grades1.java

这是JAVA入门程序

import javax.swing.JOptionPane;
class Grades1{
	public static void main(String[] args){
		final double ENGLISH_MIDTERM_PERCENTAGE = .25;
		final double ENGLISH_FINALEXAM_PERCENTAGE = .25;
		final double ENGLISH_RESEARCH_PERCENTAGE = .30;
		final double ENGLISH_PRESENTATION_PERCENTAGE = .20;
		
		final double MATH_MIDTERM_PERCENTAGE = .50;
		final double MATH_FINALEXAM_PERCENTAGE = .50;
		
		final double SCIENCE_MIDTERM_PERCENTAGE = .40;
		final double SCIENCE_FINALEXAM_PERCENTAGE = .40;
		final double SCIENCE_RESEARCH_PERCENTAGE = .20;
		
		int midterm = 0;
		int research = 0;
		int finalExam = 0;
		int presentation = 0;
		
		double finalNumericGrade = 0;
		String finalLetterGrade = "";
		String response;
		
		//what type of student are we calculating?
	  response = JOptionPane.showInputDialog("Please choose the type of student you want to\n"+
	  																				"(1=English;2=Math;3=Science):");
		
		if(response == null){
			JOptionPane.showMessageDialog(null,"You have clicked on the Cancle button!");
			//System.exit(0);
		}
		else if(response.equals("")){
			JOptionPane.showMessageDialog(null,"You must choose the type of student first!");
			//System.exit(0);
		}
		else if(Integer.parseInt(response)<1|Integer.parseInt(response)>3){
			JOptionPane.showMessageDialog(null,"You are enterring the invalid student type!");
			System.exit(0);	
		}
		
		//Student type is valid ,now let's calculate the grade;
		
		switch(Integer.parseInt(response)){
			//Case 1 is for Enlish student
			case 1:
							midterm = Integer.parseInt(JOptionPane.showInputDialog("Enter the Midterm grade:"));
							finalExam = Integer.parseInt(JOptionPane.showInputDialog("Enter the final exam grade:"));
							research = Integer.parseInt(JOptionPane.showInputDialog("Enter the research grade:"));
							presentation = Integer.parseInt(JOptionPane.showInputDialog("Enter the presentation grade:"));
							
							finalNumericGrade = (midterm*ENGLISH_MIDTERM_PERCENTAGE)+
																	(finalExam*ENGLISH_FINALEXAM_PERCENTAGE)+
																	(research*ENGLISH_RESEARCH_PERCENTAGE)+
																	(presentation*ENGLISH_PRESENTATION_PERCENTAGE);
							if(finalNumericGrade >= 93)
								finalLetterGrade = "A";
							else if((finalNumericGrade >= 85)&(finalNumericGrade < 93))
								finalLetterGrade = "B";
							else if((finalNumericGrade >= 78)&(finalNumericGrade < 85))
								finalLetterGrade = "C";
							else if((finalNumericGrade >= 70)&(finalNumericGrade < 78))
								finalLetterGrade = "D";
							else
								finalLetterGrade = "F";
							
							JOptionPane.showMessageDialog(null,"***ENGLISH STUDENT***\n\n"+
								"Midterm grade is:"+midterm+"\n"+
								"Final Exam grade is:"+finalExam+"\n"+
								"Research grade is:"+research+"\n"+
								"Presentation grade is:"+presentation+"\n\n"+
								"Final Numeric grade is:"+finalNumericGrade+"\n"+
								"Final Letter Grade is:"+finalLetterGrade);
							break;
				//Case 2 is a Math student;
				case 2:
								midterm = Integer.parseInt(JOptionPane.showInputDialog("Enter the midterm grade:"));										
								finalExam = Integer.parseInt(JOptionPane.showInputDialog("Enter the final exam grade:"));
								
								finalNumericGrade = (midterm*MATH_MIDTERM_PERCENTAGE)+(finalExam*MATH_FINALEXAM_PERCENTAGE);
								
								if(finalNumericGrade > 90)
									finalLetterGrade = "A";
								else if((finalNumericGrade >= 83)&(finalNumericGrade < 90))
									finalLetterGrade = "B";
								else if((finalNumericGrade >= 76)&(finalNumericGrade < 83))
								  finalLetterGrade = "C";
								else if((finalNumericGrade >= 65)&(finalNumericGrade < 76))
									finalLetterGrade = "D";
								else 
									finalLetterGrade = "F";
									
								JOptionPane.showMessageDialog(null,"***MATH STUDENT***\n\n"+
								"Midterm grade is:"+midterm+"\n"+
								"Final Exam grade is:"+finalExam+"\n"+								
								"Final Numeric grade is:"+finalNumericGrade+"\n"+
								"Final Letter Grade is:"+finalLetterGrade);
							break;
				//Case 3 is a Science Student;
				case 3:
								midterm = Integer.parseInt(JOptionPane.showInputDialog("Enter the midterm grade:"));
								finalExam = Integer.parseInt(JOptionPane.showInputDialog("Enter the final exam grade:"));
								research = Integer.parseInt(JOptionPane.showInputDialog("Enter the research grade:"));
								
								finalNumericGrade = (midterm*SCIENCE_MIDTERM_PERCENTAGE)+(finalExam*SCIENCE_FINALEXAM_PERCENTAGE)+
																		(research*SCIENCE_RESEARCH_PERCENTAGE);
								
								if (finalNumericGrade >= 90)
										finalLetterGrade = "A";
								else
								if((finalNumericGrade >=80)&(finalNumericGrade < 90))
										finalLetterGrade = "B";
								else
								if((finalNumericGrade >=70) & (finalNumericGrade < 80))
										finalLetterGrade = "C";
								else
								if((finalNumericGrade >= 60)&(finalNumericGrade < 70))
										finalLetterGrade = "D";
								else
										finalLetterGrade = "F";
								
								JOptionPane.showMessageDialog(null,"***SCIENCE STUDENT***\n\n"+
												"Midterm grade is:"+midterm+"\n"+
												"Final Exam is:"+finalExam+"\n"+
												"Research grade is:"+research+"\n\n"+
												"Final Numeric Grade is:"+finalNumericGrade+"\n"+
												"Final Letter Grade is:"+finalLetterGrade);
								break;
								
				default:
								JOptionPane.showMessageDialog(null,response+"-is not a valid student type!");
								System.exit(0);						
			  
																		
		}
		
		System.exit(0);
	}
}