如何在 onSaveInstanceState 中保存
How to save in onSaveInstanceState
我在我的应用程序中使用外部卡片库 (gabrielemariotti cardlib)。
特别是我正在使用 CardRecyclerView extends RecyclerView 和 CardArrayRecyclerViewAdapter extends BaseRecyclerViewAdapter。
我有两个活动 Main Activity（使用 CardRecyclerView）和 ProductCard activity
我的目标是在我从其他活动 (ProductCard) 返回或打开 MainActivity 方向时将所有卡片保存在 MainActivity 中。
不幸的是，我不明白如何在 onSaveInstanceState 中保存我的 'mRecyclerView'。有人可以帮忙吗？
package com.example.dmitry.myfoodbasket;
import android.content.Intent;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Toast;
import java.io.Serializable;
import java.util.ArrayList;
import it.gmariotti.cardslib.library.cards.actions.BaseSupplementalAction;
import it.gmariotti.cardslib.library.cards.actions.IconSupplementalAction;
import it.gmariotti.cardslib.library.cards.material.MaterialLargeImageCard;
import it.gmariotti.cardslib.library.internal.Card;
import it.gmariotti.cardslib.library.internal.CardHeader;
import it.gmariotti.cardslib.library.recyclerview.internal.CardArrayRecyclerViewAdapter;
import it.gmariotti.cardslib.library.recyclerview.view.CardRecyclerView;
public class MainActivity extends AppCompatActivity {
final String LOG_TAG = "myLogs";
ArrayList<BaseSupplementalAction> actions;
ArrayList<Card> cards;
MaterialLargeImageCard card;
CardArrayRecyclerViewAdapter mCardArrayAdapter;
CardRecyclerView mRecyclerView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.d(LOG_TAG, "onCreate");
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
/*Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();*/
cards.add(card);
mCardArrayAdapter.notifyDataSetChanged();
}
});
cards = new ArrayList<Card>();
card =
MaterialLargeImageCard.with(this)
.setTextOverImage("Italian Beaches")
.useDrawableId(R.drawable.im_beach)
.setupSupplementalActions(R.layout.carddemo_native_material_supplemental_actions_large_icon,actions )
.build();
cards.add(card);
card.setOnClickListener(new Card.OnCardClickListener() {
@Override
public void onClick(Card card, View view) {
Intent intent=new Intent(MainActivity.this,ProductCard.class);
startActivity(intent);
}});
actions = new ArrayList<BaseSupplementalAction>();
IconSupplementalAction t1 = new IconSupplementalAction(this, R.id.ic1);
t1.setOnActionClickListener(new BaseSupplementalAction.OnActionClickListener() {
@Override
public void onClick(Card card, View view) {
Toast.makeText(MainActivity.this, " Click on Text SHARE ", Toast.LENGTH_SHORT).show();
}
});
actions.add(t1);
IconSupplementalAction t2 = new IconSupplementalAction(this, R.id.ic2);
t2.setOnActionClickListener(new BaseSupplementalAction.OnActionClickListener() {
@Override
public void onClick(Card card, View view) {
Toast.makeText(MainActivity.this," Click on Text LEARN ", Toast.LENGTH_SHORT).show();
}
});
actions.add(t2);
IconSupplementalAction t3 = new IconSupplementalAction(this, R.id.ic3);
t3.setOnActionClickListener(new BaseSupplementalAction.OnActionClickListener() {
@Override
public void onClick(Card card, View view) {
Toast.makeText(MainActivity.this, " Карточка удалена ", Toast.LENGTH_SHORT).show();
cards.remove(card);
mCardArrayAdapter.notifyDataSetChanged();
}
});
actions.add(t3);
mCardArrayAdapter = new CardArrayRecyclerViewAdapter(this, cards);
mRecyclerView = (CardRecyclerView) this.findViewById(R.id.carddemo_recyclerview);
mRecyclerView.setHasFixedSize(false);
mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
if (mRecyclerView != null) {
mRecyclerView.setAdapter(mCardArrayAdapter);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
您的 activity 将在用户每次旋转屏幕时被销毁并重新创建。当屏幕改变方向时，系统会破坏并重新创建前景 activity。
要保存有关 activity 状态的其他数据，您必须覆盖
onSaveInstanceState()
回调方法
@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
// Save the user's current game state
savedInstanceState.putInt(STATE_SCORE, mCurrentScore);
savedInstanceState.putInt(STATE_LEVEL, mCurrentLevel);
// Always call the superclass so it can save the view hierarchy state
super.onSaveInstanceState(savedInstanceState); }
现在您可以在上面的 Bundle 实例中保存特定的字符串、整数或事件自定义 Parelable 对象。
当您的 Activity 重新创建时，只需检查 onCreate() 中的 Bundle onSavedInstance 是否为 null
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState); // Always call the superclass first
// Check whether we're recreating a previously destroyed instance
if (savedInstanceState != null) {
// Restore value of members from saved state and populare your RecyclerView again
mCurrentScore = savedInstanceState.getInt(STATE_SCORE);
mCurrentLevel = savedInstanceState.getInt(STATE_LEVEL);
} else {
// Probably initialize members with default values for a new instance
}
您可以将上面的内容替换为您要保存的数据，然后使用您保存在 savedInstance 中的数据作为键值对重新填充您的视图，如 RecyclerView 等。
请记住，Bundle 并不意味着存储大量数据。
抱歉，如果某些代码标识不是很清楚，那么 post 从移动设备上回答就更难了。
