我在一个活动中有一个列表视图，在自定义适配器中有一个信息图标。当用户点击该信息按钮时，下一个活动将打开，当用户点击更新按钮后在下一个活动中标记出勤后，第二个活动应该完成，并且应该更新第一个活动列表视图。
我成功做了什么： 我已成功标记出勤率并更改列表视图的颜色，但我在关闭第二个活动并重新启动第一个活动后执行了此操作。通过这种方式，listview会因为再次启动活动而更新。
我无法做到的事情： 我希望当用户点击更新按钮时，只有finish（）将调用并且用户返回上一个第一个活动并更新了listview。但是当我这样做时，listview没有得到更新。我必须返回并再次打开活动，然后列表视图会更新，否则不会。我不要那个。我还尝试在第一个活动的onResume方法中通知适配器，这样当用户从第二个活动返回时，第一个活动listview适配器将因onResume方法而更新，但它不起作用。请帮忙
我的Listview活动代码：
public class TeacherWebserviceMainList extends Activity {
int attentedncemarkedCount = 0;
TextView addteacher;
DatabaseHandler databasehandler;
DetailsTeacherwebservice details;
String emis;
ArrayList<DetailsTeacherwebservice> addas = new ArrayList<DetailsTeacherwebservice>();
CustomAdapterTeacherWebservice cusadapter;
ArrayList<DetailsTeacherwebservice> teacherList;
private ListView listcontent = null;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.teacherwebservicemainlist );
addteacher = (TextView) findViewById(R.id.addteachermenu);
databasehandler = new DatabaseHandler(TeacherWebserviceMainList.this);
listcontent = (ListView) findViewById(R.id.teacher_list);
teacherList = databasehandler.teacherwebserviceList(emis);
Rsults();
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == 1) {
if(resultCode == RESULT_OK) {
String update = data.getStringExtra("update");
if(update.equals("1"))
{
//cusadapter.
CustomAdapterTeacherWebservice adapter = new CustomAdapterTeacherWebservice(this, addas);
listcontent.setAdapter(adapter);
}
}
}
}
private void Rsults() {
addas.clear();
//DatabaseHandler databaseHandler=new DatabaseHandler(this);
//ArrayList<ArrayList<Object>> data = databaseHandler.abcTeacherNew();
for (int p = 0; p < teacherList.size(); p++) {
details = new DetailsTeacherwebservice();
//ArrayList<Object> baris = data.get(p);
details.setId(teacherList.get(p).getId());
details.setTeachername(teacherList.get(p).getTeachername());
details.setTeachercnic(teacherList.get(p).getTeachercnic());
details.setTeacherno(teacherList.get(p).getTeacherno());
details.setTeachergender(teacherList.get(p).getTeachergender());
details.setAttendance(teacherList.get(p).getAttendance());
details.setTeacherattendancedetails(teacherList.get(p).getTeacherattendancedetails());
details.setAttendancedatesince(teacherList.get(p).getAttendancedatesince());
details.setAttendancetrasnferschool(teacherList.get(p).getAttendancetrasnferschool());
addas.add(details);
}
cusadapter = new CustomAdapterTeacherWebservice(TeacherWebserviceMainList.this, addas);
listcontent.setAdapter(cusadapter);
listcontent.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
}
});
}
我的列表适配器代码
public class CustomAdapterTeacherWebservice extends BaseAdapter {
private static ArrayList<DetailsTeacherwebservice> searchArrayList;
DatabaseHandler databaseHandler;
private Context context;
private LayoutInflater mInflater;
public CustomAdapterTeacherWebservice(Context context, ArrayList<DetailsTeacherwebservice> results) {
searchArrayList = results;
mInflater = LayoutInflater.from(context);
databaseHandler = new DatabaseHandler(context);
}
@Override
public int getCount() {
return searchArrayList.size();
}
@Override
public Object getItem(int p) {
return searchArrayList.get(p);
}
@Override
public long getItemId(int p) {
return p;
}
public int getViewTypeCount() {
return 500;
}
@Override
public int getItemViewType(int position) {
return position;
}
@Override
public View getView(final int p, View v, ViewGroup parent) {
ViewHolder holder;
context = parent.getContext();
if (v == null) {
v = mInflater
.inflate(R.layout.teacherwebserviceadapter, null);
holder = new ViewHolder();
holder.name = (TextView) v.findViewById(R.id.teacher_name);
holder.cnic = (TextView) v.findViewById(R.id.teacher_cnic);
holder.no = (TextView) v.findViewById(R.id.teacher_phone);
holder.gender = (TextView) v.findViewById(R.id.gender);
holder.status = (TextView) v.findViewById(R.id.status);
holder.info = (ImageView) v.findViewById(R.id.edit);
holder.l1 = (LinearLayout) v.findViewById(R.id.main);
v.setTag(holder);
} else {
holder = (ViewHolder) v.getTag();
}
