Java-未捕获异常
这是我创建的例外Java-未捕获异常,java,exception,try-catch,Java,Exception,Try Catch,这是我创建的例外 public class UserNaoExiste extends Exception { public UserNaoExiste(){ super("User não existe"); } } 这就是抛出异常的函数(我相信它实际上是被抛出的) 这就是应该捕获异常的地方 private String login(String username, String password) { Entidades.User u =
public class UserNaoExiste extends Exception {
public UserNaoExiste(){
super("User não existe");
}
}
这就是抛出异常的函数(我相信它实际上是被抛出的)
这就是应该捕获异常的地方
private String login(String username, String password) {
Entidades.User u = null;
String r = "s";
try {
u = udao.getUser(username);
System.out.println("olaola");
} catch (Exception e) {
r = "n";
}
System.out.println(r);
System.out.flush();
if (r.equals("s") && u.checkPassword(password)) {
this.user = u;
this.auth = (u.isAdmin() ? 2 : 1);
} else {
r = "n";
}
return r;
}
实际发生的情况是抛出异常,但很高兴被忽略,println执行,r未设置为“n”,然后它尝试在null上执行u.checkPassword。在我的生活中,我从来没有在编码时如此困惑过。如果在
getUser
方法中得到任何帮助,就会抛出UserNaoExiste
异常,并在同一方法中捕获该异常
try (Connection con = DriverManager.getConnection(this.url, this.username, this.password)) {
PreparedStatement stm = con.prepareStatement("SELECT * FROM user WHERE username = ?");
stm.setString(1, username);
ResultSet rs = stm.executeQuery();
if (rs.next() == false) {
throw new Exceptions.UserNaoExiste();
}
u = new Entidades.User(rs.getString("Username"), rs.getString("Password"), rs.getString("Nick"), rs.getString("Admin"));
} catch (Exception e) {
System.out.println(e.getMessage());
}
在login
方法中,catch语句将永远不会执行,因为getUser
引发的异常已被该getUser
方法捕获
您可以捕获数据库相关异常的特定异常
SQLException
,而不是getUser
方法中的exception
。抛出的异常是在getUser
中捕获的。它永远无法登录到,因为您已经捕获了它。
try (Connection con = DriverManager.getConnection(this.url, this.username, this.password)) {
PreparedStatement stm = con.prepareStatement("SELECT * FROM user WHERE username = ?");
stm.setString(1, username);
ResultSet rs = stm.executeQuery();
if (rs.next() == false) {
throw new Exceptions.UserNaoExiste();
}
u = new Entidades.User(rs.getString("Username"), rs.getString("Password"), rs.getString("Nick"), rs.getString("Admin"));
} catch (Exception e) {
System.out.println(e.getMessage());
}