Retrieve column names from java.sql.ResultSet

With java.sql.ResultSet is there a way to get a column's name as a String by using the column's index? I had a look through the API doc but I can't find anything.

You can get this info from the ResultSet metadata. See ResultSetMetaData

e.g.

 ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM TABLE2");
 ResultSetMetaData rsmd = rs.getMetaData();
 String name = rsmd.getColumnName(1);

and you can get the column name from there. If you do

select x as y from table

then rsmd.getColumnLabel() will get you the retrieved label name too.

In addition to the above answers, if you're working with a dynamic query and you want the column names but do not know how many columns there are, you can use the ResultSetMetaData object to get the number of columns first and then cycle through them.

Amending Brian's code:

ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM TABLE2");
ResultSetMetaData rsmd = rs.getMetaData();
int columnCount = rsmd.getColumnCount();

// The column count starts from 1
for (int i = 1; i <= columnCount; i++ ) {
  String name = rsmd.getColumnName(i);
  // Do stuff with name
}

You can use the the ResultSetMetaData (http://java.sun.com/javase/6/docs/api/java/sql/ResultSetMetaData.html) object for that, like this:

ResultSet rs = stmt.executeQuery("SELECT * FROM table");
ResultSetMetaData rsmd = rs.getMetaData();
String firstColumnName = rsmd.getColumnName(1);

This question is old and so are the correct previous answers. But what I was looking for when I found this topic was something like this solution. Hopefully it helps someone.

// Loading required libraries    
import java.util.*;
import java.sql.*;

public class MySQLExample {
  public void run(String sql) {
    // JDBC driver name and database URL
    String JDBC_DRIVER = "com.mysql.jdbc.Driver";
    String DB_URL = "jdbc:mysql://localhost/demo";

    // Database credentials
    String USER = "someuser"; // Fake of course.
    String PASS = "somepass"; // This too!

    Statement stmt = null;
    ResultSet rs = null;
    Connection conn = null;
    Vector<String> columnNames = new Vector<String>();

    try {
      // Register JDBC driver
      Class.forName(JDBC_DRIVER);

      // Open a connection
      conn = DriverManager.getConnection(DB_URL, USER, PASS);

      // Execute SQL query
      stmt = conn.createStatement();
      rs = stmt.executeQuery(sql);
      if (rs != null) {
        ResultSetMetaData columns = rs.getMetaData();
        int i = 0;
        while (i < columns.getColumnCount()) {
          i++;
          System.out.print(columns.getColumnName(i) + "\t");
          columnNames.add(columns.getColumnName(i));
        }
        System.out.print("\n");

        while (rs.next()) {
          for (i = 0; i < columnNames.size(); i++) {
            System.out.print(rs.getString(columnNames.get(i))
                + "\t");

          }
          System.out.print("\n");
        }

      }
    } catch (Exception e) {
      System.out.println("Exception: " + e.toString());
    }

    finally {
      try {
        if (rs != null) {
          rs.close();
        }
        if (stmt != null) {
          stmt.close();
        }
        if (conn != null) {
          conn.close();
        }
      } catch (Exception mysqlEx) {
        System.out.println(mysqlEx.toString());
      }

    }
  }
}