I am trying to create a connection with a database using JDBC on my android project. I am following a tutorial which says to import a jar and then create a connection in the activity. Everything is ok, but in the connection statement i get an error
Cannot resolve method 'createStatement()'
if I try to get into the reference of the method, it says
cannot find decleration to go to
This method comes from the jar i have imported? (jtds-1.3.1)
Is there anything else i am missing here?
#Override
protected String doInBackground(String... params)
{
Connection con;
String usernam = params[0];
String passwordd = params[1];
if(usernam.trim().equals("")|| passwordd.trim().equals(""))
z = "Please enter Username and Password";
else
{
try
{
con = connectionclass(un, pass, db, ip); // Connect to database
if (con == null)
{
z = "Check Your Internet Access!";
}
else
{
// Change below query according to your own database.
String query = "select * from owner where mail = '" + usernam.toString() + "' and password = '"+ passwordd.toString() +"' ";
Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery(query);
if(rs.next())
{
z = "Login successful";
isSuccess=true;
con.close();
}
else
{
z = "Invalid Credentials!";
isSuccess = false;
}
}
}
catch (Exception ex)
{
isSuccess = false;
z = ex.getMessage();
}
}
return z;
}
}
#SuppressLint("NewApi")
public Connection connectionclass(String user, String password, String database, String server)
{
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
Connection connection = null;
String ConnectionURL = null;
try
{
Class.forName("net.sourceforge.jtds.jdbc.Driver");
ConnectionURL = "jdbc:jtds:sqlserver://" + server + database + ";user=" + user+ ";password=" + password + ";";
connection = (Connection) DriverManager.getConnection(ConnectionURL);
}
catch (SQLException se)
{
Log.e("error here 1 : ", se.getMessage());
}
catch (ClassNotFoundException e)
{
Log.e("error here 2 : ", e.getMessage());
}
catch (Exception e)
{
Log.e("error here 3 : ", e.getMessage());
}
return connection;
}
I got the same problem with the close() method
All you've got to do is specify the class name fully:
java.sql.Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/product","root","");
No need for a cast, and the error you're reporting will now go away, as the compiler will be looking for the method in the right class.
Or just rename your own class Connection.
Related
I am trying connection with database but this error frustrates me . Can anyone help me out what is the problem here?
I want to connect to SQL Server from Eclipse.
public class JDBC_Test {
public static void SQLServerConnection() {
try {
String url = "jdbc:sqlserver://localhost:1433;DatabaseName=Northwind";
String user = "sa";
String password = "832Waseem#";
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
Connection con = DriverManager.getConnection(url, user, password);
System.out.println("Connection Created Successfully.......");
Statement st = con.createStatement();
ResultSet rs = st.executeQuery("select * from categories");
while (rs.next()) {
System.out.println(rs.getInt(1) + " " + rs.getString(2) + " " + rs.getString(3));
}
con.close();
System.out.println("Connection Closed Successfully.......");
} catch (Exception e) {
// System.out.println("Unable to create Connection reason is as below.......");
e.printStackTrace();
}
}
public static void main(String args[]) {
SQLServerConnection();
}
}
My Error:
com.microsoft.sqlserver.jdbc.SQLServerException: Login failed for user 'sa'. at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDatabaseError(SQLServerException.java:196)
I have imported the JDBC library, set it to be compiled, and gave the App permission to access Internet.
When a button on Screen is pressed, it should connect to the database and give me the values to implement in the list.
When I press the button, I can see it giving me the "Connecting to database" text, but after about half a second it says "Exception" as defined in that last catch block.