holder.name.setText(searchArrayList.get(p).getTeachername());
holder.cnic.setText(searchArrayList.get(p).getTeachercnic());
holder.no.setText(searchArrayList.get(p).getTeacherno());
holder.gender.setText(searchArrayList.get(p).getTeachergender());
holder.status.setText(searchArrayList.get(p).getAttendance());
if (searchArrayList.get(p).getAttendance().equals("Absent"))
{
holder.l1.setBackgroundColor(Color.parseColor("#DB674D"));
}
if (searchArrayList.get(p).getAttendance().equals("Present"))
{
holder.l1.setBackgroundColor(Color.parseColor("#7EB674"));
}
if (searchArrayList.get(p).getAttendance().equals("Transfer Out"))
{
holder.l1.setBackgroundColor(Color.parseColor("#FBE87C"));
}
if (searchArrayList.get(p).getAttendance().equals("Resigned"))
{
holder.l1.setBackgroundColor(Color.parseColor("#4FC3F7"));
}
holder.info.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent view_order_intent = new Intent(context, Teacherwebservicemainlistupdate.class);
view_order_intent.putExtra("ID", searchArrayList.get(p).getId());
view_order_intent.putExtra("tname", searchArrayList.get(p).getTeachername());
view_order_intent.putExtra("tgender", searchArrayList.get(p).getTeachergender());
view_order_intent.putExtra("tcnic", searchArrayList.get(p).getTeachercnic());
view_order_intent.putExtra("tno", searchArrayList.get(p).getTeacherno());
view_order_intent.putExtra("tatt", searchArrayList.get(p).getAttendance());
view_order_intent.putExtra("tattdetails", searchArrayList.get(p).getTeacherattendancedetails());
view_order_intent.putExtra("tattdatesince", searchArrayList.get(p).getAttendancedatesince());
view_order_intent.putExtra("tatttrasnferout", searchArrayList.get(p).getAttendancetrasnferschool());
//context.startActivity(view_order_intent);
((Activity)context).startActivityForResult(view_order_intent, 1);
}
});
return v;
}
static class ViewHolder {
TextView name, cnic, no, gender,status;
ImageView info;
LinearLayout l1;
}
此处在适配器代码中单击INFO按钮，然后另一个活动开始，用户可以更新出勤。
这是按下按钮时的更新活动代码：
update.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
DetailsTeacherwebservice schoolinfo = new DetailsTeacherwebservice();
schoolinfo.setTeachername(teachername.getText().toString());
schoolinfo.setTeacherno(teacherno.getText().toString());
schoolinfo.setTeachercnic(teachercnic.getText().toString());
schoolinfo.setTeachergender(teachergender.getText().toString());
schoolinfo.setAttendance(teachergroupstr);
schoolinfo.setTeacherattendancedetails(absentgrpstr);
schoolinfo.setAttendancedatesince(txtDate.getText().toString());
schoolinfo.setAttendancetrasnferschool(transferOutSchool.getText().toString());
databasehandler.updateteacherwebservice(schoolinfo, emis, identity);
Toast.makeText(Teacherwebservicemainlistupdate.this, "Updated Successfully", Toast.LENGTH_SHORT).show();
Intent intent = new Intent();
intent.putExtra("update", "1");
setResult(RESULT_OK, intent);
finish();
}
}
});
我可以在单击更新按钮时再次启动listview活动，但会更改单击列表项的索引，即因为活动再次启动。我想要的是如果我点击第10个项目然后当下一个活动打开并且用户更新出勤时它返回到相同索引位置的上一个活动，这样用户就不必再次滚动回到第10个项目< / p>
答案 0 :(得分：2)
为列表项添加此代码点击：
Intent intent = new Intent();
intent.putExtra("update", "1");
intent.putExtra("position",getIntent().getIntExtra("position",0));
setResult(RESULT_OK, intent);
finish();
在更新按钮中添加此代码：
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == 1) {
if(resultCode == RESULT_OK) {
String update = data.getStringExtra("update");
if(update.equals("1"))
{
// add your code to update list view
teacherList = databasehandler.teacherwebserviceList(emis);
Rsults();
YourAdapterClassName adapter = new YourAdapterClassName(this, arrList);
listView.setAdapter(adapter);
listView.smoothScrollToPosition(getIntent().getIntExtra("position",0));
}
}
}
}
当您从活动返回到实现列表视图的活动时，此方法称为：
$('#third').position().top答案 1 :(得分：1)
以下是两个示例，第一个示例，其中ListView的源是List（在本例中使用自定义适配器），第二个是源是Cursor（使用SimpleCursorAdapter）
许多人陷入的陷阱只是使用以下内容更新List： -
myList = method();
myAdapter.notifyDataSetChanged();
猜测，那是你陷入的陷阱。
当应该做的是使用List的方法来改变它（例如clear，add，addAll，remove）。
我相信this explains the reasoning - Is Java “pass-by-reference” or “pass-by-value”?
