小编Soc*_*etM的帖子

HY,

我有以下代码:

import java.io.*;
import java.util.ArrayList;
import java.util.Scanner;
import java.util.regex.*;

/
public  class RegexSimple4
{

     public static void main(String[] args) {   

          try {
              Scanner myfis = new Scanner(new File("D:\\myfis32.txt"));
              ArrayList <String> foundaz = new ArrayList<String>();
              ArrayList <String> noduplicates = new ArrayList<String>();

              while(myfis.hasNext()) {
                  String line = myfis.nextLine();
                  String delim = " ";
                  String [] words = line.split(delim);

                  for (String s : words) {                    
                      if (!s.isEmpty() && s != null) {
                          Pattern pi = Pattern.compile("[aA-zZ]*");
                          Matcher ma = pi.matcher(s);

                          if (ma.find()) …

我有一个Heroku PostgreSQL数据库,我无法从Java连接.我尝试了不同的方法但没有成功.

下面是我的Java代码:

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;



public class MainConfig {

    public static void main(String[] args) {

     try{
         dataSource();
         System.out.println("conected");
     }
    catch(Exception ex){
        ex.printStackTrace();
    }
    }

    public static Connection dataSource() throws URISyntaxException, SQLException {

        String ConnectionString ="jdbc:postgresql://l********n:cPd7VRjIhNVWOrZ4uWEeZWKYqV@ec2-184-73-251-115.compute-1.amazonaws.com:5432/dac36a93ohuvsd";
        String username = "****";
        String password = "***";

        return DriverManager.getConnection(ConnectionString, username, password);
    }

}

我在控制台中遇到的错误是:

> org.postgresql.util.PSQLException: The connection attempt failed.
    at org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:233)
    at org.postgresql.core.ConnectionFactory.openConnection(ConnectionFactory.java:64)
    at org.postgresql.jdbc2.AbstractJdbc2Connection.<init>(AbstractJdbc2Connection.java:144)
    at org.postgresql.jdbc3.AbstractJdbc3Connection.<init>(AbstractJdbc3Connection.java:29)
    at org.postgresql.jdbc3g.AbstractJdbc3gConnection.<init>(AbstractJdbc3gConnection.java:21)
    at org.postgresql.jdbc4.AbstractJdbc4Connection.<init>(AbstractJdbc4Connection.java:31)
    at org.postgresql.jdbc4.Jdbc4Connection.<init>(Jdbc4Connection.java:24)
    at org.postgresql.Driver.makeConnection(Driver.java:410)
    at org.postgresql.Driver.connect(Driver.java:280)
    at java.sql.DriverManager.getConnection(Unknown …

你能解释一下为什么下面显示的方法是由Java编译和运行的

public static void testIf(int v){
   if (v < 10)   

   if (v >20 )  
     System.out.println(" 20 IF");
   else        
     System.out.println(" 20 ELSE");

   else        
     System.out.println("10 Else");
}

• 通常每个IF应该与最接近的ELSE链接,为什么最后的其他不是悬空的ELSE？此外,IF与之相关.
• 最后一个ELSE无法访问,为什么允许它？

预先感谢您的帮助.

此致