如需更清楚的解释，请参阅此 official guide
我在我的应用程序中使用外部卡片库 (gabrielemariotti cardlib)。 特别是我正在使用 CardRecyclerView extends RecyclerView 和 CardArrayRecyclerViewAdapter extends BaseRecyclerViewAdapter。 我有两个活动 Main Activity（使用 CardRecyclerView）和 ProductCard activity
我的目标是在我从其他活动 (ProductCard) 返回或打开 MainActivity 方向时将所有卡片保存在 MainActivity 中。 不幸的是，我不明白如何在 onSaveInstanceState 中保存我的 'mRecyclerView'。有人可以帮忙吗？
package com.example.dmitry.myfoodbasket;
import android.content.Intent;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Toast;
import java.io.Serializable;
import java.util.ArrayList;
import it.gmariotti.cardslib.library.cards.actions.BaseSupplementalAction;
import it.gmariotti.cardslib.library.cards.actions.IconSupplementalAction;
import it.gmariotti.cardslib.library.cards.material.MaterialLargeImageCard;
import it.gmariotti.cardslib.library.internal.Card;
import it.gmariotti.cardslib.library.internal.CardHeader;
import it.gmariotti.cardslib.library.recyclerview.internal.CardArrayRecyclerViewAdapter;
import it.gmariotti.cardslib.library.recyclerview.view.CardRecyclerView;
public class MainActivity extends AppCompatActivity {
final String LOG_TAG = "myLogs";
ArrayList<BaseSupplementalAction> actions;
ArrayList<Card> cards;
MaterialLargeImageCard card;
CardArrayRecyclerViewAdapter mCardArrayAdapter;
CardRecyclerView mRecyclerView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.d(LOG_TAG, "onCreate");
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
/*Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();*/
cards.add(card);
mCardArrayAdapter.notifyDataSetChanged();
}
});
cards = new ArrayList<Card>();
card =
MaterialLargeImageCard.with(this)
.setTextOverImage("Italian Beaches")
.useDrawableId(R.drawable.im_beach)
.setupSupplementalActions(R.layout.carddemo_native_material_supplemental_actions_large_icon,actions )
.build();
cards.add(card);
card.setOnClickListener(new Card.OnCardClickListener() {
@Override
public void onClick(Card card, View view) {
Intent intent=new Intent(MainActivity.this,ProductCard.class);
startActivity(intent);
}});
actions = new ArrayList<BaseSupplementalAction>();
IconSupplementalAction t1 = new IconSupplementalAction(this, R.id.ic1);
t1.setOnActionClickListener(new BaseSupplementalAction.OnActionClickListener() {
@Override
public void onClick(Card card, View view) {
Toast.makeText(MainActivity.this, " Click on Text SHARE ", Toast.LENGTH_SHORT).show();
}
});
actions.add(t1);
IconSupplementalAction t2 = new IconSupplementalAction(this, R.id.ic2);
t2.setOnActionClickListener(new BaseSupplementalAction.OnActionClickListener() {
@Override
public void onClick(Card card, View view) {
Toast.makeText(MainActivity.this," Click on Text LEARN ", Toast.LENGTH_SHORT).show();
}
});
actions.add(t2);
IconSupplementalAction t3 = new IconSupplementalAction(this, R.id.ic3);
t3.setOnActionClickListener(new BaseSupplementalAction.OnActionClickListener() {
@Override
public void onClick(Card card, View view) {
Toast.makeText(MainActivity.this, " Карточка удалена ", Toast.LENGTH_SHORT).show();
cards.remove(card);
mCardArrayAdapter.notifyDataSetChanged();
}
});
actions.add(t3);
mCardArrayAdapter = new CardArrayRecyclerViewAdapter(this, cards);
mRecyclerView = (CardRecyclerView) this.findViewById(R.id.carddemo_recyclerview);
mRecyclerView.setHasFixedSize(false);
mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
if (mRecyclerView != null) {
mRecyclerView.setAdapter(mCardArrayAdapter);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
您的 activity 将在用户每次旋转屏幕时被销毁并重新创建。当屏幕改变方向时，系统会破坏并重新创建前景 activity。
要保存有关 activity 状态的其他数据，您必须覆盖 onSaveInstanceState() 回调方法
@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
// Save the user's current game state
savedInstanceState.putInt(STATE_SCORE, mCurrentScore);
savedInstanceState.putInt(STATE_LEVEL, mCurrentLevel);
// Always call the superclass so it can save the view hierarchy state
super.onSaveInstanceState(savedInstanceState); }
现在您可以在上面的 Bundle 实例中保存特定的字符串、整数或事件自定义 Parelable 对象。 当您的 Activity 重新创建时，只需检查 onCreate() 中的 Bundle onSavedInstance 是否为 null
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState); // Always call the superclass first
// Check whether we're recreating a previously destroyed instance
if (savedInstanceState != null) {
// Restore value of members from saved state and populare your RecyclerView again
mCurrentScore = savedInstanceState.getInt(STATE_SCORE);
mCurrentLevel = savedInstanceState.getInt(STATE_LEVEL);
} else {
// Probably initialize members with default values for a new instance
}
您可以将上面的内容替换为您要保存的数据，然后使用您保存在 savedInstance 中的数据作为键值对重新填充您的视图，如 RecyclerView 等。
请记住，Bundle 并不意味着存储大量数据。
抱歉，如果某些代码标识不是很清楚，那么 post 从移动设备上回答就更难了。
如需更清楚的解释，请参阅此 official guide