I commented out the three lines of code in onPostExecute, because when I kept them the App would just crash.
public void retrieveData(View view) {
GetData retrieveData = new GetData();
retrieveData.execute();
}
private class GetData extends AsyncTask<String,String,String> {
String msg = "";
static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";
static final String DB_URL = "jdbc:mysql://" + DbStrings.DATABASE_URL + "/" + DbStrings.DATABASE_NAME;
#Override
protected void onPreExecute() {
progress.setText("Connecting to database");
}
#Override
protected String doInBackground(String... strings) {
Connection conn = null;
Statement stmt = null;
try {
Class.forName(JDBC_DRIVER);
conn = DriverManager.getConnection(DB_URL, DbStrings.USERNAME, DbStrings.PASSWORD);
stmt = conn.createStatement();
String sql = "SELECT * FROM video"; //
ResultSet rs = stmt.executeQuery(sql);
while(rs.next()) {
String name = rs.getString("title");
buildNames += name + " ### ";
}
msg = "Process complete.";
rs.close();
conn.close();
stmt.close();
} catch(SQLException connError) {
msg = "An exception was thrown for JDBC.";
connError.printStackTrace();
} catch (ClassNotFoundException e) {
msg = "A Class not found exception was thrown.";
e.printStackTrace();
} catch (java.sql.SQLException e) {
msg = "Exception";
e.printStackTrace();
} finally {
try{
if(stmt != null) {
stmt.close();
}
} catch (java.sql.SQLException e) {
e.printStackTrace();
}
try{
if(conn != null) {
conn.close();
}
} catch (java.sql.SQLException e) {
e.printStackTrace();
}
}
return null;
}
#Override
protected void onPostExecute(String msg) {
progress.setText(this.msg);
//names = buildNames.substring(0,buildNames.length()-5).split(" ### ");
//itemAdapter = new ItemAdapter(thisContext, buildNames.substring(0,buildNames.length()-5).split(" ### ")); //crashes
//namesList.setAdapter(itemAdapter);
}
}
}
After checking the stack trace I found this:
java.sql.SQLException: Unknown initial character set index '192' received from server.
And so I knew what to search for;
I was using an outdated version of JDBC, (3.x). After importing Version 5.1.46, it is now working :).
I had developed an android app to connect with MS-sql database it is connected but it does not get correct result it gives
net.sourceforge.jtds.jdbc.jtdsresultset#1245
as result for select itemname from oitm where itemcode='dcs1515'
Please help me to solve this issue. I am using android studio-3.1.0 and ms-sql 2008. I connected android with db using jtds-1.3.1.jar for jdbc connection
class Disp extends AsyncTask<String, String, String> {
#Override
protected void onPostExecute(String s) {
Toast.makeText(MainActivity.this, s, Toast.LENGTH_LONG).show();
}
#Override
protected String doInBackground(String... strings) {
connect con = new connect();
String k=null;
ct = con.connectionclass();
if (ct == null){
k="Check Internet";
}
else{
try {
String st = "select itemname from oitm where itemcode='dcs1515'";
Statement smt = ct.createStatement();
ResultSet resultSet = smt.executeQuery(st);
if(resultSet.next())
{
k = resultSet.toString();//"success ";//+resultSet+" deleted";
}
} catch (SQLException e) {
k=e.getMessage();
}
}
return k;
}
}
}
connection class is
public class connect {
String ip = "192.167.0.7";
String db = "RCCLive";
String un = "artika";
String pass = "Acm#157";
public Connection connectionclass()
{
{
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
Connection connection = null;
String ConnectionURL = null;
try
{
Class.forName("net.sourceforge.jtds.jdbc.Driver");
ConnectionURL = "jdbc:jtds:sqlserver://" + ip + ";" + db + ";user=" + un+ ";password=" + pass + ";";
connection = DriverManager.getConnection(ConnectionURL);
}
catch (SQLException se)
{
Log.e("error here 1 : ", se.getMessage());
}
catch (ClassNotFoundException e)
{
Log.e("error here 2 : ", e.getMessage());
}
catch (Exception e)
{
Log.e("error here 3 : ", e.getMessage());
}
return connection;
}
}
}
k = resultSet.toString();
This should be
k = resultSet.getString(1);
You cannot just take the String value of the ResultSet, you must retrieve the first column of the ResultSet, which is what getString(1) does.