/**
* Build or rebuild the List of TaskData's, instantiate the
* Custom Array Adapter if needed and also notify the adapter
* if the List may have been changed.
*/
private void prepTasksCustomArrayList() {
// Determine if the adpater needs to be notified of changes
boolean notify_dataset_changed = (mCsr != null && mCustomArrayAdapter != null);
// If the List is not null then assume that it has changed
// otherwise just get the List
if (mTasks != null) {
mTasks.clear();
mTasks.addAll(dbhlpr.getAllTasks());
} else {
mTasks = dbhlpr.getAllTasks();
}
// If the adapter is null then instantiate it
if (mCustomArrayAdapter == null) {
mCustomArrayAdapter = new CustomArrayAdapter(
this,
R.layout.taskdata_item,
mTasks);
}
// Notify the adapter that the List has changed
if (notify_dataset_changed) {
mCustomArrayAdapter.notifyDataSetChanged();
}
}
备注
ListView。mTaskList = this.findViewById(R.id.tasklist); // The ListView prepTasksCustomArrayList() mTaskList.setAdapter(mCustomArrayAdapter) onresume只是（与onCreate中的3行相同）prepTasksCustomArrayList() onCreate中看到正在设置适配器。mTasks.addAll(dbhlpr.getAllTasks());是获取源数据的原因。/**
* Build or rebuild the List via Cursor using the bespoke layout
*/
private void prepCursorListBespoke() {
boolean swapcursor = (mCsr != null && mCursorAdapter2 != null);
if (mCursorAdapter2 == null) {
mCursorAdapter2 = new SimpleCursorAdapter(this,R.layout.taskdata_item,mCsr,
new String[]{ Datasource.TASKS_ID_COL,
Datasource.TASKS_TYPE_COL,
Datasource.TASKS_NAME_COL,
Datasource.TASKS_OWNER_COL,
Datasource.TASKS_EXPIRATION_COL},
new int[]{R.id.task_id,
R.id.task_type,
R.id.task_name,
R.id.task_owner,
R.id.task_expiration},
0);
}
if (swapcursor) {
mCursorAdapter2.swapCursor(mCsr);
}
}
备注
prepCursorListBespoke代替notifyDataSetChanged
swapCursor因为它更具描述性。 swapCursor作为游标。以下更改可能有效，粗略地说我已经应用了上面的List示例。
即。 swapCursor（已添加）调用Rsults，它将通知适配器数据已更改。
代码尚未经过测试，因为代码不足。 （onResume类没有代码，b）DatabaseHandler类没有代码。因此可能存在错误。
查看DetailsTeacherwebservice评论后应该说明已完成/更改的内容。
//++++++++++++++...答案 2 :(得分：0)
//你必须在onResume方法
中的适配器中设置数据 @Override
protected void onResume() {
super.onResume();
}
答案 3 :(得分：0)
在这种情况下你可以使用eventbus：
这是一个例子：
在build.gradle文件中
compile 'org.greenrobot:eventbus:3.0.0'
在活动中有listview：
@Override
public void onStart() {
super.onStart();
EventBus.getDefault().register(this); // register event
}
@Override
public void onStop() {
super.onStop();
EventBus.getDefault().unregister(this); // unregister event
}
@Subscribe(threadMode = ThreadMode.MAIN)
public void onEvent(EventBusInfo eventBusInfo) {
if (eventBusInfo.getProcessId() == 99) {
// eventBusInfo.getData();
notifyDataSetChanged();
}
}
在更新活动中
yourButtonFinish.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
finish();
EventBusInfo event = new EventBusInfo();
event.setProcessId(99);
//event.setData(object) //if you want get data back
EventBus.getDefault().post(event);
}
});
类EventBusInfo
public class EventBusInfo {
private int processId;
private Object data;
public EventBusInfo(int processId, Object data) {
this.processId = processId;
this.data = data;
}
public EventBusInfo() {
}
public EventBusInfo(int processId) {
this.processId = processId;
}
public Object getData() {
return data;
}
public void setData(Object data) {
this.data = data;
}
public int getProcessId() {
return processId;
}
public void setProcessId(int processId) {
this.processId = processId;
}
}
答案 4 :(得分：0)
保存每次更改中的列表项，然后使用intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP)重新启动适配器的Activity以关闭旧的ListView。
是我所做的，并且效果很好。
如果列表不为空，那么我将使用适配器重新启动活动，并且有一个新的ListView关闭前一个。或者，如果它为空，那么我将启动另一个活动（没有空的ListView）
每次使用Gson将列表项保存并加载到SharedPreferences
由于某种原因，notifyDataSetChanged()在我的情况下效果不佳，因此我更喜欢这种解决方案。