Realm Integration in Android

RLMApplication.java

public class RLMApplication extends Application {

    @Override
    public void onCreate() {
        super.onCreate();
        RealmConfiguration realmConfiguration = new RealmConfiguration.Builder(this)
                .name(Realm.DEFAULT_REALM_NAME)
                .schemaVersion(0)
                .deleteRealmIfMigrationNeeded()
                .build();
        Realm.setDefaultConfiguration(realmConfiguration);
    }
}

Contacts.java

public class Contacts extends RealmObject {

    private String name;
    private String email;
    private String address;
    private int age;
    private long id;

    private RealmList<Friends> friends;

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public RealmList<Friends> getFriends() {
        return friends;
    }

    public void setFriends(RealmList<Friends> friends) {
        this.friends = friends;
    }
}


Friends.java

public class Friends extends RealmObject {

    private long fid;
    private String name;
    private String id;

    public long getFid() {
        return fid;
    }

    public void setFid(long fid) {
        this.fid = fid;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }


    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }
}

MainActivity.java

public class MainActivity extends AppCompatActivity {


    TextView mTextViewAdd;
    ListView mListView;
    Realm mRealm;
    CustomAdapter mCustomAdapter;
    LayoutInflater mLayoutInflater;
    RealmResults<Contacts> mContactses;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mRealm = Realm.getDefaultInstance();
        // mContactses = new RealmResults<Contacts>();
        mTextViewAdd = (TextView) findViewById(R.id.txt_add);
        mListView = (ListView) findViewById(R.id.list);
        mLayoutInflater = getLayoutInflater();
        setRealmData();
        mTextViewAdd.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                View content = mLayoutInflater.inflate(R.layout.edit_item, null);
                final EditText editTitle = (EditText) content.findViewById(R.id.title);

                AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
                builder.setView(content)
                        .setTitle("Add Contact")
                        .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {

                            @Override
                            public void onClick(DialogInterface dialog, int which) {

                                mRealm.beginTransaction();
                                Contacts contact = mRealm.createObject(Contacts.class);
                                contact.setId(System.currentTimeMillis());
                                contact.setName(editTitle.getText().toString());
                                contact.setEmail("Contact@hostname.com");
                                contact.setAddress("Contact's Address");
                                contact.setAge(20);
                                mRealm.commitTransaction();

                                mCustomAdapter.notifyDataSetChanged();

                            }
                        })
                        .setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() {

                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                dialog.dismiss();
                            }
                        });
                AlertDialog dialog = builder.create();
                dialog.show();
            }
        });

    }

    private void setRealmData() {

        RealmQuery<Contacts> query = mRealm.where(Contacts.class);
        mContactses = query.findAll();
        mCustomAdapter = new CustomAdapter(MainActivity.this, mContactses, true);
        mListView.setAdapter(mCustomAdapter);

    }

    public class CustomAdapter extends RealmBaseAdapter<Contacts> {

        Context mActivity;
        RealmResults<Contacts> list;

        public CustomAdapter(Context context, RealmResults<Contacts> realmResults, boolean automaticUpdate) {
            super(context, realmResults, automaticUpdate);
            this.list = realmResults;
            this.mActivity = context;

        }

        @Override
        public int getCount() {
            return list.size();
        }


        @Override
        public long getItemId(int i) {
            return i;
        }

        @Override
        public View getView(final int i, View convertView, ViewGroup viewGroup) {
            LayoutInflater mInflater = (LayoutInflater)
                    mActivity.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
            convertView = mInflater.inflate(R.layout.row_item, null);
            TextView mTextViewName = (TextView) convertView.findViewById(R.id.txt_name);
            Button mButtonEdit = (Button) convertView.findViewById(R.id.bt_edt);
            Button mButtonDelete = (Button) convertView.findViewById(R.id.bt_del);
            Button mButtonView= (Button) convertView.findViewById(R.id.bt_view);

            mTextViewName.setText(list.get(i).getName());
            mButtonView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    long cid=mContactses.get(i).getId();
                    Intent mIntent=new Intent(MainActivity.this,FriendActivity.class).setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                    Bundle mBundle=new Bundle();
                    mBundle.putString("id",String.valueOf(cid));
                    mIntent.putExtras(mBundle);
                    startActivity(mIntent);
                }
            });
            mButtonEdit.setOnClickListener(new View.OnClickListener() {
                @Override

                public void onClick(View v) {
                    View content = mLayoutInflater.inflate(R.layout.edit_item, null);
                    final EditText editTitle = (EditText) content.findViewById(R.id.title);
                    editTitle.setText(list.get(i).getName());
                    AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
                    builder.setView(content)
                            .setTitle("Add Contact")
                            .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {

                                @Override
                                public void onClick(DialogInterface dialog, int which) {

                                    RealmResults<Contacts> results = mRealm.where(Contacts.class).findAll();

