[英]Android Baseadapter to populate ListView
我正在學習Android，想用用戶的名稱和電子郵件填充Listview 。 名稱和電子郵件存儲在sqlite表中。 我正在使用baseadapter將數據綁定到我的視圖。
這是我的代碼：
public class Contact {
int _id;
String _name;
String _email;
String _phone_number;
String _password;
public Contact () {
}
public Contact (int id, String name, String phone_number, String email, String password) {
this._id = id;
this._name = name;
this._email = email;
this._phone_number = phone_number;
this._password = password;
}
public Contact (String name, String phone_number, String email, String password ){
this._name = name;
this._phone_number = phone_number;
this._email = email;
this._password = password;
}
// GETTERS AND SETTERS
}
public class CustomAdapter extends BaseAdapter {
private static LayoutInflater inflater=null;
//Context context;
ArrayList list;
Contact contact;
public CustomAdapter (Context context, ArrayList lists) {
this.list = lists;
inflater = LayoutInflater.from(context);
}
@Override
public int getCount() {
int length = list.size();
return length;
}
@Override
public Object getItem(int position) {
return list.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if (convertView == null) {
convertView = inflater.inflate(R.layout.custom_list_view,null);
}
contact = null;
contact = (Contact) list.get(position);
TextView name = (TextView) convertView.findViewById(R.id.user_names);
name.setText(contact.get_name());
TextView email = (TextView) convertView.findViewById(R.id.user_emails);
email.setText(contact.get_email());
TextView phone = (TextView) convertView.findViewById(R.id.user_phones);
phone.setText(contact.get_phone_number());
return convertView;
}
}
這里列表的大小= 4
0 = Manish
1 = manish.com
2 = John
3 = john.com
但在網上：
contact = (Contact) list.get(position);
the cast class exception is thrown
該列表應顯示如下：
Manish
Manish.com
John
John.com
XYZ
XYZ.com
感謝您的幫助。 日志貓：
FATAL EXCEPTION: main
Process: com.example.manish.userdetail, PID: 21749
java.lang.ClassCastException: java.lang.String cannot be cast to com.example.manish.userdetail.Contact
at com.example.manish.userdetail.CustomAdapter.getView(CustomAdapter.java:67)
at android.widget.AbsListView.obtainView(AbsListView.java:2255)
at android.widget.ListView.makeAndAddView(ListView.java:1790)
at android.widget.ListView.fillDown(ListView.java:691)
at android.widget.ListView.fillFromTop(ListView.java:752)
at android.widget.ListView.layoutChildren(ListView.java:1630)
at android.widget.AbsListView.onLayout(AbsListView.java:2087)
at android.view.View.layout(View.java:14860)
at android.view.ViewGroup.layout(ViewGroup.java:4643)
at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1055)
at android.view.View.layout(View.java:14860)
at android.view.ViewGroup.layout(ViewGroup.java:4643)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1671)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1525)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1434)
at android.view.View.layout(View.java:14860)
at android.view.ViewGroup.layout(ViewGroup.java:4643)
at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1055)
at android.view.View.layout(View.java:14860)
at android.view.ViewGroup.layout(ViewGroup.java:4643)
at android.support.design.widget.CoordinatorLayout.layoutChild(CoordinatorLayout.java:1037)
at android.support.design.widget.CoordinatorLayout.onLayoutChild(CoordinatorLayout.java:747)
at android.support.design.widget.ViewOffsetBehavior.onLayoutChild(ViewOffsetBehavior.java:42)
at android.support.design.widget.AppBarLayout$ScrollingViewBehavior.onLayoutChild(AppBarLayout.java:1156)
at android.support.design.widget.CoordinatorLayout.onLayout(CoordinatorLayout.java:760)
at android.view.View.layout(View.java:14860)
at android.view.ViewGroup.layout(ViewGroup.java:4643)
at android.support.v4.widget.DrawerLayout.onLayout(DrawerLayout.java:1043)
at android.view.View.layout(View.java:14860)
at android.view.ViewGroup.layout(ViewGroup.java:4643)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453)
at android.widget.FrameLayout.onLayout(FrameLayout.java:388)
at android.view.View.layout(View.java:14860)
at android.view.ViewGroup.layout(ViewGroup.java:4643)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1671)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1525)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1434)
at android.view.View.layout(View.java:14860)
at android.view.ViewGroup.layout(ViewGroup.java:4643)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453)
at android.widget.FrameLayout.onLayout(FrameLayout.java:388)
at android.view.View.layout(View.java:14860)
at android.view.ViewGroup.layout(ViewGroup.java:4643)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1671)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1525)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1434)
at android.view.View.layout(View.java:14860)
at android.view.ViewGroup.layout(ViewGroup.java:4643)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453)
at android.widget.FrameLayout.onLayout(FrameLayout.java:388)
at android.view.View.layout(View.java:14860)
at android.view.ViewGroup.layout(ViewGroup.java:4643)
at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2013)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1770)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1019)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5725)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
at android.view.Choreographer.doCallbacks(Choreographer.java:574)
at android.view.Choreographer.doFrame(Choreographer.java:544)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
at android.os.Handler.handleCallback(Handler.java:73
這就是您的CustomAdapter類的外觀
class CustomAdapter extends BaseAdapter {
private static LayoutInflater inflater = null;
ArrayList<Contact> list;
public CustomAdapter(Context context, ArrayList<Contact> lists) {
this.list = lists;
inflater = LayoutInflater.from(context);
}
@Override
public int getCount() {
return list.size();
}
@Override
public Object getItem(int position) {
return list.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if (convertView == null) {
convertView = inflater.inflate(R.layout.custom_list_view, parent, false);
holder = new ViewHolder(convertView);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.name.setText(list.get(position).get_name());
holder.email.setText(list.get(position).get_email());
holder.phone.setText(list.get(position).get_phone_number());
return convertView;
}
private static class ViewHolder {
TextView name, email, phone;
ViewHolder(View covertView) {
name = (TextView) covertView.findViewById(R.id.user_names);
email = (TextView) covertView.findViewById(R.id.user_emails);
phone = (TextView) covertView.findViewById(R.id.user_phones);
}
}
}
如下所示添加靜態ViewHolder類，並按如下所示修改您的getView()方法：
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if (convertView == null) {
convertView = inflater.inflate(R.layout.custom_list_view,null);
holder.name = (TextView) convertView.findViewById(R.id.user_names);
holder.email = (TextView) convertView.findViewById(R.id.user_emails);
holder.phone = (TextView) convertView.findViewById(R.id.user_phones);
}
else {
holder = (ViewHolder) convertView.getTag();
}
name.setText(list.get(/*position of name cell*/));
email.setText(list.get(/*position of email cell*/));
phone.setText(list.get(/*position of phone cell*/));
}
private static class ViewHolder {
TextView name;
TextView email;
TextView phone;
}
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