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/*
* Copyright (C) 2017 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.arch.persistence.room.integration.testapp;
import android.arch.lifecycle.LifecycleRegistry;
import android.arch.lifecycle.LiveData;
import android.arch.lifecycle.Observer;
import android.arch.lifecycle.ViewModelProviders;
import android.arch.paging.PagedList;
import android.arch.persistence.room.integration.testapp.database.Customer;
import android.arch.persistence.room.integration.testapp.database.LastNameAscCustomerDataSource;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.Button;
/**
* Sample PagedList activity which uses Room.
*/
public class RoomPagedListActivity extends AppCompatActivity {
private RecyclerView mRecyclerView;
private PagedListCustomerAdapter mAdapter;
private static final String STRING_KEY = "STRING_KEY";
private static final String INT_KEY = "INT_KEY";
@Override
protected void onCreate(final Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_recycler_view);
final CustomerViewModel viewModel = ViewModelProviders.of(this)
.get(CustomerViewModel.class);
mRecyclerView = findViewById(R.id.recyclerview);
mAdapter = new PagedListCustomerAdapter();
mRecyclerView.setAdapter(mAdapter);
LiveData<PagedList<Customer>> livePagedList;
if (useKeyedQuery()) {
String key = null;
if (savedInstanceState != null) {
key = savedInstanceState.getString(STRING_KEY);
mAdapter.setScrollToKey(key);
}
livePagedList = viewModel.getLivePagedList(key);
} else {
int position = 0;
if (savedInstanceState != null) {
position = savedInstanceState.getInt(INT_KEY);
mAdapter.setScrollToPosition(position);
}
livePagedList = viewModel.getLivePagedList(position);
}
livePagedList.observe(this, new Observer<PagedList<Customer>>() {
@Override
public void onChanged(@Nullable PagedList<Customer> items) {
mAdapter.setList(items);
}
});
final Button button = findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
viewModel.insertCustomer();
}
});
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
PagedList<Customer> list = mAdapter.getCurrentList();
if (list == null) {
// Can't find anything to restore
return;
}
LinearLayoutManager layoutManager = (LinearLayoutManager) mRecyclerView.getLayoutManager();
final int targetPosition = layoutManager.findFirstVisibleItemPosition();
if (useKeyedQuery()) {
Customer customer = list.get(targetPosition);
if (customer != null) {
String key = LastNameAscCustomerDataSource.getKeyStatic(customer);
outState.putString(STRING_KEY, key);
}
} else {
// NOTE: in the general case, we can't just rely on RecyclerView/LinearLayoutManager to
// preserve position, because of position offset which is present when using an
// uncounted, non-keyed source).
int absolutePosition = targetPosition + list.getPositionOffset();
outState.putInt(INT_KEY, absolutePosition);
}
}
protected boolean useKeyedQuery() {
return false;
}
private LifecycleRegistry mLifecycleRegistry = new LifecycleRegistry(this);
@Override
public LifecycleRegistry getLifecycle() {
return mLifecycleRegistry;
}
}
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