Java 什么'；我的代码GPA计算有什么问题吗

我的GPA计算器的代码昨天运行良好，但现在返回错误：

package problemset.leveltwo;

import java.util.*;

public class gpaCalculator {

public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);

    double mathGPA = 0;
    double historyGPA = 0;
    double englishGPA = 0;
    double scienceGPA = 0;
    double langGPA = 0;

    // A+
    double a = 4.00;

    // A-
    double b = 3.70;

    // B+
    double c = 3.30;

    // B
    double d = 3.00;

    // B-
    double e = 2.70; 

    // C+
    double f = 2.30;

    // C
    double g = 2.00;

    // C-
    double h = 1.70;

    // D+
    double i = 1.30;

    // D
    double j = 1.00;

    // D-
    double k = 0.70;

    // F
    double l = 0;

    System.out.println("Enter Your Math Grade (percentage)");
    int mathGrade = scanner.nextInt();

    System.out.println("Enter Your History Grade (percentage)");
    int historyGrade = scanner.nextInt();

    System.out.println("Enter Your English Grade (percentage)");
    int englishGrade = scanner.nextInt();

    System.out.println("Enter Your Science Grade (percentage)");
    int scienceGrade = scanner.nextInt();

    System.out.println("Enter Your Language Grade (percentage)");
    int langGrade = scanner.nextInt();

    // MATH GRADE

    // Math = A
    if (mathGrade >= 96) {
        System.out.println("Math GPA = " + a);
        mathGPA = 4.00;
        }

    // Math = A-
    if (mathGrade < 96) {
        if (mathGrade >= 90) {
            System.out.println("Math GPA = " + b);
            mathGPA = 3.70;
        }
    }

    // Math B+
    if (mathGrade < 90) {
        if (mathGrade >= 86) {
            System.out.println("Math GPA = " + c);
            mathGPA = 3.30;
        }
    }

    // Math B
    if (mathGrade < 86) {
        if (mathGrade >= 84) {
            System.out.println("Math GPA = " + d);
            mathGPA = 3.00;
        }
    }

    // Math B-
    if (mathGrade < 84) {
        if (mathGrade >= 80) {
            System.out.println("Math GPA = " + e);
            mathGPA = 2.70;
        }
    }

    // Math C+
    if (mathGrade < 80) {
        if (mathGrade >= 76) {
            System.out.println("Math GPA = " + f);
            mathGPA = 2.30;
        }
    }

    // Math C
    if (mathGrade < 76) {
        if (mathGrade >= 73) {
            System.out.println("Math GPA = " + g);
            mathGPA = 2.00;
        }
    }

    // Math C-
    if (mathGrade < 73) {
        if (mathGrade >= 70) {
            System.out.println("Math GPA = " + h);
            mathGPA = 1.70;
        }
    }

    // Math D+
    if (mathGrade < 70) {
        if (mathGrade >= 66) {
            System.out.println("Math GPA = " + i);
            mathGPA = 1.30;
        }
    }

    // Math D
    if (mathGrade < 66) {
        if (mathGrade >= 63) {
            System.out.println("Math GPA = " + j);
            mathGPA = 1.00;
        }
    }

    // Math D-
    if (mathGrade < 63) {
        if (mathGrade >= 50) {
            System.out.println("Math GPA = " + k);
            mathGPA = 0.70;
        }
    }

    // Math F
    if (mathGrade < 50) {
        System.out.println("Math GPA = " + l);
        mathGPA = 0.00;
    }



    // HISTORY GRADE

    // History = A
    if (historyGrade >= 96) {
        System.out.println("History GPA = " + a);
        historyGPA = 4.00;
        }

    // History = A-
    if (historyGrade < 96) {
        if (historyGrade >= 90) {
            System.out.println("History GPA = " + b);
            historyGPA = 3.70;
        }
    }

    // History B+
    if (historyGrade < 90) {
        if (historyGrade >= 86) {
            System.out.println("History GPA = " + c);
            historyGPA = 3.30;
        }
    }

    // History B
    if (historyGrade < 86) {
        if (historyGrade >= 84) {
            System.out.println("History GPA = " + d);
            historyGPA = 3.00;
        }
    }

    // History B-
    if (historyGrade < 84) {
        if (historyGrade >= 80) {
            System.out.println("History GPA = " + e);
            historyGPA = 2.70;
        }
    }

    // History C+
    if (historyGrade < 80) {
        if (historyGrade >= 76) {
            System.out.println("History GPA = " + f);
            historyGPA = 2.30;
        }
    }

    // History C
    if (historyGrade < 76) {
        if (historyGrade >= 73) {
            System.out.println("History GPA = " + g);
            historyGPA = 2.00;
        }
    }