I'm trying to implement a (more) robust application using Threads.
My JdbcAccess.java more relevant part is:
protected ResultSet readfromSQLServer(String url, String instance, String port, String database, String user, String passwd, String query) throws Exception {
try {
// This will load the SQLServer driver
Class.forName("net.sourceforge.jtds.jdbc.Driver");
// Setup the connection with the DB
String connectionUrl = "";
if (instance != null || instance == "") {
connectionUrl = "jdbc:jtds:sqlserver://" + url + ":" + port + "/" + database + ";instance=" + instance + ";user=" + user + ";password=" + passwd;
} else {
connectionUrl = "jdbc:jtds:sqlserver://" + url + ":" + port + "/" + database + ";user=" + user + ";password=" + passwd;
}
start();
connection = DriverManager.getConnection(connectionUrl);
// Statements allow to issue SQL queries to the database
statement = (Statement) connection.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE);
resultSet = statement.executeQuery(query);
} catch (Exception e) {
e.printStackTrace();
}
return resultSet;
}
public void run() {
System.out.println("Running JdbcAccess thread");
try {
// Let the thread sleep for a while.
Thread.sleep(50);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public void start () {
System.out.println("Starting JdbcAccess thread");
if (thread == null) {
thread = new Thread (this);
thread.start ();
}
}
Problem is that if it has a flawed SQL query the whole application crashes instead of the intended result of just the thread failing / dying out.
What am I doing wrong here?
This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 7 years ago.
I get error on
java.lang.NullPointerException: Attempt to invoke interface method
'java.sql.Statement java.sql.Connection.createStatement()' on a null
object reference at
com.example.jacquesarroyo.onlinelibrary.suggestions$3.onClick(suggestions.java:81)
Here's the code I used:
add = (Button) findViewById(R.id.btnadd);
errorlbl = (TextView) findViewById(R.id.lblerror);
title = (EditText) findViewById(R.id.txttitle);
author = (EditText) findViewById(R.id.txtauthor);
year = (EditText) findViewById(R.id.txtyear);
location = (EditText) findViewById(R.id.txtlocation);
ipaddress = "10.0.0.5";
db = "SampleDatabase";
username = "admin"
password = "admin";
connect = ConnectionHelper(username, password, db, ipaddress);
add.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
try {
st = connect.createStatement();
preparedStatement = connect
.prepareStatement("Insert into Books(Title,Author,Year) values ('"
+ title.getText().toString()
+ "','"
+ author.getText().toString()
+ "','"
+ year.getText().toString() + "')");
preparedStatement.executeUpdate();
errorlbl.setText("Data Added successfully");
} catch (SQLException e) {
errorlbl.setText(e.getMessage().toString());
}
}
});
#SuppressLint("NewApi")
private Connection ConnectionHelper(String user, String password,
String database, String server) {
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder()
.permitAll().build();
StrictMode.setThreadPolicy(policy);
Connection connection = null;
String ConnectionURL = null;
try {
Class.forName("net.sourceforge.jtds.jdbc.Driver");
ConnectionURL = "jdbc:jtds:sqlserver://" + server + ";"
+ "databaseName=" + database + ";user=" + user
+ ";password=" + password + ";" + "ssl=false";
connection = DriverManager.getConnection(ConnectionURL);
} catch (SQLException se) {
Log.e("ERROR", se.getMessage());
} catch (ClassNotFoundException e) {
Log.e("ERROR", e.getMessage());
} catch (Exception e) {
Log.e("ERROR", e.getMessage());
}
return connection;
}
line 81 is: st = connect.createStatement();
NullPointerException means that the variable you are trying to use is not initialized or is null.
Before calling:
connect.createStatement();
you have to initialize the connect object first by:
Connection connect = ConnectionHelper(user,password,database,server);
Keep in mind scope of the variables.