Question

realm1.beginTransaction();
                                        newuser tripnew = realm1.createObject(newuser.class);
 int nid= (int)(realm.where(newuser.class).max("nid").intValue()+1);
  tripnew.setNid(nid);

                                        tripnew.setFrom(frominput.getText().toString());
                                        tripnew.setTo(toinput.getText().toString());
                                        tripnew.setDatejourney(dateinput.getText().toString());
   realm1.commitTransaction();
     updatetrip();


    /// iam also use this code not working
    realm.where(newuser.class).maximumInt("id_cp") + 1;

newuser.java //////

public class newuser extends RealmObject {



   private  String from,to,datejourney;

    public String getFrom() {
        return from;
    }

    public void setFrom(String from) {
        this.from = from;
    }

    public String getTo() {
        return to;
    }

    public void setTo(String to) {
        this.to = to;
    }

    public String getDatejourney() {
        return datejourney;
    }

    public void setDatejourney(String datejourney) {
        this.datejourney = datejourney;
    }


}

Answer 1

您的班级看起来没有import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import java.util.ArrayList; import com.mysql.jdbc.Statement; public class Fire_Emblem { public static ArrayList<String> GetCharacters() { try { Class.forName("com.mysql.jdbc.Driver"); java.sql.Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/fire_emblem","root","[redacted]"); java.sql.Statement st = con.createStatement(); ResultSet rs = st.executeQuery("select name from characters"); System.out.println ("Connection successful"); ArrayList<String> list = new ArrayList<String>(); while (rs.next()) { list.add(rs.getString("name")); } System.out.println(list); } catch (SQLException e) { System.out.println(e.getMessage()); System.out.println("Connection failed"); } return list; }或@Parameters ({"browser"})数字字段。添加nid字段和访问者，然后id_cp应该适用于大多数情况。但是，如果数据库中没有int nid;实例，它将失败。我使用singleton factory for generating primary keys作为更通用的解决方案。

如果您需要更多上下文，可以在Realm Git Hub中进行长时间的讨论：Document how to set an auto increment id?

如何在android领域中使用自动增量

1 个答案: