結果集

要建立一個 ResultSet，你應該建立一個 Statement 或 PrepapredStatement：

使用 Statement 建立 ResultSet

try {
    Class.forName(driver);
    Connection connection = DriverManager.getConnection(
            "jdbc:somedb://localhost/databasename", "username", "password");
    Statement statement = connection.createStatement();
    ResultSet result = statement.executeQuery("SELECT * FROM my_table");

} catch (ClassNotFoundException | SQLException e) {
}

使用 PrepapredStatement 建立 ResultSet

try {
    Class.forName(driver);
    Connection connection = DriverManager.getConnection(
            "jdbc:somedb://localhost/databasename", "username", "password");
    PreparedStatement preparedStatement = connection.prepareStatement("SELECT * FROM my_table");
    ResultSet result = preparedStatement.executeQuery();

} catch (ClassNotFoundException | SQLException e) {
}

檢查 ResultSet 是否包含資訊

if (result.next()) {
   //yes result not empty                
}

從 ResultSet 獲取資訊

你可以從 ResultSet 獲得幾種型別的資訊，例如 String, int, boolean, float, Blob，…獲取你必須使用迴圈或簡單資訊的資訊：

if (result.next()) {
    //get int from your result set
    result.getInt("id");
    //get string from your result set
    result.getString("username");
    //get boolean from your result set
    result.getBoolean("validation");
    //get double from your result set
    result.getDouble("price");
}