Getting multiple table schema and returning them, using one helper method
$begingroup$
I want to get two distinct sets of schema from a database without having to create multiple Connection/PreparedStatement/ResultSet objects.
Currently, I have a helper method that queries the database, gets each individual schema, and then returns them together in one ArrayList - please refer to the code below.
private ArrayList<ArrayList<?>> getAttributesAndGroups() {
ArrayList<ArrayList<?>> retList = new ArrayList<ArrayList<?>>();
Connection conn = null;
try {
Class.forName("com.mysql.cj.jdbc.Driver");
conn = DriverManager.getConnection(jdbcUrl, userId, password);
ArrayList<Attribute> listAttrs = new ArrayList<Attribute>();
String query = "select aid, aname from tbl_attributes order by aid";
PreparedStatement ps = conn.prepareStatement(query);
ResultSet rs = ps.executeQuery();
while (rs.next()) {
int aid = rs.getInt(1);
String aname = rs.getString(2);
Attribute attr = new Attribute(aid, aname);
listAttrs.add(attr);
}
retList.add(listAttrs);
ArrayList<Group> listGroups = new ArrayList<Group>();
query = "select gid, gname from tbl_groups order by gid";
ps = conn.prepareStatement(query);
rs = ps.executeQuery();
while (rs.next()) {
int gid = rs.getInt(1);
String gname = rs.getString(2);
Group grp = new Group(gid, gname);
listGroups.add(grp);
}
retList.add(listGroups);
rs.close();
ps.close();
} catch (Exception e) {
log.error("Exception", e);
} finally {
if (conn != null) {
try {
conn.close();
} catch (Exception e) {
//
}
}
}
return retList;
}
Where I call my helper method, I do the following:
ArrayList<ArrayList<?>> lists = getAttributesAndGroups();
ArrayList<Attribute> listAttrs = (ArrayList<Attribute>) lists.get(ATTRIBUTES);
request.setAttribute("listAttrs", listAttrs);
ArrayList<Group> listGroups = (ArrayList<Group>) lists.get(GROUPS);
request.setAttribute("listGroups", listGroups);
request.getRequestDispatcher("addUser.jsp").forward(request, response);
(ATTRIBUTES and GROUPS are simple integer constants representing 0 and 1 respectively.)
However, my code is giving me warnings of Type safety: Unchecked cast from ArrayList<capture#1-of ?> to ArrayList<Attribute> (ditto for the other line).
Is there a better approach for what I want to do?
java
asked 5 mins ago
user10931326user10931326
1
New contributor
user10931326 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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$endgroup$
add a comment |
$begingroup$
I want to get two distinct sets of schema from a database without having to create multiple Connection/PreparedStatement/ResultSet objects.
Currently, I have a helper method that queries the database, gets each individual schema, and then returns them together in one ArrayList - please refer to the code below.
private ArrayList<ArrayList<?>> getAttributesAndGroups() {
ArrayList<ArrayList<?>> retList = new ArrayList<ArrayList<?>>();
Connection conn = null;
try {
Class.forName("com.mysql.cj.jdbc.Driver");
conn = DriverManager.getConnection(jdbcUrl, userId, password);
ArrayList<Attribute> listAttrs = new ArrayList<Attribute>();
String query = "select aid, aname from tbl_attributes order by aid";
PreparedStatement ps = conn.prepareStatement(query);
ResultSet rs = ps.executeQuery();
while (rs.next()) {
int aid = rs.getInt(1);
String aname = rs.getString(2);
Attribute attr = new Attribute(aid, aname);
listAttrs.add(attr);
}
retList.add(listAttrs);
ArrayList<Group> listGroups = new ArrayList<Group>();
query = "select gid, gname from tbl_groups order by gid";
ps = conn.prepareStatement(query);
rs = ps.executeQuery();
while (rs.next()) {
int gid = rs.getInt(1);
String gname = rs.getString(2);
Group grp = new Group(gid, gname);
listGroups.add(grp);
}
retList.add(listGroups);
rs.close();
ps.close();
} catch (Exception e) {
log.error("Exception", e);
} finally {
if (conn != null) {
try {
conn.close();
} catch (Exception e) {
//
}
}
}
return retList;
}
Where I call my helper method, I do the following:
ArrayList<ArrayList<?>> lists = getAttributesAndGroups();
ArrayList<Attribute> listAttrs = (ArrayList<Attribute>) lists.get(ATTRIBUTES);
request.setAttribute("listAttrs", listAttrs);
ArrayList<Group> listGroups = (ArrayList<Group>) lists.get(GROUPS);
request.setAttribute("listGroups", listGroups);
request.getRequestDispatcher("addUser.jsp").forward(request, response);
(ATTRIBUTES and GROUPS are simple integer constants representing 0 and 1 respectively.)
However, my code is giving me warnings of Type safety: Unchecked cast from ArrayList<capture#1-of ?> to ArrayList<Attribute> (ditto for the other line).
Is there a better approach for what I want to do?
java
asked 5 mins ago
user10931326user10931326
1
New contributor
user10931326 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
add a comment |
$begingroup$
I want to get two distinct sets of schema from a database without having to create multiple Connection/PreparedStatement/ResultSet objects.
