Java:不打印以特定字符开头的行

Question

所以基本上我想做的是从gree1out文件中读取信息，其中包含以下信息:

1|1

2|0

以下代码片段连接到我的 mySQL 数据库，使用前 2 个数字(“|”之前)来获取 xf.user.user_id。

当前字符串打印是:

equalsdavid 1 6af87ef8-e620-4d08-8320-183fc469eb0d

user 0 ac899bce-4a87-4977-957c-05013534b25b

我需要一种方法来删除字符串第二部分小于 1 的行。现在我尝试做类似的事情，但既然我在这里，你可能会说它不起作用:

  temp = temp.replaceAll("(?m)^0.*", "");

这是代码:

  package io.chuchoter.stats2;

    import java.io.*;
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.sql.Statement;
    import java.util.UUID;

    import io.chuchoter.core.Main;

    public class RATE2_agree {
    public static void main(String [] args) {

        String line = null;
     
        try {
            
            PrintStream p = new PrintStream(new File(Main.agree2out));
            System.setOut(p);
            
            FileReader fileReader = 
                new FileReader(Main.agree1out);

            BufferedReader bufferedReader = 
                new BufferedReader(fileReader);

            while((line = bufferedReader.readLine()) != null) {
                
                String[] parts = line.split("|");
                String part1 = parts[0];
                String part3 = parts[2];
                
                Connection con = DriverManager.getConnection(Main.host, Main.uName, Main.uPass);
                
                Statement rstmt = con.createStatement();
                String r = "SELECT * FROM `xf_user` WHERE `user_id` = " + part1 + ";";
                ResultSet rs = rstmt.executeQuery(r);
                
                while (rs.next()) {
                    String uuid = UUID.randomUUID().toString();
                    String username = rs.getString("username");
                    
                    String print = username + " " + part3 + " " + uuid;
                    System.out.println(print);
                }
            }   

            bufferedReader.close();         
                  
        }
        
        catch(FileNotFoundException ex) {
            System.out.println("Unable to open file");                
        }
        catch(IOException ex) {
            System.out.println(
                "Error reading file");
        }
        
        catch (SQLException err) {
            System.out.println(err.getMessage());
        }
    }

}

感谢您的帮助!

Answer 1

对于字符串“1|1”，当您应用拆分时

String[] parts = line.split("|");

你得到一个大小为 2 的数组。因此你的代码将像这样

String[] parts = line.split("|");
String part1 = parts[0];
String part3 = parts[1];         
Connection con = DriverManager.getConnection(Main.host, Main.uName, Main.uPass);

Statement rstmt = con.createStatement();
String r = "SELECT * FROM `xf_user` WHERE `user_id` = " + part1 + ";";
ResultSet rs = rstmt.executeQuery(r);

StringBuilder sb = new StringBuilder();
while (rs.next()) {
     String uuid = UUID.randomUUID().toString();
     String username = rs.getString("username");
     String print = username + " " + part3 + " " + uuid;
     if(Integer.parseInt(part3) >= 0)
         sb.append(print + "\n");
}
System.out.println(sb.toString());

希望这有帮助!