Java泛型中对象比较的陷阱：为何条件语句失效及equals()方法的正确使用

public static <T> void gpa(T[] elements) {
    for (T element : elements) {
        // 尝试比较泛型元素与字符串字面量
        if (element == "A") { // 错误：比较引用，且类型不匹配
            // ...
        }
        // ...
    }
}

import java.util.Objects; // 引入Objects工具类，用于null安全比较

class Calculation {
    public static <T> void gpa(T[] elements) {
        if (elements == null || elements.length == 0) {
            System.out.println("Input array is empty or null.");
            return;
        }

        int[] gradesValue = new int[elements.length]; // 存储每个元素的对应分数
        int sum = 0;

        System.out.println("Processing grades:");
        for (int i = 0; i < elements.length; i++) {
            T element = elements[i];
            System.out.println("Original element: " + element);

            if (element instanceof Character) {
                // 如果是Character类型，将其转换为char进行比较
                char gradeChar = (Character) element;
                switch (gradeChar) {
                    case 'A': gradesValue[i] = 9; break;
                    case 'B': gradesValue[i] = 8; break;
                    case 'C': gradesValue[i] = 7; break;
                    case 'D': gradesValue[i] = 6; break;
                    case 'E': gradesValue[i] = 5; break;
                    case 'F': gradesValue[i] = 2; break;
                    default: gradesValue[i] = 0; // 未知等级
                }
                System.out.println("  Mapped to score: " + gradesValue[i]);

            } else if (element instanceof Integer) {
                // 如果是Integer类型，将其转换为int进行比较
                int gradeInt = (Integer) element;
                // 根据分数反向映射等级，或直接使用分数
                gradesValue[i] = gradeInt; // 直接使用传入的整数作为分数
                // 打印对应的等级信息
                switch (gradeInt) {
                    case 9: System.out.println("  Mapped to grade: A"); break;
                    case 8: System.out.println("  Mapped to grade: B"); break;
                    case 7: System.out.println("  Mapped to grade: C"); break;
                    case 6: System.out.println("  Mapped to grade: D"); break;
                    case 5: System.out.println("  Mapped to grade: E"); break;
                    case 2: System.out.println("  Mapped to grade: F"); break;
                    default: System.out.println("  Mapped to grade: Unknown");
                }
            } else {
                System.out.println("  Unsupported element type: " + element.getClass().getName());
                gradesValue[i] = 0; // 对于不支持的类型，分数记为0
            }
        }

        // 计算总分
        for (int score : gradesValue) {
            sum += score;
        }

        // 计算平均分
        double average = (double) sum / elements.length;
        System.out.println("The total score is: " + sum);
        System.out.println("The average score is: " + String.format("%.2f", average));
    }
}

public class Calc {
    public static void main(String[] args) {
        Calculation obj = new Calculation();

        Character[] arr1 = {'A', 'B', 'C', 'A', 'A'};
        Integer[] arr2 = {9, 9, 5, 2, 8};

        System.out.println("--- Processing CGPA for Character Grades ---");
        obj.gpa(arr1);

        System.out.println("\n--- Processing CGPA for Integer Scores ---");
        obj.gpa(arr2);
    }
}