btn1.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        if (ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.READ_CONTACTS) != PackageManager.PERMISSION_GRANTED
                || ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.WRITE_CONTACTS) != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.READ_CONTACTS, Manifest.permission.WRITE_CONTACTS}, PERMISSION_REQUEST_CODE);
        } else {
                     ContentResolver contentResolver = getContentResolver();
            Cursor cursor = contentResolver.query(
                    ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null, null, null, ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME + " ASC");

            EditText edit_find = findViewById(R.id.tv_find);
            string_find = edit_find.getText().toString();

            EditText replace_find = findViewById(R.id.tv_raplece);
            string_replace = replace_find.getText().toString();

            if (cursor != null) {
                while (cursor.moveToNext()) {
                    String name = cursor.getString(cursor.getColumnIndex(ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME));

                    if (name.contains(string_find)) {
                        name = name.replace(string_find, string_replace);
                        values.put(ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME, name);

                        contentResolver.update(
                                ContactsContract.CommonDataKinds.Phone.CONTENT_URI, values,
                                ContactsContract.CommonDataKinds.Phone.CONTACT_ID + "=?",
                                new String[]{cursor.getString(cursor.getColumnIndex(ContactsContract.CommonDataKinds.Phone.CONTACT_ID))}
                        );
                    }
                }
                cursor.close();
            }
        }
    }
});