Simple example of loader in android

• User.java

public class User {
    private String mName;
    public User(String mName) {
        this.mName = mName;
    }
    public String getmName() {
        return mName;
    }
    public void setmName(String mName) {
        this.mName = mName;
    }
}

---

• DataLoader.java

public class DataLoader extends Loader<List<User>> {
    private List<User> mData;
    public DataLoader(Context context) {
        super(context);
    }
    @Override
    protected void onStartLoading() {
        if (mData != null) {
            deliverResult(mData);
        }
        if (takeContentChanged() || mData == null) {
            forceLoad();
        }
    }
    @Override
    public void forceLoad() {
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        List<User> data = new ArrayList<>();
        data.add(new User("Tuan"));
        data.add(new User("Thuy"));
        data.add(new User("Hanh"));
        data.add(new User("Linh"));
        data.add(new User("Huyen"));
        data.add(new User("Dan"));
        data.add(new User("Tam"));
        data.add(new User("Thuy"));
        deliverResult(data);
    }
    @Override
    public void deliverResult(List<User> data) {
        mData = data;
        super.deliverResult(data);
    }
    @Override
    protected void onReset() {
        super.onReset();
        mData = null;
    }
}

---

• activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="16dp"
    android:paddingLeft="16dp"
    android:paddingRight="16dp"
    android:paddingTop="16dp">
    <TextView
        android:id="@+id/tvResult"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!" />
</ScrollView>

---

• MainActivity.java

public class MainActivity extends AppCompatActivity 
        implements LoaderManager.LoaderCallbacks<List<User>> {
    private TextView tvResult;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tvResult = (TextView) findViewById(R.id.tvResult);
        getSupportLoaderManager().initLoader(0, null, this);
    }
    @Override
    public Loader<List<User>> onCreateLoader(int id, Bundle args) {
        return new DataLoader(MainActivity.this);
    }
    @Override
    public void onLoadFinished(Loader<List<User>> loader, List<User> data) {
        StringBuilder stringBuilder = new StringBuilder();
        for (User user : data) {
            stringBuilder.append(user.getmName() + "\n");
        }
        tvResult.setText(stringBuilder.toString());
    }
    @Override
    public void onLoaderReset(Loader<List<User>> loader) {
        tvResult.setText("");
    }
}

• Result