                                    mRealm.beginTransaction();
                                    results.get(i).setName(editTitle.getText().toString());

                                    mRealm.commitTransaction();

                                    notifyDataSetChanged();

                                }
                            })
                            .setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() {

                                @Override
                                public void onClick(DialogInterface dialog, int which) {
                                    dialog.dismiss();
                                }
                            });
                    AlertDialog dialog = builder.create();
                    dialog.show();
                }
            });
            mButtonDelete.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    mRealm.beginTransaction();
                    list.remove(i);
                    mRealm.commitTransaction();
                    mCustomAdapter.notifyDataSetChanged();
                }
            });
            return convertView;
        }
    }
}

FriendActivity.java

public class FriendActivity extends AppCompatActivity {

    TextView mTextViewAdd;
    ListView mListView;
    Realm mRealm;
    CustomAdapter mCustomAdapter;
    LayoutInflater mLayoutInflater;
    RealmResults<Friends> mContactses;
    Bundle mBundle;
    long cid;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mRealm = Realm.getDefaultInstance();
        mBundle = getIntent().getExtras();
        cid = Long.parseLong(mBundle.getString("id"));
        mTextViewAdd = (TextView) findViewById(R.id.txt_add);
        mListView = (ListView) findViewById(R.id.list);
        mLayoutInflater = getLayoutInflater();
        setRealmData();
        mTextViewAdd.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                View content = mLayoutInflater.inflate(R.layout.edit_item, null);
                final EditText editTitle = (EditText) content.findViewById(R.id.title);

                AlertDialog.Builder builder = new AlertDialog.Builder(FriendActivity.this);
                builder.setView(content)
                        .setTitle("Add Friend")
                        .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {

                            @Override
                            public void onClick(DialogInterface dialog, int which) {

                                mRealm.beginTransaction();
                                Friends contact = mRealm.createObject(Friends.class);
                                contact.setFid(System.currentTimeMillis());
                                contact.setId(String.valueOf(cid));
                                contact.setName(editTitle.getText().toString());
                                mRealm.commitTransaction();

                                mCustomAdapter.notifyDataSetChanged();

                            }
                        })
                        .setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() {

                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                dialog.dismiss();
                            }
                        });
                AlertDialog dialog = builder.create();
                dialog.show();
            }
        });

    }

    private void setRealmData() {

        RealmQuery<Friends> query = mRealm.where(Friends.class);
        query.contains("id", String.valueOf(cid));
        mContactses = query.findAll();
        mCustomAdapter = new CustomAdapter(FriendActivity.this, mContactses, true);
        mListView.setAdapter(mCustomAdapter);

    }

    public class CustomAdapter extends RealmBaseAdapter<Friends> {

        Context mActivity;
        RealmResults<Friends> list;
    

        public CustomAdapter(Context context, RealmResults<Friends> realmResults, boolean automaticUpdate) {
            super(context, realmResults, automaticUpdate);
            this.list = realmResults;
            this.mActivity = context;

        }

        @Override
        public int getCount() {
            return list.size();
        }


        @Override
        public long getItemId(int i) {
            return i;
        }

        @Override
        public View getView(final int i, View convertView, ViewGroup viewGroup) {
            LayoutInflater mInflater = (LayoutInflater)
                    mActivity.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
            convertView = mInflater.inflate(R.layout.row_item, null);
            TextView mTextViewName = (TextView) convertView.findViewById(R.id.txt_name);
            Button mButtonEdit = (Button) convertView.findViewById(R.id.bt_edt);
            Button mButtonDelete = (Button) convertView.findViewById(R.id.bt_del);
            mTextViewName.setText(list.get(i).getName());
            mButtonEdit.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    View content = mLayoutInflater.inflate(R.layout.edit_item, null);
                    final EditText editTitle = (EditText) content.findViewById(R.id.title);
                    editTitle.setText(list.get(i).getName());
                    AlertDialog.Builder builder = new AlertDialog.Builder(FriendActivity.this);
                    builder.setView(content)
                            .setTitle("Add Friend")
                            .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {

                                @Override
                                public void onClick(DialogInterface dialog, int which) {

                                    RealmResults<Friends> results = mRealm.where(Friends.class).findAll();

                                    mRealm.beginTransaction();
                                    results.get(i).setName(editTitle.getText().toString());

                                    mRealm.commitTransaction();

                                    notifyDataSetChanged();

                                }
                            })
                            .setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() {

                                @Override
                                public void onClick(DialogInterface dialog, int which) {
                                    dialog.dismiss();
                                }
                            });
                    AlertDialog dialog = builder.create();
                    dialog.show();
                }
            });
            mButtonDelete.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    mRealm.beginTransaction();
                    list.remove(i);
                    mRealm.commitTransaction();
                    mCustomAdapter.notifyDataSetChanged();
                }
            });
            return convertView;
        }
    }

}