“最后阻止不能正常完成”日食警告

java try-catch-finally

2022-08-31 12:19:48

Eclipse 在下面的代码中给我这个警告：

public int getTicket(int lotteryId, String player) {
    try {
        c = DriverManager.getConnection("jdbc:mysql://" + this.hostname + ":" + this.port + "/" + this.database, this.user, this.password); 
        int ticketNumber;

        PreparedStatement p = c.prepareStatement(
                "SELECT max(num_ticket) " +
                "FROM loteria_tickets " +
                "WHERE id_loteria = ?"
                );
        p.setInt(1, lotteryId);
        ResultSet rs = p.executeQuery();
        if (rs.next()) {
            ticketNumber = rs.getInt(1);
        } else {
            ticketNumber = -1;
        }

        ticketNumber++;

        p = c.prepareStatement(
                "INSERT INTO loteria_tickets " +
                "VALUES (?,?,?,?)");
        p.setInt(1, lotteryId);
        p.setInt(2, ticketNumber);
        p.setString(3, player);
        p.setDate(4, new java.sql.Date((new java.util.Date()).getTime()));
        p.executeUpdate();

        return ticketNumber;
    } catch (Exception e) {
        e.printStackTrace();
    } finally { 
        if (c != null) {
            try {
                c.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return -1;
    }
}

我的代码有什么问题？

答案 1

从中删除返回语句。最终块被认为是清理块，一般不期望返回其中。

答案 2

from “覆盖”进一步的异常引发。returnfinally

public class App {
    public static void main(String[] args) {
        System.err.println(f());
    }
    public static int f() {
        try {
            throw new RuntimeException();
        } finally {
            return 1;
        }
    }
}

1