NullPointerException when attempting to login JSF Web Application - jsf

Question

first time poster so apologies for any mistakes. I have a web application connected to an Oracle database and don't understand why I am getting the NPE when trying to login:
StackTrace:
It points to this method in my login bean:
public String checkCredentials() {
String outcome = "";
User user = userHandler.findUserByUsername(username); <---NullPointerException
if (username.equals(user.getUserName())
&& password.equals(user.getPassword())) {
//clearFields();
switch (user.getUserType()) {
case "Super":
outcome = "Super";
break;
case "Admin":
outcome = "Admin";
break;
case "Teacher":
outcome = "Teacher";
break;
case "Parent":
outcome = "Parent";
break;
case "Student":
outcome = "Student";
break;
}
}
if (outcome.isEmpty()) {
clearFields();
FacesMessage msg = new FacesMessage("Username and/or password not recognised.");
FacesContext.getCurrentInstance().addMessage(null, msg);
}
return outcome;
}
I have tested the following method in the handler to ensure the SQL pulls the correct info:
public User findUserByUsername(String username) {
User u = null;
DatabaseConnection con = ConnectionManager.getInstance().getConnection();
con.prepareStatement(FIND_USER_BY_USERNAME);
con.setStatementParameter(1, username);
if (con.executePreparedStatement()) {
u = prepareUser(con.getResultSet());
}
con.close();
return u;
}
private User prepareUser(ResultSet rs) {
User u = null;
try {
if (rs.next()) {
u = new User(rs.getInt("UserId"),
rs.getString("fName"),
rs.getString("lName"),
rs.getString("userName"),
rs.getString("password"),
rs.getString("userType"),
rs.getInt("schoolID"));
}
} catch (SQLException sqle) {
sqle.getMessage();
}
return u;
}
Here is my login xhtml:
<h:body>
<ui:composition template="/template.xhtml">
<ui:define name="content">
<h2>Login</h2>
<h:messages class="error" />
<h:form>
<p>Username:
<h:inputText id="username"
maxlength="12"
required="true"
requiredMessage="Please enter your username"
title="Your username: "
value="#{login.username}" />
</p>
<p>Password:
<h:inputSecret id="password"
maxlength="15"
required="true"
requiredMessage="Please enter your password"
title="Your password: "
value="#{login.password}" />
</p>
<p>
<h:commandButton type="submit" value="Log-in" action="#{login.checkCredentials()}"/>
<h:commandButton type="reset" value="Reset" />
</p>
</h:form>
</ui:define>
</ui:composition>
</h:body>
The username that is used where the NPE points is set by the user in the form, the username and password exist in my database and the SQL string 'FIND_USER_BY_USERNAME' pulls the correct user when tested separate. Would really appreciate a point in the right direction.
edit:
Login_UI:
package Beans;
import ActiveRecord.User;
import ActiveRecord.UserHandler;
import java.io.Serializable;
import javax.inject.Named;
import javax.enterprise.context.SessionScoped;
import javax.faces.application.FacesMessage;
import javax.faces.context.FacesContext;
#Named(value = "login")
#SessionScoped
public class Login_UI implements Serializable {
private String username;
private String password;
private String userType;
private final transient UserHandler userHandler;
public Login_UI() {
clearFields();
userHandler = new UserHandler();
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getUserType() {
return userType;
}
public void setUserType(String userType) {
this.userType = userType;
}
public void clearFields() {
username = "";
password = "";
}
public String checkCredentials() {
String outcome = "";
User user = userHandler.findUserByUsername(username);
if (username.equals(user.getUserName())
&& password.equals(user.getPassword())) {
//clearFields();
