类型不匹配：无法从元素类型Object转换为String JDBC MetaData

My Code

我的代码

public static ArrayList getTablesMetadata() throws SQLException{
    String table[] = {"TABLE"};
    ResultSet rs = null;
    ArrayList tables = null;

    rs = metadata.getTables(null, null, null, table);
    tables = new ArrayList();
    while(rs.next()){
        tables.add(rs.getString("TABLE_NAME"));
    }
    return tables;
}

public static void getColumnsMetadata(ArrayList tables)
        throws SQLException{
    ResultSet rs = null;

    for(String actualTable : tables){  <-----------------------------------
        rs = metadata.getColumns(null, null, actualTable, null);
        System.out.println(actualTable.toUpperCase());
        while(rs.next()){
            System.out.println(rs.getString("COLUMN_NAME")+ " "
                    + rs.getString("TYPE_NAME")+ " "
                    + rs.getString("COLUMN_SIZE"));
        }
        System.out.println("\n");
    }
}
public static ArrayList getTab