courseName 實體變數的 GradeBook 類別


java.GradeBook
出現：Exception in thread "main" java.lang.NoSuchMethodError: main