simone giusti

Suppose you have an activity who manage a socket connection (to a telnet server).

MainActivity opens connection to server.
Once this connection is active I can send commands from mainactivity.

Now I need to send a command to that connection from other activity. This connection is not static.

How can I do that ??


Thanks.

Yes .. maybe you are right but since method works from main I thought it worked from other class
How can I assign ?

Rob Spoor wrote:And where do you assign anything to your telnetClient? Because my guess is that you don't, which means the reference remains null.

This is method in mainactivity:

public void Hkcount() {        String HKcount = (telnetClient.command("/_info/hkeycount"));        Log.e("HKcount", HKcount);    }

This method reports no errors if called from inside MainActivity.

Thanks.

Rob Spoor wrote:

simone giusti wrote:This is the error:

Attempt to invoke virtual method 'java.lang.String it.rockopera.scsremote.TelnetClient.command(java.lang.String)' on a null object reference

The error is actually pretty clear. Somewhere (not in the code you've shown) you have a reference to a TelnetClient on which you call command. However, that reference is null.

Can you show the piece of code where you call this command method?

MainActivity established a socket connection. I have a method in MainActivity which sends commands to this connection.
How can invoke this method from another class ???

This is the error:

Attempt to invoke virtual method 'java.lang.String it.rockopera.scsremote.TelnetClient.command(java.lang.String)' on a null object reference

This is method whick invoke MainActivity's method
   public void RunHkCount() {                mainActivity = new MainActivity();                      mainActivity.Hkcount();        }

This method could not be static.

Thanks

Tim Moores wrote:Not knowing the IP address would be very unusual. Something like Bonjour might make that possible, but Telnet has really fallen out of favor due to its unsecured nature. Mind telling us a bit about the use case?

I am programming a java app to remotely control a desktop software.
This software acts a server and my app is the client.
At the moment, I manually insert IP and port in app’s settings.
It would be better that app could find automatically these informations looking for software's inside server.
Would you help me suggesting a way to do that ??

Many thanks in advance.

Hello,
is there a way to auto-find a telnet server on a network ??

Suppose there is a server waiting on a port on a unknown IP address ...

I would like my app to explore network obtaing ip and port of this server, without having to set it manually.


thanks !

Suppose you have this class:

package it.rockopera.scsremote; import android.content.Context; import java.util.Timer; import java.util.TimerTask;        public class CueTimer extends Thread{        private Context context;        private MainActivity main = new MainActivity();        private Timer timer;        int elapsed = 0 ;          public CueTimer(Context c)        {            context= c;            timer = new Timer();            timer.schedule(new TimerTask() {                @Override                public void run() {                    elapsed+=1000;                    System.out.println("elapsed: " + String.valueOf(elapsed));                                  }            },0,1000);//Update text every second        }


I would like to call this method from another class in this way:

CueTimer cuetimer = new CueTimer(context);                            cuetimer.start()



here's the error:
Process: it.rockopera.scsremote, PID: 7562                                                                      java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()                                                                          at android.os.Handler.<init>(Handler.java:200)                                                                          at android.os.Handler.<init>(Handler.java:114)                                                                          at android.app.Activity.<init>(Activity.java:789)                                                                          at it.rockopera.scsremote.MainActivity.<init>(MainActivity.java:47)                                                                          at it.rockopera.scsremote.CueTimer.<init>(CueTimer.java:32)                                                                          at it.rockopera.scsremote.Client$Read_SCS_MSGs.run(Client.java:477)                                                                          at java.lang.Thread.run(Thread.java:761)

Thanks !!

Too easy or too difficult?

simone giusti wrote:Suppose a simple method in MainActivity:

public void TEST(){    Log.e("TEST", "TEST"); }

I would like to call it from another class:

MainActivity main = new MainActivity();                            main.TEST();


This is the result:
java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()


Will you help me ???

Thanks.

