Question

我有一个包含以下内容的数据库：

title of the show:
Avenger
Deadpool
etc.

我有一个方法可以获得节目的所有标题

    public String shows2(){
    try{
        Class.forName("com.mysql.jdbc.Driver");
        Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/ticket","root",null);
        Statement stmt = conn.createStatement();
        ResultSet rs = stmt.executeQuery("select * from events");  
        while(rs.next()){
            String title = rs.getString("title");
            return "Shows: " +title;
        }
    }catch(Exception e){
        e.printStackTrace();
    }
    return "something";
}

但是当我使用这个方法时，它只返回一行/ show

"Shows: Avenger"

Answer 1

您必须返回List<String>而不是单String。

public List<String> shows2(){
    List<String> result = new ArrayList<>();
    try{
        Class.forName("com.mysql.jdbc.Driver");
        Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/ticket","root",null);
        Statement stmt = conn.createStatement();
        ResultSet rs = stmt.executeQuery("select * from events");  
        while(rs.next()){
            String title = rs.getString("title");
            result.add(title);
        }
    }catch(Exception e){
        e.printStackTrace();
    }
    return result;
}

Answer 2

将public String shows2(){更改为public List<String> shows2(){，以便您可以返回完整的结果列表

并且不会在while循环中返回，而是添加到您的List，例如yourList.add(title);然后在方法结束时返回。

Answer 3

希望这会对你有所帮助

    public ArrayList<String> shows2() {
    ArrayList<String> movieList = new ArrayList<String>();
    try {
        Class.forName("com.mysql.jdbc.Driver");
        Connection conn = DriverManager.getConnection(
                "jdbc:mysql://localhost:3306/ticket", "root", null);
        Statement stmt = conn.createStatement();
        ResultSet rs = stmt.executeQuery("select * from events");
        while (rs.next()) {
            String title = rs.getString("title");
            movieList.add("Shows: " + title);
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
    return movieList;
}

如何从方法返回所有Resultset值。 Java的

3 个答案: