[英]Saving listview content to sd-card in android
我正在制作一个需要将listview项保存到sdcard的android应用程序。 我正在使用一个动态列表视图,用户可以从中删除项目并向其中添加项目。 如果应用程序被破坏或用户单击后退按钮,我希望listview保存项目。 基本上是在活动被破坏时。 请帮助,并非常感谢! 到目前为止,我正在使用此代码:
public class NotesActivity extends ListActivity implements OnClickListener {
/** Called when the activity is first created. */
List<String> myList = new ArrayList<String>();
EditText AddItemToListViewEditText;
Button AddItemToListView, AddItemToListViewButton, CancelButton, DeleteButton,CancelButton2, DeleteAllButton;
LinearLayout AddItemToListViewLinearLayout, DeleteItemFromListViewLinearLayout, DeleteAllItemsFromListViewLinearLayout;
public int DeleteIndexNumber;
static final String[] COUNTRIES = new String[] {
"Matte på A1 med Ole", "Engelsk på klasserommet", "Film på A1 etter friminuttet"
};
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.notes);
setListAdapter((ListAdapter) new ArrayAdapter<String>(this, R.layout.list_item, COUNTRIES));
setListAdapter((ListAdapter) new ArrayAdapter<String>(this, R.layout.list_item, myList));
ListView lv = getListView();
lv.setTextFilterEnabled(true);
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// When clicked, show a toast with the TextView text
Toast.makeText(getApplicationContext(), "Note: " + ((TextView) view).getText(),
Toast.LENGTH_SHORT).show();
DeleteIndexNumber = position;
DeleteItemFromListViewLinearLayout = (LinearLayout)findViewById(R.id.DeleteItemFromListViewLinearLayout);
DeleteItemFromListViewLinearLayout.setVisibility(View.VISIBLE);
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu meny) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.listviewmenubuttons, meny);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch(item.getItemId()) {
case R.id.AddItemToListView:
AddItemToListViewButton = (Button)findViewById(R.id.AddItemToListViewButton);
CancelButton = (Button)findViewById(R.id.CancelButton);
DeleteButton = (Button)findViewById(R.id.DeleteButton);
CancelButton.setOnClickListener(this);
DeleteButton.setOnClickListener(this);
AddItemToListViewLinearLayout = (LinearLayout)findViewById(R.id.AddItemToListViewLinearLayout);
AddItemToListViewButton.setOnClickListener(this);
AddItemToListViewLinearLayout.setVisibility(View.VISIBLE);
break;
case R.id.DeleteAllNotes:
DeleteAllItemsFromListViewLinearLayout = (LinearLayout)findViewById(R.id.DeleteAllItemsFromListViewLinearLayout);
DeleteAllItemsFromListViewLinearLayout.setVisibility(View.VISIBLE);
CancelButton2 = (Button)findViewById(R.id.CancelButton2);
DeleteAllButton = (Button)findViewById(R.id.DeleteAllButton);
CancelButton2.setOnClickListener(this);
DeleteAllButton.setOnClickListener(this);
break;
}
return true;
}
public void onClick(View src) {
switch(src.getId()) {
case R.id.AddItemToListViewButton:
AddItemToListViewEditText = (EditText)findViewById(R.id.AddItemToListViewEditText);
myList.add(AddItemToListViewEditText.getText().toString());
((ArrayAdapter)getListView().getAdapter()).notifyDataSetChanged();
AddItemToListViewEditText.setText("");
AddItemToListViewEditText.clearFocus();
InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
imm.toggleSoftInput (InputMethodManager.SHOW_FORCED, InputMethodManager.RESULT_HIDDEN);
imm.toggleSoftInput(InputMethodManager.SHOW_FORCED, 0);
AddItemToListViewLinearLayout.setVisibility(View.GONE);
break;
case R.id.CancelButton:
DeleteItemFromListViewLinearLayout = (LinearLayout)findViewById(R.id.DeleteItemFromListViewLinearLayout);
DeleteItemFromListViewLinearLayout.setVisibility(View.INVISIBLE);
break;
case R.id.DeleteButton:
myList.remove(DeleteIndexNumber);
((ArrayAdapter)getListView().getAdapter()).notifyDataSetChanged();
DeleteItemFromListViewLinearLayout = (LinearLayout)findViewById(R.id.DeleteItemFromListViewLinearLayout);
DeleteItemFromListViewLinearLayout.setVisibility(View.INVISIBLE);
break;
case R.id.DeleteAllButton:
myList.removeAll(myList);
((ArrayAdapter)getListView().getAdapter()).notifyDataSetChanged();
DeleteAllItemsFromListViewLinearLayout = (LinearLayout)findViewById(R.id.DeleteAllItemsFromListViewLinearLayout);
DeleteAllItemsFromListViewLinearLayout.setVisibility(View.INVISIBLE);
break;
case R.id.CancelButton2:
DeleteAllItemsFromListViewLinearLayout = (LinearLayout)findViewById(R.id.DeleteAllItemsFromListViewLinearLayout);
DeleteAllItemsFromListViewLinearLayout.setVisibility(View.INVISIBLE);
break;
}
}
}
您可以查看官方的数据存储指南。 由于您的ListView内容很大,因此可以将其存储到SQLite数据库中。 该指南的链接如下:-
http://developer.android.com/guide/topics/data/data-storage.html
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