我的退货声明有问题>.<我想将所有杂志名称存储到
ArrayList<String> ListNameMagazine = new ArrayList<String>();
我有一个数据库;在数据库中有一个表name_magazine
,其中的数据name_magazine
是
杂志1
杂志2
杂志3
杂志4
这是我的主要:
ShowData Show = new ShowData();
int HowManyMagazine = Show.HowManyMagazine(1); // to make sure there is how many Magazine name in my database
//System.out.print(HowManyMagazine); //i want to make sure the data is out.
String nmeMagazine = null; // this variable for get data from return statement
// i want to store in ListNameMagazine
ArrayList<String> ListNameMagazine = new ArrayList<String>();
for (int numbeer = 0;numbeer <= HowManyMagazine ; numbeer++)
{
//Store in 1 variable String, because if arrayList it's error
nmeMagazine = Show.getResult("Select Name_Magazine from Magazine");
// Store again in array list
ListNameMagazine.add(nmeMagazine);
}
for (String s : ListNameMagazine)
{
System.out.println(s); // show the data
}
这是我的回报声明:
public String getResult(String sql)
throws SQLException
{
ResultSet rs = st.executeQuery(sql);
ResultSetMetaData resultsetmetadata = rs.getMetaData();
//String just_try = null;
while (rs.next()) {
System.out.println("Result:"+rs.getString(1));
//just_try = rs.getString(1);
//return just_try;
}
return null; //return just_try;
}
问题出在return语句中。
当注释( // )我擦除并且最后返回 null 时;我删除。它变成了这里:
public String getResult(String sql)
throws SQLException
{
ResultSet rs = st.executeQuery(sql);
ResultSetMetaData resultsetmetadata = rs.getMetaData();
String just_try = null;
while (rs.next()) {
//System.out.println("Result:"+rs.getString(1));
just_try = rs.getString(1);
return just_try;
}
return just_try;
}
当我使用此语句显示数据时。
for (String s : ListNameMagazine)
{
System.out.println(s); // show the data
}
结果只
杂志4
杂志4
杂志4
杂志4
@.@ 我已经搞不清楚@.@ 小姐在哪里了
但是当我在这样的返回语句中显示数据时
public String getResult(String sql)
throws SQLException
{
ResultSet rs = st.executeQuery(sql);
ResultSetMetaData resultsetmetadata = rs.getMetaData();
String just_try = null;
while (rs.next()) {
System.out.println("Result:"+rs.getString(1));
//just_try = rs.getString(1);
//return just_try;
}
return null;
}
数据显示了我想要的。我知道我只是想念某个地方,但我不知道那个@.@ 在哪里。我希望你们能找到它。THX