无法弄清楚为什么继续收到空指针异常

Question

忙于JDBC项目并遇到问题。我正在尝试从主类调用插入方法。但是当我运行时，我不断收到一个空指针异常。

public static final String INSERT_ONE_RECORD = "INSERT INTO " + TABLE_AUTHORS + "(" + COLUMN_AUTHORS_AUTHOR + ")" +
            " VALUE (?)";

private Connection connection;

public void insertOneRecord (String author){

        try {

            insertOneRecordPrepStmt = connection.prepareStatement(INSERT_ONE_RECORD);
            insertOneRecordPrepStmt.setString(1,author);
            insertOneRecordPrepStmt.executeUpdate();
            System.out.println("insert author went");
        } catch (SQLException e) {
            System.out.println("insert author failed"+ e.getMessage());
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        AuthorRepository authorRepository = new AuthorRepository();
        authorRepository.insertOneRecord("George");
    }

运行时，我得到：

Exception in thread "main" java.lang.NullPointerException
    at unasat.Repositories.AuthorRepository.insertOneRecord(AuthorRepository.java:57)
    at unasat.Repositories.AuthorRepository.main(AuthorRepository.java:85)