Suppose a simple method in MainActivity:

public void TEST(){    Log.e("TEST", "TEST"); }

I would like to call it from another class:

MainActivity main = new MainActivity();                            main.TEST();


This is the result:
java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()


Will you help me ???

Thanks.

Hello,
I have a simple listview binded to db values.

From MainActivity how can I change value to a textview inside each row of the listview ??

Yes, this is the case.

How can I verify that condition ??

Is it what you mean?
while (running) {    if (condition is met AND method didn't execute in the past second or two) {        execute method    } }

Hello I would like to run a method when a condition occurs.
Since it may happen more than one time I would like to fire method not more than once every 1 o 2 seconds ...

How can I do that ??

Thanks.

Ron McLeod wrote:One problem is the you are calling your update method on a new instance of MainActivity, rather than the launched MainActivity instance:MainActivity main = new MainActivity(); main.UPDLV();

Thank Ron ... helpful !!

Now this is the error:

12-31 22:09:20.003 5818-5818/it.rockopera.scsremote W/System.err: java.lang.NullPointerException: Attempt to invoke virtual method 'android.database.Cursor it.rockopera.scsremote.DBLayer.Execute(java.lang.String, it.rockopera.scsremote.DBLayer$TipoQuery)' on a null object reference 12-31 22:09:20.003 5818-5818/it.rockopera.scsremote W/System.err:     at it.rockopera.scsremote.MainActivity.UpdateLV(MainActivity.java:1509) 12-31 22:09:20.003 5818-5818/it.rockopera.scsremote W/System.err:     at it.rockopera.scsremote.DBLayer$PostTask.onPostExecute(DBLayer.java:214) 12-31 22:09:20.003 5818-5818/it.rockopera.scsremote W/System.err:     at it.rockopera.scsremote.DBLayer$PostTask.onPostExecute(DBLayer.java:187) 12-31 22:09:20.003 5818-5818/it.rockopera.scsremote W/System.err:     at android.os.AsyncTask.finish(AsyncTask.java:660) 12-31 22:09:20.003 5818-5818/it.rockopera.scsremote W/System.err:     at android.os.AsyncTask.-wrap1(AsyncTask.java) 12-31 22:09:20.003 5818-5818/it.rockopera.scsremote W/System.err:     at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:677) 12-31 22:09:20.003 5818-5818/it.rockopera.scsremote W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:102) 12-31 22:09:20.003 5818-5818/it.rockopera.scsremote W/System.err:     at android.os.Looper.loop(Looper.java:154) 12-31 22:09:20.003 5818-5818/it.rockopera.scsremote W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:6077) 12-31 22:09:20.003 5818-5818/it.rockopera.scsremote W/System.err:     at java.lang.reflect.Method.invoke(Native Method) 12-31 22:09:20.003 5818-5818/it.rockopera.scsremote W/System.err:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865) 12-31 22:09:20.003 5818-5818/it.rockopera.scsremote W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)