    // History C-
    if (historyGrade < 73) {
        if (historyGrade >= 70) {
            System.out.println("History GPA = " + h);
            historyGPA = 1.70;
        }
    }

    // History D+
    if (historyGrade < 70) {
        if (historyGrade >= 66) {
            System.out.println("History GPA = " + i);
            historyGPA = 1.30;
        }
    }

    // History D
    if (historyGrade < 66) {
        if (historyGrade >= 63) {
            System.out.println("History GPA = " + j);
            historyGPA = 1.00;
        }
    }

    // History D-
    if (historyGrade < 63) {
        if (historyGrade >= 50) {
            System.out.println("History GPA = " + k);
            historyGPA = 0.70;
        }
    }

    // History F
    if (historyGrade < 50) {
        System.out.println("History GPA = " + l);
        historyGPA = 0;
        }


    // ENGLISH GRADE

    // English = A
            if (englishGrade >= 96) {
                System.out.println("English GPA = " + a);
                englishGPA = 4.00;
                }

            // English = A-
            if (englishGrade < 96) {
                if (englishGrade >= 90) {
                    System.out.println("English GPA = " + b);
                    englishGPA = 3.70;
                }
            }

            // English B+
            if (englishGrade < 90) {
                if (englishGrade >= 86) {
                    System.out.println("English GPA = " + c);
                    englishGPA = 3.30;
                }
            }

            // English B
            if (englishGrade < 86) {
                if (englishGrade >= 84) {
                    System.out.println("English GPA = " + d);
                    englishGPA = 3.00;
                }
            }

            // English B-
            if (englishGrade < 84) {
                if (englishGrade >= 80) {
                    System.out.println("English GPA = " + e);
                    englishGPA = 2.70;
                }
            }

            // English C+
            if (englishGrade < 80) {
                if (englishGrade >= 76) {
                    System.out.println("English GPA = " + f);
                    englishGPA = 2.30;
                }
            }

            // English C
            if (englishGrade < 76) {
                if (englishGrade >= 73) {
                    System.out.println("English GPA = " + g);
                    englishGPA = 2.00;
                }
            }

            // English C-
            if (englishGrade < 73) {
                if (englishGrade >= 70) {
                    System.out.println("English GPA = " + h);
                    englishGPA = 1.70;
                }
            }

            // English D+
            if (englishGrade < 70) {
                if (englishGrade >= 66) {
                    System.out.println("English GPA = " + i);
                    englishGPA = 1.30;
                }
            }

            // English D
            if (englishGrade < 66) {
                if (englishGrade >= 63) {
                    System.out.println("English GPA = " + j);
                    englishGPA = 1.00;
                }
            }

            // English D-
            if (englishGrade < 63) {
                if (englishGrade >= 50) {
                    System.out.println("English GPA = " + k);
                    englishGPA = 0.70;
                }
            }

            // English F
            if (englishGrade < 50) {
                System.out.println("English GPA = " + l);
                englishGPA = 0;
                }


            // SCIENCE GRADE

            // Science = A
            if (scienceGrade >= 96) {
                System.out.println("Science GPA = " + a);
                scienceGPA = 4.00;
                }

            // Science = A-
            if (scienceGrade < 96) {
                if (scienceGrade >= 90) {
                    System.out.println("Science GPA = " + b);
                    scienceGPA = 3.70;
                }
            }

            // Science B+
            if (scienceGrade < 90) {
                if (scienceGrade >= 86) {
                    System.out.println("Science GPA = " + c);
                    scienceGPA = 3.30;
                }
            }

            // Science B
            if (scienceGrade < 86) {
                if (scienceGrade >= 84) {
                    System.out.println("Science GPA = " + d);
                    scienceGPA = 3.00;
                }
            }

            // Science B-
            if (scienceGrade < 84) {
                if (scienceGrade >= 80) {
                    System.out.println("Science GPA = " + e);
                    scienceGPA = 2.70;
                }
            }

            // Science C+
            if (scienceGrade < 80) {
                if (scienceGrade >= 76) {
                    System.out.println("Science GPA = " + f);
                    scienceGPA = 2.30;
                }
            }

            // Science C
            if (scienceGrade < 76) {
                if (scienceGrade >= 73) {
                    System.out.println("Science GPA = " + g);
                    scienceGPA = 2.00;
                }
            }

            // Science C-
            if (scienceGrade < 73) {
                if (scienceGrade >= 70) {
                    System.out.println("Science GPA = " + h);
                    scienceGPA = 1.70;
                }
            }

