Intent intent = new Intent(this, MaDeuxiemeActivity.class);
intent.putExtra("edittext", str);
intent.putExtra("nbLettre", nbLettre);
startActivity(intent);

 
Intent intent = getIntent();
    if (intent != null){
        String str = "";
        if (intent.hasExtra("edittext")){
            str = intent.getStringExtra("edittext");
        }
        int nbLettre = intent.getIntExtra("nbLettre", 0);
        TextView textView = (TextView) findViewById(R.id.tv1);
        textView.setText(str + "; " + nbLettre);
    }

 
public class MainActivity extends AppCompatActivity {
    public static MainActivity activity;
    public int currentPage;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        MainActivity.activity = this;
    }
    private void launchPageReader(....) {
       ....
      startActivity(new Intent(this, PageReaderActivity.class));
    }
 
}
 
public class PageReaderActivity  extends AppCompatActivity {
    private int currentPage= 0;
    @Override
    public void onResume(){
        super.onResume();
        this.currentPage = MainActivity.activity.currentPage;
}