here is complete mainactivity code:
public class MainActivity extends Activity {    Context context;    ArrayList<DataModel> dataModels;    public static ListView CuesLV;    public  CustomAdapter adapter;    private SeekBar VolumeBar;    private View MapCover;    public DBLayer db = null;    @Override    protected void onDestroy() {        super.onDestroy();        Log.e("DB: ", "onDESTROY");        db.close();    }    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        context=this;        CuesLV =(ListView)findViewById(R.id.listP);                            FillDB();                           UpdateLV();                        }                    });    public void FillDB() {            System.out.println("Start FillDB");            try{                Log.e("num rec before del: ", String.valueOf(db.CountRecords()));                db.deleteAll();   // delete CUES on table               Log.e("num rec after del: ", String.valueOf(db.CountRecords()));                int cueTotNumber  =  Integer.parseInt(c.TelnetCMD1("/_info/finalcue").replace("/_info/finalcue ", ""));                 int[] cue_idx = new int[cueTotNumber];                 String[] cue_label = new String[cueTotNumber];                 String[] cue_name = new String[cueTotNumber];                 int[] cue_len = new int[cueTotNumber];                String[] cue_type=new String[cueTotNumber];                int[] cue_state = new int[cueTotNumber];                String[] cue_colB = new String[cueTotNumber];                String[] cue_colF = new String[cueTotNumber];                String[] cue_colTEMP = new String[cueTotNumber];                TextView Proj_label = (TextView) findViewById(R.id.proj_textview);                Proj_label.setText(((c.TelnetCMD1("/_prod/gettitle")).replace("/_prod/gettitle","")).replace("\"",""));                for(int i= 0 ; i < (cueTotNumber); i++){                    Log.e(String.valueOf(i), "");                    cue_idx[i]=i + 1;                    cue_label[i]=(c.TelnetCMD1("/_info/getcue " + (i+1)).replace("/_info/getcue " + (i+1) + " ", "").replace("\"",""));                    cue_name[i]=((c.TelnetCMD1("/_cue/getname " + cue_label[i]).replace("/_cue/getname \"" + cue_label[i] + "\" ", "").replace("\"",""))).replace("\'","");                    cue_len[i]= Integer.parseInt((c.TelnetCMD1("/_cue/getlength " + cue_label[i]).replace("/_cue/getlength " + "\"" + cue_label[i] + "\"" + " ", "")));                    cue_state[i]=Integer.parseInt((c.TelnetCMD1("/_cue/getstate " + cue_label[i]).replace("/_cue/getstate " + "\"" + cue_label[i] + "\"" + " ", "")));                    cue_colB[i]="#b3e4ff";                    cue_colF[i]="#0f2e5b";                    cue_type[i]=((c.TelnetCMD1("/_cue/gettype " + cue_label[i]).replace("/_cue/gettype \"" + cue_label[i] + "\" ", "").replace("\"",""))).replace("\'","");                    cue_colTEMP[i]=((c.TelnetCMD1("/_cue/getcolors " + cue_label[i]).replace("/_cue/getcolors \"" + cue_label[i] + "\" ", "")).replace("\"",""));                    cue_colB[i]=cue_colTEMP[i].substring(0,7);                    cue_colF[i]=cue_colTEMP[i].substring(8,16);                    String strQuery = "INSERT INTO Cues_table (CueNUM, CueLABEL, CueNAME, CueLEN, CuePOS, CueType, CueSTATE, CueColB, CueColF) VALUES ";                    strQuery += "("+ cue_idx[i] + ",'" +  cue_label[i] + "','" + cue_name[i] + "'," + cue_len[i] + "," + 0 + ",'" +  cue_type[i] + "'," + cue_state[i] +",'" + cue_colB[i] + "','" + cue_colF[i] + "')";                    Log.i("query",strQuery);                    db.Execute(strQuery, DBLayer.TipoQuery.Comando);                }                Log.e("num records 3: ", String.valueOf(db.CountRecords()));            }            catch (Exception e){                Log.i("Errore","qualcosa non va");                System.out.println("Got an IOException: " + e.getMessage());            }        }    public void UpdateLV(){ // prima creazione LV            try{                String strQuery = "SELECT CueLABEL, CueNAME, CueColB, CueColF, CueTYPE, CueSTATE FROM Cues_table";                Cursor c = db.Execute(strQuery, DBLayer.TipoQuery.Selezione);                if (c != null){                    for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){                        //Log.e("c.GETSTRING STATE", c.getString(5));                        dataModels.add(new DataModel(c.getString(0), c.getString(1), c.getString(2), c.getString(3), c.getString(4), c.getInt(5)));                    }                }                Log.e("prima di" , " NOTIFY");                CuesLV.setAdapter(adapter);              //  adapter.notifyDataSetChanged();               Log.e("dopo di" , " UpdateLV"); */            }catch (SQLException se){        System.out.println("Got an IOException: " + se.getMessage());    }    catch(Exception e){        //Handle errors for Class.forName        e.printStackTrace();        }    }