switch (user.getUserType()) {
case "Super":
outcome = "Super";
break;
case "Admin":
outcome = "Admin";
break;
case "Teacher":
outcome = "Teacher";
break;
case "Parent":
outcome = "Parent";
break;
case "Student":
outcome = "Student";
break;
}
}
if (outcome.isEmpty()) {
clearFields();
FacesMessage msg = new FacesMessage("Username and/or password not recognised.");
FacesContext.getCurrentInstance().addMessage(null, msg);
}
return outcome;
}
}
userHandler:
package ActiveRecord;
import Database.ConnectionManager;
import Database.DatabaseConnection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
public class UserHandler {
private static final String FIND_USER_BY_USERNAME = "SELECT userID, fName, lName, "
+ "username, password, usertype, FK1_schoolID FROM UserInformation "
+ "WHERE UserName = ?";
private static final String FIND_USER_BY_ID = "SELECT fName, lName, userName, "
+ "password, userType, FK1_schoolID FROM UserInformation "
+ "WHERE userID = ?";
private static final String FIND_USER_BY_FNAME = "SELECT * FROM UserInformation "
+ "WHERE fName = ? "
+ "ORDER BY userID";
private static final String FIND_USER_BY_LNAME = "SELECT * FROM UserInformation "
+ "WHERE lName = ? "
+ "ORDER BY userID";
private static final String FIND_ALL_USERS = "SELECT * FROM UserInformation "
+ "ORDER BY userID";
private static final String FIND_STUDENT_BY_ID = "SELECT StudentID, yearGroup, "
+ "overallMarks, FK2_UserID FROM Student WHERE StudentID = ? ";
private static final String FIND_STUDENT_BY_YEARGROUP = "SELECT StudentID, yearGroup, "
+ "overallMarks, FK2_UserID FROM Student WHERE yearGroup = ? "
+ "ORDER BY studentID";
private static final String FIND_ALL_STUDENTS = "SELECT * FROM Student "
+ "LEFT JOIN UserInformation ON Student.FK2_UserId = UserInformation.UserId "
+ "ORDER BY Student.studentId";
private User prepareUser(ResultSet rs) {
User u = null;
try {
if (rs.next()) {
u = new User(rs.getInt("UserId"),
rs.getString("fName"),
rs.getString("lName"),
rs.getString("userName"),
rs.getString("password"),
rs.getString("userType"),
rs.getInt("schoolID"));
System.out.println("Test: prepUser");
}
} catch (SQLException sqle) {
sqle.getMessage();
}
return u;
}
private ArrayList<User> prepareUsers(ResultSet rs) {
ArrayList<User> u = new ArrayList();
try {
while (rs.next()) {
u.add(new User(rs.getInt("UserId"),
rs.getString("fName"),
rs.getString("lName"),
rs.getString("userName"),
rs.getString("password"),
rs.getString("userType"),
rs.getInt("schoolID")));
}
} catch (SQLException sqle) {
sqle.getMessage();
}
return u;
}
private Student prepareStudent(ResultSet rs) {
Student s = null;
try {
if (rs.next()) {
s = new Student(rs.getInt("StudentId"),
rs.getInt("yearGroup"),
rs.getInt("overallMarks"),
rs.getInt("FK1_StudenttestID"),
rs.getInt("FK2_UserID"));
}
} catch (SQLException sqle) {
sqle.getMessage();
}
return s;
}
private ArrayList<Student> prepareStudents(ResultSet rs) {
ArrayList<Student> s = new ArrayList();
try {
while (rs.next()) {
s.add(new Student(rs.getInt("StudentId"),
rs.getInt("yearGroup"),
rs.getInt("overallMarks"),
rs.getInt("FK1_StudenttestID"),
rs.getInt("FK2_UserID")));
}
} catch (SQLException sqle) {
sqle.getMessage();
}
return s;
}
public User findUserById(int userId) {
User u = null;
DatabaseConnection con = ConnectionManager.getInstance().getConnection();
con.prepareStatement(FIND_USER_BY_ID);
con.setStatementParameter(1, userId);
if (con.executePreparedStatement()) {
u = prepareUser(con.getResultSet());
}
con.close();
return u;
}
public ArrayList<User> findUserByFirstName(String fName) {
ArrayList<User> u = null;
DatabaseConnection con = ConnectionManager.getInstance().getConnection();
con.prepareStatement(FIND_USER_BY_FNAME);
