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當我的android應用程序更改片段或將設備位置更改爲橫向時，我正面臨一個問題。列表視圖中的內容將被刪除或刪除。我已經閱讀了一些關於它的信息，我將需要在「onSaveInstanceState」下保存listview的內容/數據，並在片段重新創建時使用「onCreate」將保存的內容/數據放回到列表視圖中。但我不確定要在「onSaveInstnceState」部分下鍵入什麼內容。請幫助我做到這一點。從我讀到的有些人說這很容易克服，但對我來說，它似乎是一個巨大的壁壘來克服。如何在更改片段後在listview中保留內容
下面是代碼。有些部分已經改變。
public class Tab extends Fragment {
ArrayList<ExpaneseModel> beta1;
ListView listView;
private static ExpansesCustomAdapter adapter;
@Override
public void onCreate (Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if(savedInstanceState==null){
}else{
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootview = inflater.inflate(R.layout.tab2, container, false);
Button Add = (Button)rootview.findViewById(R.id.btnAdd);
listView=(ListView)rootview.findViewById(R.id.list);
beta1= new ArrayList<>();
listView.setAdapter(adapter);
Add.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
final Dialog dialogsetting = new Dialog(getActivity());
dialogsetting.requestWindowFeature(Window.FEATURE_NO_TITLE);
dialogsetting.setContentView(R.layout.entry_input);
final EditText one = (EditText)dialogsetting.findViewById(R.id.et_one);
final EditText two = (EditText)dialogsetting.findViewById(R.id.et_two);
Button ok = (Button)dialogsetting.findViewById(R.id.btnOK);
Button cancel = (Button)dialogsetting.findViewById(R.id.btnCancel);
ok.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
dataModels.add(new ExpaneseModel(one.getText().toString(), two.getText().toString()));
adapter.notifyDataSetChanged();
dialogsetting.dismiss();
}
});
cancel.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
dialogsetting.dismiss();
}
});
dialogsetting.show();
}
});
return rootview;
}
@Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
//I am not sure what code to type in here
} }
下面是ExpaneseModel：
公共類ExpaneseModel {
String one;
String two;
public ExpaneseModel(String one, String two) {
this.one=one;
this.two=two;
}
public String getOne() {
return one;
}
public String getTwo() {
return two;
}}
下面是自定義適配器類：
public class ExpansesCustomAdapter extends ArrayAdapter<ExpaneseModel> implements View.OnClickListener{
private ArrayList<ExpaneseModel> dataSet;
Context mContext;
// View lookup cache
private static class ViewHolder {
TextView txtOne;
TextView txtTwo;
}
public ExpansesCustomAdapter(ArrayList<ExpaneseModel> data, Context context) {
super(context, R.layout.expanses_row_item, data);
this.dataSet = data;
this.mContext=context;
}
@Override
public void onClick(View v) {
int position=(Integer) v.getTag();
Object object= getItem(position);
ExpaneseModel dataModel=(ExpaneseModel) object;
}
private int lastPosition = -1;
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// Get the data item for this position
ExpaneseModel dataModel = getItem(position);
// Check if an existing view is being reused, otherwise inflate the view
ViewHolder viewHolder; // view lookup cache stored in tag
final View result;
if (convertView == null) {
viewHolder = new ViewHolder();
LayoutInflater inflater = LayoutInflater.from(getContext());
convertView = inflater.inflate(R.layout.expanses_row_item, parent, false);
viewHolder.txtOne = (TextView) convertView.findViewById(R.id.one);
viewHolder.txtTwo = (TextView) convertView.findViewById(R.id.two)
result=convertView;
convertView.setTag(viewHolder);
} else {
viewHolder = (ViewHolder) convertView.getTag();
result=convertView;
}
Animation animation = AnimationUtils.loadAnimation(mContext, (position > lastPosition) ? R.anim.up_from_bottom : R.anim.down_from_top);
result.startAnimation(animation);
lastPosition = position;
viewHolder.txtName.setText(dataModel.getName());
viewHolder.txtType.setText(dataModel.getAmount());
viewHolder.info.setOnClickListener(this);
viewHolder.info.setTag(position);
// Return the completed view to render on screen
return convertView;
}
}
我看不到您在哪裏創建適配器。考慮使arraylist靜態。在改變方向時，活動不必被破壞：[我們如何在任何活動中使用onNewIntent（）？]（https://stackoverflow.com/questions/8357200/how-we-can-use-onnewintent-in-任何活動）和[活動重新啓動Android]（https://stackoverflow.com/questions/456211/activity-restart-on-rotation-android） – RonTLV