java:不能从静态上下文中引用非静态变量错误
以下代码在变量上产生了错误,con2说 "non-static variable con2 cannot be referenced from a static context Error."
我用Google搜索解决方案,并且他们暗示尚未初始化该变量以使方法可用。我初始化不正确吗?我也尝试过将事情改为公开,但这也无济于事。
import java.io.*;import java.net.*;
import java.sql.*;
import java.sql.CallableStatement;
import java.sql.ResultSet;
import java.sql.PreparedStatement;
import net.sourceforge.jtds.jdbcx.JtdsDataSource;
import net.sourceforge.jtds.jdbc.Driver;
class testconnect {
private java.sql.Connection con2 = null;
private final String url2 = "jdbc:jtds:sqlserver://";
private final String serverName= "SQL01";
private final String portNumber = "2677";
private final String databaseName= "App";
private final String userName = "bob";
private final String password = "boob";
private final String selectMethod = "cursor";
private String getConnectionUrl2(){
System.out.println("initalizing jtds");
//String returnVal = url+serverName+":"+portNumber+";databaseName="+databaseName+";user="+userName+";password="+password+";instance="+instance+";";
String returnVal = url2+serverName+":"+portNumber+"/"+databaseName+";user="+userName+";password="+password;
System.out.println("url2: " + returnVal);
return returnVal;
}
public static void main (String[] args) {
con2 = java.sql.DriverManager.getConnection(getConnectionUrl2());
}
} //end class
回答:
不,实际上,你必须声明con2字段为静态:
private static java.sql.Connection con2 = null;
编辑:更正,实际上是远远不够的,你将遇到相同的问题,因为getConnection2Url方法也不是静态的。更好的解决方案可能是改为进行以下更改:
public static void main (String[] args) { new testconnect().run();
}
public void run() {
con2 = java.sql.DriverManager.getConnection(getConnectionUrl2());
}
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