con.setStatementParameter(1, fName);
if (con.executePreparedStatement()) {
u = prepareUsers(con.getResultSet());
}
con.close();
return u;
}
public ArrayList<User> findUserByLastName(String lName) {
ArrayList<User> u = null;
DatabaseConnection con = ConnectionManager.getInstance().getConnection();
con.prepareStatement(FIND_USER_BY_LNAME);
con.setStatementParameter(1, lName);
if (con.executePreparedStatement()) {
u = prepareUsers(con.getResultSet());
}
con.close();
return u;
}
public User findUserByUsername(String username) {
User u = null;
DatabaseConnection con = ConnectionManager.getInstance().getConnection();
con.prepareStatement(FIND_USER_BY_USERNAME);
con.setStatementParameter(1, username);
if (con.executePreparedStatement()) {
u = prepareUser(con.getResultSet());
}
con.close();
return u;
}
public ArrayList<User> findAllUsers() {
ArrayList<User> u = null;
DatabaseConnection con = ConnectionManager.getInstance().getConnection();
con.prepareStatement(FIND_ALL_USERS);
if (con.executePreparedStatement()) {
u = prepareUsers(con.getResultSet());
}
con.close();
return u;
}
public Student findStudentById(int studentId) {
Student s = null;
DatabaseConnection con = ConnectionManager.getInstance().getConnection();
con.prepareStatement(FIND_STUDENT_BY_ID);
con.setStatementParameter(1, studentId);
if (con.executePreparedStatement()) {
s = prepareStudent(con.getResultSet());
}
con.close();
return s;
}
public ArrayList<Student> findStudentByYearGroup() {
ArrayList<Student> s = null;
DatabaseConnection con = ConnectionManager.getInstance().getConnection();
con.prepareStatement(FIND_STUDENT_BY_YEARGROUP);
if (con.executePreparedStatement()) {
s = prepareStudents(con.getResultSet());
}
con.close();
return s;
}
public ArrayList<Student> findAllStudents() {
ArrayList<Student> s = null;
DatabaseConnection con = ConnectionManager.getInstance().getConnection();
con.prepareStatement(FIND_ALL_STUDENTS);
if (con.executePreparedStatement()) {
s = prepareStudents(con.getResultSet());
}
con.close();
return s;
}
public boolean createUser(User u) {
boolean userCreated = false;
ArrayList<User> users = findAllUsers();
boolean found = false;
for (User x : users) {
if (x.getUserName().equals(u.getUserName())) {
found = true;
}
}
if (!found) {
try {
u.insert();
userCreated = true;
} catch (Exception e) {
e.getMessage();
}
}
return userCreated;
}
public boolean deleteUser(User u) {
boolean deleted = false;
if (u != null) {
try {
u.delete();
deleted = true;
} catch (Exception e) {
e.getMessage();
}
}
return deleted;
}
}
Apologies for all the edits, I have found the problem just not sure how to fix it, my singleton database connection should create a pool of 5 available connections DatabaseConnection con = ConnectionManager.getInstance().getConnection(); but during this call it returns a null connection
package Database;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
public class DatabaseConnection {
private static final String DATABASE_URL = "removed";
private final ConnectionManager connManager;
private Connection conn = null;
private PreparedStatement stmt = null;
private ResultSet rs = null;
private int updateCount = -1;
public DatabaseConnection(ConnectionManager connectionManager) throws SQLException {
connManager = connectionManager;
DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
conn = DriverManager.getConnection(DATABASE_URL);
}
public void close() {
connManager.releaseConnection(this);
}
public boolean prepareStatement(String sql) {
boolean statementPrepared = false;
try {
stmt = conn.prepareStatement(sql);
statementPrepared = true;
} catch (SQLException sqle) {
sqle.getMessage();
}
return statementPrepared;
}
public boolean executePreparedStatement() {