Currently, I have a helper method that queries the database, gets each individual schema, and then returns them together in one ArrayList - please refer to the code below.
private ArrayList<ArrayList<?>> getAttributesAndGroups() {
ArrayList<ArrayList<?>> retList = new ArrayList<ArrayList<?>>();
Connection conn = null;
try {
Class.forName("com.mysql.cj.jdbc.Driver");
conn = DriverManager.getConnection(jdbcUrl, userId, password);
ArrayList<Attribute> listAttrs = new ArrayList<Attribute>();
String query = "select aid, aname from tbl_attributes order by aid";
PreparedStatement ps = conn.prepareStatement(query);
ResultSet rs = ps.executeQuery();
while (rs.next()) {
int aid = rs.getInt(1);
String aname = rs.getString(2);
Attribute attr = new Attribute(aid, aname);
listAttrs.add(attr);
}
retList.add(listAttrs);
ArrayList<Group> listGroups = new ArrayList<Group>();
query = "select gid, gname from tbl_groups order by gid";
ps = conn.prepareStatement(query);
rs = ps.executeQuery();
while (rs.next()) {
int gid = rs.getInt(1);
String gname = rs.getString(2);
Group grp = new Group(gid, gname);
listGroups.add(grp);
}
retList.add(listGroups);
rs.close();
ps.close();
} catch (Exception e) {
log.error("Exception", e);
} finally {
if (conn != null) {
try {
conn.close();
} catch (Exception e) {
//
}
}
}
return retList;
}
Where I call my helper method, I do the following:
ArrayList<ArrayList<?>> lists = getAttributesAndGroups();
ArrayList<Attribute> listAttrs = (ArrayList<Attribute>) lists.get(ATTRIBUTES);
request.setAttribute("listAttrs", listAttrs);
ArrayList<Group> listGroups = (ArrayList<Group>) lists.get(GROUPS);
request.setAttribute("listGroups", listGroups);
request.getRequestDispatcher("addUser.jsp").forward(request, response);
(ATTRIBUTES and GROUPS are simple integer constants representing 0 and 1 respectively.)
However, my code is giving me warnings of Type safety: Unchecked cast from ArrayList<capture#1-of ?> to ArrayList<Attribute> (ditto for the other line).
Is there a better approach for what I want to do?
java
asked 5 mins ago
user10931326user10931326
1
New contributor
user10931326 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
I want to get two distinct sets of schema from a database without having to create multiple Connection/PreparedStatement/ResultSet objects.
Currently, I have a helper method that queries the database, gets each individual schema, and then returns them together in one ArrayList - please refer to the code below.
private ArrayList<ArrayList<?>> getAttributesAndGroups() {
ArrayList<ArrayList<?>> retList = new ArrayList<ArrayList<?>>();
Connection conn = null;
try {
Class.forName("com.mysql.cj.jdbc.Driver");
conn = DriverManager.getConnection(jdbcUrl, userId, password);
ArrayList<Attribute> listAttrs = new ArrayList<Attribute>();
String query = "select aid, aname from tbl_attributes order by aid";
PreparedStatement ps = conn.prepareStatement(query);
ResultSet rs = ps.executeQuery();
while (rs.next()) {
int aid = rs.getInt(1);
String aname = rs.getString(2);
Attribute attr = new Attribute(aid, aname);
listAttrs.add(attr);
}
retList.add(listAttrs);
ArrayList<Group> listGroups = new ArrayList<Group>();
query = "select gid, gname from tbl_groups order by gid";
ps = conn.prepareStatement(query);
rs = ps.executeQuery();
while (rs.next()) {
int gid = rs.getInt(1);
String gname = rs.getString(2);
Group grp = new Group(gid, gname);
listGroups.add(grp);
}
retList.add(listGroups);
rs.close();
ps.close();
} catch (Exception e) {
log.error("Exception", e);
} finally {
if (conn != null) {
try {
conn.close();
} catch (Exception e) {
//
}
}
}
return retList;
}
Where I call my helper method, I do the following:
ArrayList<ArrayList<?>> lists = getAttributesAndGroups();
ArrayList<Attribute> listAttrs = (ArrayList<Attribute>) lists.get(ATTRIBUTES);
request.setAttribute("listAttrs", listAttrs);
ArrayList<Group> listGroups = (ArrayList<Group>) lists.get(GROUPS);
request.setAttribute("listGroups", listGroups);
request.getRequestDispatcher("addUser.jsp").forward(request, response);
(ATTRIBUTES and GROUPS are simple integer constants representing 0 and 1 respectively.)
However, my code is giving me warnings of Type safety: Unchecked cast from ArrayList<capture#1-of ?> to ArrayList<Attribute> (ditto for the other line).
Is there a better approach for what I want to do?
java
java
asked 5 mins ago
user10931326user10931326
1
New contributor
user10931326 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 5 mins ago
user10931326user10931326
1
New contributor
user10931326 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 5 mins ago
user10931326user10931326
1
New contributor
user10931326 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 5 mins ago
user10931326user10931326
1
asked 5 mins ago
user10931326user10931326
1
1
New contributor
user10931326 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
user10931326 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
user10931326 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
add a comment |
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