附加字符串的怪异行为

Question

我正在使用以下代码来生成对象的文本转储：

public static String generateText(Quiz quiz){
    String endResult = "";
    for (QuizQuestion question : quiz.getQuestions()) {
        endResult += question.getQuestion();
        endResult += System.lineSeparator();
        endResult += question.getAnswer1();
        endResult += System.lineSeparator();
        endResult += question.getAnswer2();
        endResult += System.lineSeparator();
        endResult += question.getAnswer3();
        endResult += System.lineSeparator();
        endResult += question.getAnswer4();
        endResult += System.lineSeparator();
        endResult += question.getCorrectAnswer();
        endResult += System.lineSeparator();
    }

    return endResult;
}

但是，当我将endResult打印到文件tis时，输出是：

questiona1a2a3a4a

然后它打印4空行。如何解决？