boolean resultSetAvailable = false;
try {
resultSetAvailable = stmt.execute();
updateCount = stmt.getUpdateCount();
rs = stmt.getResultSet();
} catch (SQLException sqle) {
sqle.getMessage();
}
return resultSetAvailable;
}
public boolean setStatementParameter(int paramIndex, boolean paramValue) {
boolean paramSet = false;
if (stmt != null) {
try {
stmt.setBoolean(paramIndex, paramValue);
paramSet = true;
} catch (SQLException sqle) {
sqle.getMessage();
}
}
return paramSet;
}
public boolean setStatementParameter(int paramIndex, String paramValue) {
boolean paramSet = false;
if (stmt != null) {
try {
stmt.setString(paramIndex, paramValue);
paramSet = true;
} catch (SQLException sqle) {
sqle.getMessage();
}
}
return paramSet;
}
public boolean setStatementParameter(int paramIndex, int paramValue) {
boolean paramSet = false;
if (stmt != null) {
try {
stmt.setInt(paramIndex, paramValue);
paramSet = true;
} catch (SQLException sqle) {
sqle.getMessage();
}
}
return paramSet;
}
public int getUpdateCount() {
return updateCount;
}
public ResultSet getResultSet() {
return rs;
}
}
package Database;
import java.sql.SQLException;
import java.util.ArrayList;
public class ConnectionManager {
private static final ConnectionManager instance = new ConnectionManager();
private final ArrayList<DatabaseConnection> available;
private final ArrayList<DatabaseConnection> busy;
private ConnectionManager() {
available = new ArrayList();
busy = new ArrayList();
for (int i = 0; i < 5; i++) {
try {
available.add(new DatabaseConnection(this));
} catch (SQLException sqle) {
sqle.getMessage();
}
}
}
public static ConnectionManager getInstance() {
return instance;
}
public DatabaseConnection getConnection() {
DatabaseConnection connection = null;
synchronized (this) {
if (!available.isEmpty()) {
connection = available.remove(0); <---This gets skipped over as available is never added to
busy.add(connection);
}
}
return connection;
}
public void releaseConnection(DatabaseConnection connection) {
if (connection != null) {
synchronized (this) {
if (busy.remove(connection)) {
available.add(connection);
}
}
}
}
}

Answer 1

It seems that the error lies somewhere with your custom built connection pool. While it is tempting to create one yourself, it's not very simple because it can easily mess up the API, the transaction management, the pool auto-sizing when more connections than expected are needed. I would suggest that you use one of the libraries that are already there, and do the job perfectly, such as C3PO. After that, your ConnectionPool/CollectionManager singleton can be as simple as this:
public class ConnectionPool {
private static ComboPooledDataSource cpds;
private static class ConnectionPoolHolder {
private static final ConnectionPool INSTANCE = new ConnectionPool();
}
private ConnectionPool() {
cpds = new ComboPooledDataSource();
try {
cpds.setDriverClass(ServerConfig.JDBC_DRIVER_CLASS); //loads the jdbc driver
} catch (PropertyVetoException e) {
e.printStackTrace();
}
cpds.setJdbcUrl(ServerConfig.CONNECTION_STRING);
cpds.setUser(ServerConfig.DB_USER);
cpds.setPassword(ServerConfig.DB_PASS);
// the settings below are optional -- c3p0 can work with defaults
cpds.setMinPoolSize(ServerConfig.MIN_POOL_SIZE);
cpds.setAcquireIncrement(5);
cpds.setMaxPoolSize(ServerConfig.MAX_POOL_SIZE);
cpds.setTestConnectionOnCheckin(true);
cpds.setPreferredTestQuery("select 1");
cpds.setTestConnectionOnCheckout(true);
cpds.setIdleConnectionTestPeriod(9000);
}
public static ConnectionPool getInstance() {
return ConnectionPoolHolder.INSTANCE;
}
public Connection getConnection() {
try {
return cpds.getConnection();
} catch (SQLException e) {
e.printStackTrace();
}
return null;
}
}