出于某种原因，我的程序在到达要求用户知道它的考试1分数的部分时会停止。我需要用户能够输入是或否。为什么程序会停止？我需要它才能正常工作。我有所有if-else语句。我可以输入百分比权重，但这就是程序将要执行的所有操作。必须做更多的事情。我的代码远远超出了输入百分比权重。请帮我。
import java.util.Scanner;
public class GradeCalculation {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner grade = new Scanner (System.in);
// A new scanner must be created. The scanner is essential to this program performing properly.
double A = 90-100;
double B = 80-89;
double C = 70-79;
double D = 60-69;
double F = 0-59;
String LetterGrade;
String yes;
String no;
double Exam1, Exam2, finalExam, Labs, Projects, Attendance, Quizzes;
double Exam1Grade, Exam2Grade, finalExamGrade, LabAverage, ProjectsAverage, AttendanceAverage, QuizzesAverage;
double knownWeight;
double PercentageWeights;
// As always, the variables must be declared at the beginning of the program.
System.out.print(
"Grading Scale:\n"+
"A = 90-100 \n"+
"B = 80-89 \n"+
"C = 70-79 \n"+
"D = 60-69 \n"+
"F = 00-59 \n");
System.out.println("What letter grade do you want to achieve in this course?");
LetterGrade = grade.next();
// The user will type the letter grade that it wants in this part.
System.out.println("\nEnter Percentage Weights: \t");
String input = grade.nextLine();
// The string above is needed when the user enters the exam grades and averages.
System.out.print("\n\nExam 1: \t");
Exam1 = grade.nextShort();
System.out.print("\nExam 2: \t");
Exam2 = grade.nextShort();
System.out.print("\nFinal Exam: \t");
finalExam = grade.nextShort();
System.out.print("\nLabs: \t");
Labs = grade.nextShort();
System.out.print("\nProjects: \t");
Projects = grade.nextShort();
System.out.print("\nAttendance: \t");
Attendance = grade.nextShort();
System.out.print("\nQuizzes: \t");
Quizzes = grade.nextShort();
PercentageWeights = (int)(Exam1 + Exam2 + finalExam + Labs + Projects + Attendance + Quizzes);
// The equation above will provide the sum of the percentage weights. Since the variables in the equation were
// originally declared as doubles, I had to put "int" before the actual equation.
if (PercentageWeights > 100 || PercentageWeights < 100) {
System.out.println("\nWeights do not add up to 100. Program exiting. Have a nice day!");
System.exit(0);
}
else {
System.out.println("\nEnter your scores out of a 100: \t");
}
// The part above is very important to continue the rest of the program. If the sum of the percentage weights equals 100,
// the program will continue to run. If the sum is greater than or less than 100, the program will terminate.
System.out.print("\nDo you know your Exam 1 score?");
if (input.equalsIgnoreCase("yes")) {
System.out.print("\nScore received on Exam 1: ");
Exam1Grade = grade.nextDouble();
}
else{
Exam1Grade = 0;
}
System.out.print("\nDo you know your Exam 2 score?");
if (input.equalsIgnoreCase("yes")) {
System.out.print("\nScore received on Exam 2: ");
Exam2Grade = grade.nextDouble();
}
else{
Exam2Grade = 0;
}
System.out.print("\nDo you know your final exam score?");
if (input.equalsIgnoreCase("yes")){
System.out.print("\nScore received on final exam: ");
finalExamGrade = grade.nextDouble();
}
else{
finalExamGrade = 0;
}
System.out.print("\nDo you know your lab average?");
if (input.equalsIgnoreCase("yes")){
System.out.print("\nAverage lab grade: ");
LabAverage = grade.nextDouble();
}
else{
LabAverage = 0;
}
System.out.print("\nDo you know your project average?");
if (input.equalsIgnoreCase("yes")){
System.out.print("\nAverage project grade: ");
ProjectsAverage = grade.nextDouble();
}
else{
ProjectsAverage = 0;
}
System.out.print("\nDo you know your quiz average?");
if (input.equalsIgnoreCase("yes")) {
System.out.print("\nAverage quiz grade: ");
QuizzesAverage = grade.nextDouble();
}
else{
QuizzesAverage = 0;
}
System.out.print("\nDo you know your attendance average?");
if (input.equalsIgnoreCase("yes")){
System.out.print("\nAverage Attendance Grade: ");
AttendanceAverage = grade.nextDouble();
}
else{
AttendanceAverage = 0;
}
// The user has finished answering the questions. Now the program will automatically calculate the data based on
// what the user typed into the program.
double CurrentGrade, avgToFinalLetterGrade, WeightandGrade, finalOverallGrade;
// The doubles above need to be declared in order for the equations below to work properly.
WeightandGrade = (int)((Exam1 * Exam1Grade) + (Exam2 * Exam2Grade) + (finalExam * finalExamGrade) + (Labs * LabAverage) + (Projects * ProjectsAverage) + (Quizzes * QuizzesAverage) + (Attendance * AttendanceAverage));
CurrentGrade = (int)((WeightandGrade) / (Exam1 + Exam2 + finalExam + Labs + Projects + Quizzes + Attendance ));
knownWeight = (Exam1 + Exam2 + finalExam + Labs + Projects + Quizzes + Attendance);
if (grade.equals(A)){
finalOverallGrade = 90;
}
else if (grade.equals(B)){
finalOverallGrade = 80;
}
else if (grade.equals(C)){
finalOverallGrade = 70;
}
else if (grade.equals(D)){
finalOverallGrade = 60;
}
else
finalOverallGrade = F;
avgToFinalLetterGrade = (((100-finalOverallGrade) * (WeightandGrade)) / (100 - knownWeight));
// The equations above are one of the last parts of the program. These equations are critical to determine whether or not the user received its desired letter grade.
// If the desired grade was not reached, the program will give a score that the user must consistently receive in order to possibly reach the desired letter grade.
if (finalOverallGrade >= 90){
System.out.print("Congratulations! You got an A in the class! Hooray!");
}
else if (finalOverallGrade >=80 && finalOverallGrade < 90){
System.out.print("Good job. You got a B in the class!");
}
else if (finalOverallGrade >=70 && finalOverallGrade < 80){
System.out.print("You got a C in the class.");
}
else if (finalOverallGrade >=60 && finalOverallGrade < 70){
System.out.print("You got a D in the class.");
}
else
System.out.print("I'm sorry, but you have a failing grade in the class. May your GPA have mercy on your soul.");
}
}
答案 0 :(得分：2)
这段代码有很多问题。
执行double A=90-100;会将A设为-10;
但是，对于您当前的问题：
你做String input = grade.nextLine();
你永远不会改变输入，因此如果输入不是＆＃34;是＆＃34;，它将跳过获得每个作品的等级。
（您可能还想咨询Using scanner.nextLine()使用scan.nextLine（）与scanner.nextInt或类似的混合[其他陷阱] [总结：如果你做scanner.nextInt，这并不消耗换行符，所以scanner.nextLine（）只会得到那个换行符，而不是你可能期望获得的下一行]）
答案 1 :(得分：0)
input = grade.nextLine()使用用户的“百分比权重”输入读取该行的剩余部分。因此，除非用户先验知识输入“是”，否则input将为空。
即，您需要在input之前使用用户输入更新if (input.equalsIgnoreCase("yes")) {...。