Java 使用SharedReferences保存arraylist并在listview中显示
我有两项活动。我想从Note.java获取edittext数据,并将其放在MainActivity.java的listview中。 但是我不能用列表的形式 Note.javaJava 使用SharedReferences保存arraylist并在listview中显示,java,android,Java,Android,我有两项活动。我想从Note.java获取edittext数据,并将其放在MainActivity.java的listview中。 但是我不能用列表的形式 Note.java public class Note extends FragmentActivity implements EditText editText,editText2; @Override protected void onCreate(Bundle savedInstanceState) {
public class Note extends FragmentActivity implements
EditText editText,editText2;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_note);
editText = (EditText)findViewById(R.id.editText);
SharedPreferences sharedPref = getSharedPreferences("note", Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPref.edit();
editor.putString("myKey", editText.getText().toString());
editor.commit();
}
public class MainActivity extends AppCompatActivity{
ListView listView;
List list;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = (ListView) findViewById(R.id.listView);
SharedPreferences sharedPref = getSharedPreferences("note", Context.MODE_PRIVATE);
String baslik = sharedPref.getString("myKey",null);
list = new ArrayList<String>();
ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1,list);
list.add(baslik);
listView.setAdapter(arrayAdapter);
arrayAdapter.notifyDataSetChanged();
}
MainActivity.java
public class Note extends FragmentActivity implements
EditText editText,editText2;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_note);
editText = (EditText)findViewById(R.id.editText);
SharedPreferences sharedPref = getSharedPreferences("note", Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPref.edit();
editor.putString("myKey", editText.getText().toString());
editor.commit();
}
public class MainActivity extends AppCompatActivity{
ListView listView;
List list;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = (ListView) findViewById(R.id.listView);
SharedPreferences sharedPref = getSharedPreferences("note", Context.MODE_PRIVATE);
String baslik = sharedPref.getString("myKey",null);
list = new ArrayList<String>();
ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1,list);
list.add(baslik);
listView.setAdapter(arrayAdapter);
arrayAdapter.notifyDataSetChanged();
}
public类MainActivity扩展了AppCompatActivity{
列表视图列表视图;
名单;
@凌驾
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView=(listView)findViewById(R.id.listView);
SharedReferences SharedReferences=GetSharedReferences(“注意”,Context.MODE\u PRIVATE);
String baslik=sharedPref.getString(“myKey”,null);
列表=新的ArrayList();
ArrayAdapter ArrayAdapter=新的ArrayAdapter(此,
android.R.layout.simple_list_item_1,list);
列表。添加(巴斯利克);
setAdapter(arrayAdapter);
arrayAdapter.notifyDataSetChanged();
}
SharedReferences
只能存储基本数据类型。您不能在SharedReferences
中存储引用类型。对于这种情况,我使用Gson
库
步骤1:将列表转换为字符串
Gson g = new Gson();
String str = g.toJson(list);
步骤2:将字符串存储在SharedReferences
要从SharedReferences
获取数据,必须按如下方式反序列化字符串:
Gson g = new Gson();
Type type = new TypeToken<ArrayList<YourClass>>(){}.getType();
List<YourClass> clazz = g.fromJson(yourString,type);
Gson g=new Gson();
Type Type=new-TypeToken(){}.getType();
List clazz=g.fromJson(您的字符串,类型);
假设您要按SharedReferences保存和加载列表:
public static final String NEWS = "news";
private SharedPreferences mPreferences;
public void saveNews(List<ResponseNews> news) {
mPreferences.edit().putString(NEWS, new Gson().toJson(news)).commit();
}
public List<ResponseNews> loadNews() {
return new Gson().fromJson(mPreferences.getString(NEWS, ""), new TypeToken<List<ResponseNews>>() {
}.getType());
}
公共静态最终字符串NEWS=“NEWS”;
私人共享参考文献;
公共新闻(列表新闻){
mPreferences.edit().putString(NEWS,new Gson().toJson(NEWS)).commit();
}
公共列表loadNews(){
返回新的Gson(){
}.getType());
}
Hi Elbis,欢迎来到StackOverflow!您必须更好地解释您的代码发生了什么,您的应用程序正在崩溃或出现错误?发布错误日志。我看到您正试图解决SharedReferences的问题,这是必要的,还是您不知道该怎么做?谢谢@Shermano。我没有收到错误,但应用程序是crashing。不需要共享参考。我不知道怎么做。