and this is DBlayer:

package it.rockopera.scsremote; import android.content.Context; import android.database.Cursor; import android.database.SQLException; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteOpenHelper; import android.os.AsyncTask; import android.os.Looper; import android.os.Message; import android.util.Log; import android.widget.ListView; import java.util.ArrayList; import java.util.HashMap; import android.os.Handler; import org.antlr.v4.codegen.model.LL1AltBlock; import static it.rockopera.scsremote.MainActivity.CuesLV; public class DBLayer  {   // private Context context;    public static enum TipoQuery {        Selezione,        Comando    }    public static final String DATABASE_NAME = "scsDB";    public static final int DATABASE_VERSION = 1;    ArrayList<DataModel> dataModels;    ListView listView;    private static CustomAdapter adapter;    private DbHelper ourHelper;    private  static Context ourContext;    private static SQLiteDatabase ourDatabase;    private static class DbHelper extends SQLiteOpenHelper {        public DbHelper(Context context) {            super(context, DATABASE_NAME, null, DATABASE_VERSION);            // TODO Auto-generated constructor stub        }        @Override        public void onCreate(SQLiteDatabase db) {            db.execSQL("CREATE TABLE 'Cues_table' ('CueNUM' INTEGER, 'CueLABEL' TEXT, 'CueNAME' TEXT, 'CueLEN' INTEGER, 'CuePOS' INTEGER, 'CueTYPE' TEXT, 'CueSTATE' INTEGER, 'CueColB' TEXT, 'CueColF' TEXT);");            Log.e("DB tabella ", "creata");        }        @Override        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {            //db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLECN);            //onCreate(db);        }    }    public DBLayer(Context c){        this.ourContext = c;       // handler = null;    }    public DBLayer open()   {    try {        this.ourHelper = new DbHelper(ourContext);        this.ourDatabase = ourHelper.getWritableDatabase();    }    catch (SQLException se){        System.out.println("Got an SQLException: " + se.getMessage());    } return this; }    public void close(){        this.ourHelper.close();    }    public  void updateDB(String LAB, Integer STAT)    {       ourDatabase.execSQL("UPDATE Cues_table set CueSTATE = " + STAT + " WHERE CueLABEL = '" + LAB + "'" );        Log.e("UPDATE DB ", LAB + " state: " + STAT);       new PostTask().execute();    }    public void deleteAll()    {        ourDatabase.execSQL("DELETE from Cues_table");    }    public Integer CountRecords()    {        Cursor cc = ourDatabase.rawQuery("SELECT * from Cues_table",null);        int recCount = cc.getCount();        return recCount;    }    public Cursor Execute(String Query, TipoQuery tipoCmd){        Cursor c = null;        try{            switch(tipoCmd){                case Comando:                    ourDatabase.execSQL(Query);                    break;                case Selezione:                    c = ourDatabase.rawQuery(Query,null);                    break;            }        }catch (Exception e){}        return c;    }    private class PostTask extends AsyncTask<String, Integer, String> {        @Override        protected void onPreExecute() {            super.onPreExecute();        }        @Override        protected String doInBackground(String... params) {            // DO IN BACKGROUND            return "All Done!";        }        @Override        protected void onPostExecute(String result) {            super.onPostExecute(result);            Log.e("POST ", "EXECUTE");            MainActivity main = new MainActivity();            main.UpdateLV();            // POST EXECUTE        }    } }

Do have I to declare it before this way ??
   public DBLayer db = null;

Ron McLeod wrote:Then why not have an instance variable for DBLayer, instantiate it and open the db in onCreate(), use it in UpdateLV(), and close it in onDestroy()?
public class MainActivity extends ... { private DBLayer db; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); db = new DBLayer(this); db.open(); ... } public void UpdateLV(){ // use already opened db } @Override protected void onDestroy() { super.onDestroy(); db.close(); } }