我的錯誤代碼:
Exception in thread "main" java.lang.NullPointerException
at lesebank.Konto.getKontofromID(Konto.java:39)
at lesebank.Main.main(Main.java:18)
SQL EXCEPTIONJava Result: 1
BUILD SUCCESSFUL (total time: 1 second)
方法:
Konto konto = new Konto();
Statement s = dbconn.getSt();
try
{ //in the next line the error occurs
s.execute("select id,inhaberin,ktostd,habenzinsen,notiz from Konto where id = " +id);
ResultSet set = s.getResultSet();
if (set.next())
{
konto.setId(set.getInt(1));
konto.setId_inhaberin(set.getInt(2));
konto.setKtostd(set.getDouble(3));
konto.setHabenzinsen(set.getDouble(4));
konto.setNotiz(set.getString(5));
return konto;
}
}
catch (SQLException ex)
{
System.out.print(ex.getMessage());
}
return null;
DBConn:
public class DBConnection {
private String url = "jdbc:derby://localhost:1527/Bank";
private Connection conn;
private Statement st;
public DBConnection() {
try
{
conn = DriverManager.getConnection(this.url, "test", "test");
st = conn.createStatement();
}
catch (SQLException ex)
{
System.out.print("SQL EXCEPTION");
}
}
public Statement getSt() {
return st;
}
數據庫:
請幫助
你能指出哪一行是第39行嗎?所以我們可以確切地知道哪一行會引發異常。 – 2011-03-14 20:33:05
固定............. – user547995 2011-03-14 20:37:43
什麼是dbconn? – skaffman 2011-03-14 20:38:08