            // Science D+
            if (scienceGrade < 70) {
                if (scienceGrade >= 66) {
                    System.out.println("Science GPA = " + i);
                    scienceGPA = 1.30;
                }
            }

            // Science D
            if (scienceGrade < 66) {
                if (scienceGrade >= 63) {
                    System.out.println("Science GPA = " + j);
                    scienceGPA = 1.00;
                }
            }

            // Science D-
            if (scienceGrade < 63) {
                if (scienceGrade >= 50) {
                    System.out.println("Science GPA = " + k);
                    scienceGPA = 0.70;
                }
            }

            // Science F
            if (scienceGrade < 50) {
                System.out.println("Science GPA = " + l);
                scienceGPA = 0;
                }


            // LANGUAGE GRADE

            // Lang = A
            if (langGrade >= 96) {
                System.out.println("Language GPA = " + a);
                langGPA = 4.00;
                }

            // Lang = A-
            if (langGrade < 96) {
                if (langGrade >= 90) {
                    System.out.println("Language GPA = " + b);
                    langGPA = 3.70;
                }
            }

            // lang B+
            if (langGrade < 90) {
                if (langGrade >= 86) {
                    System.out.println("Language GPA = " + c);
                    langGPA = 3.30;
                }
            }

            // Lang B
            if (langGrade < 86) {
                if (langGrade >= 84) {
                    System.out.println("Language GPA = " + d);
                    langGPA = 3.00;
                }
            }

            // Lang B-
            if (langGrade < 84) {
                if (langGrade >= 80) {
                    System.out.println("Language GPA = " + e);
                    langGPA = 2.70;
                }
            }

            // Lang C+
            if (langGrade < 80) {
                if (langGrade >= 76) {
                    System.out.println("Language GPA = " + f);
                    langGPA = 2.30;
                }
            }

            // Lang C
            if (langGrade < 76) {
                if (langGrade >= 73) {
                    System.out.println("Language GPA = " + g);
                    langGPA = 2.00;
                }
            }

            // Lang C-
            if (langGrade < 73) {
                if (langGrade >= 70) {
                    System.out.println("Language GPA = " + h);
                    langGPA = 1.70;
                }
            }

            // Lang D+
            if (langGrade < 70) {
                if (langGrade >= 66) {
                    System.out.println("Language GPA = " + i);
                    historyGPA = 1.30;
                }
            }

            // Lang D
            if (langGrade < 66) {
                if (langGrade >= 63) {
                    System.out.println("Language GPA = " + j);
                    langGPA = 1.00;
                }
            }

            // Lang D-
            if (langGrade < 63) {
                if (langGrade >= 50) {
                    System.out.println("Language GPA = " + k);
                    langGPA = 0.70;
                }
            }

            // Lang F
            if (langGrade < 50) {
                System.out.println("Language GPA = " + l);
                langGPA = 0;
                }


    //Credits taken = 12-17

    System.out.println("Math Worth (credits):");
    int mathWorth = scanner.nextInt();

    System.out.println("History Worth (credits):");
    int historyWorth = scanner.nextInt();

    System.out.println("English Worth (credits):");
    int englishWorth = scanner.nextInt();

    System.out.println("Science Worth (credits):");
    int scienceWorth = scanner.nextInt();

    System.out.println("Language Worth (credits):");
    int langWorth = scanner.nextInt();

    double newMath = mathGPA * mathWorth;
    double newHistory = historyGPA * historyWorth;
    double newEnglish = englishGPA * englishWorth;
    double newScience = scienceGPA * scienceWorth;
    double newLang = langGPA * langWorth;

    int creditsTaken = mathWorth + historyWorth + englishWorth + scienceWorth + langWorth;

    double total = (newMath + newHistory + newEnglish + newScience + newLang) / creditsTaken;
    System.out.println("Total GPA = " + total);

    }

}

---

如果有人能告诉我这些错误意味着什么以及如何修复它们，我将非常感激。提前谢谢

运行时类路径上似乎缺少您的类。这个类的包和名称是什么？您如何运行程序（命令行、bat、sh、IDE等等）？@BorisŠuška包是package problemset.leveltwo；类的名称是gpaCalculator no，类的名称是gpaCalculator。Java是区分大小写的语言。您的文件名是gpaCalculator.java吗？你是这样运行程序的：用鼠标右键点击文件，点运行方式。。。然后选择Java应用程序？它将在eclipse中运行您的应用程序。您是否重命名了昨天的文件或类？

Exception in thread "main" java.lang.NoClassDefFoundError:             problemset/leveltwo/gpaCalculator
Caused by: java.lang.ClassNotFoundException: problemset.leveltwo.gpaCalculator
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)