Android R cannot be resolved in Ubuntu

Question

DatabaseConnect is the name of the Android Application Project that has been created in Eclipse in Ubuntu Platform.

One of the java file Inside DatabaseConnect->src->co.package.datewithme is shown Below.

  package com.example.datewithme;


  import android.app.Activity; 
  import android.content.Intent;
  import android.database.Cursor;
  import android.database.sqlite.SQLiteDatabase;
  import android.os.Bundle;
  import android.text.InputType; 
  import android.view.View;
  import android.widget.EditText;
  import android.widget.ImageView; 
  import android.widget.Toast;

 public class Login extends Activity{
 Intent i=null;
 ImageView im=null;
 EditText tv1,tv4;
 boolean flag=false;
 SQLiteDatabase db=null;
 @Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.login);
    im=(ImageView)findViewById(R.id.show_hide2);
    tv1=(EditText)findViewById(R.id.phone2);
    tv4=(EditText)findViewById(R.id.password2);
    db=openOrCreateDatabase("mydb", MODE_PRIVATE, null);
 // db.execSQL("create table if not exists login(name varchar,mobile_no varchar,email_id varchar,password varchar,flag varchar)");

    im.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View arg0) {

            if(flag==false)
            {
                im.setImageResource(R.drawable.hide);
                tv4.setInputType(InputType.TYPE_TEXT_VARIATION_PASSWORD);
                flag=true;
            }
            else
            {
                im.setImageResource(R.drawable.show);
                tv4.setInputType(129);
                flag=false;

            }
        }
    });
  }

   public void action(View v)
   {
     switch(v.getId())
     {
    case R.id.signin2: 
    i=new Intent(this,Signin.class);
    startActivityForResult(i, 500);
    overridePendingTransition(R.anim.slide_in_top, R.anim.slide_out_bottom); 
    finish();
    break;
  case R.id.start:
    String mobile_no=tv1.getText().toString();
    String password=tv4.getText().toString();
    if(mobile_no==null||mobile_no==""||mobile_no.length()<10)
    {
        show("Please Enter Correct mobile number.");
    }
    else if(password==null||password==""||password.length()<6)
    {
        show("Please Enter Correct Password.");
    }
    else
    {       
        Cursor c=db.rawQuery("select * from login where mobile_no='"+mobile_no+"' and password='"+password+"'",null);   
        c.moveToFirst();
        if(c.getCount()>0)
        {
        i=new Intent(this,Welcome.class);
        startActivityForResult(i,500);
        overridePendingTransition(R.anim.slide_in_right, R.anim.slide_out_left); 
        db.close();
        finish();
        }
        else
            show("Wrong Password or Mobile number.");

    }
    break;
    }
       }
  @Override
  protected void onActivityResult(int requestCode, int resultCode, Intent data) {
  overridePendingTransition(R.anim.slide_in_left, R.anim.slide_out_right);
  } 

 public void show(String str)
 {
 Toast.makeText(this, str, Toast.LENGTH_LONG).show();   
 }

}

The error message generated is R cannot be resolved to a variable.But i have R.java file in my Project DatabaseConnect->gen->com.example.Databaseconnect->BuilConfig.java,R.java.

The ScreenShot is shown below.

I Searched all the possibilities for the solution by going through these links. 123

But din't got the proper solution.

I came to know the naming convention got some errors like DatabaseConnect and Datewithme. So i kept the same name to both and then clean and run the project but after that its that its taking previous name itself.

An help is appreciated

Answer 1

Most probably It happens when you have an error in any of your xml files under res folder

You should check:

all of your xml files under res folder fix errors like for example (under drawable folder you have not include icon.png and you are using it as @drawable/icon). When you will check and fix all errors in xml files then Build your project or clean it.

Hope you will understand my words.

Answer 2

Here are some TroubleShooting Steps for this issue.First you may clean the project, then run the project. If this does not work then follow the following links:

Here is the best way to solve this problem:Android Development- Where is my R.Java file?
1.R cannot be resolved - Android error
2.R cannot be resolved to a variable
3.R cannot be resolved to a variable -- mailing list entry
4.Fixed: R cannot be resolved to a variable