如何在编辑列表视图项目时使用自定义适配器？
如何在编辑列表视图项目时使用自定义适配器？
提问于 2013-11-11 22:43:32
我有两个活动。一个是主活动(一个添加按钮和一个列表视图)，另一个是任务名称的edittext，日期的datepicker，任务优先级的微调器。当ı启动此应用程序时，它会显示添加按钮，当ı单击此按钮时，它会显示编辑文本、日期选择器和微调器，当ı填充这些字段并单击确定按钮时，它会将此添加到mainactivity的列表视图中。我的代码提供了向listview添加新项的功能，但我对如何编辑这些项感到困惑。当我单击listview中的某一项时，ı想要创建新的编辑活动(此活动还必须有一个edittext、微调器、datepicker和来自用户的输入值)。此活动更新/编辑mainactivity的listview中的项。在我的代码中，当我单击listview中的一个项目时，我得到一个错误，如下所示：
LogCat：
11-11 16:47:38.311: E/AndroidRuntime(1015): FATAL EXCEPTION: main
11-11 16:47:38.311: E/AndroidRuntime(1015): java.lang.ClassCastException: android.widget.Spinner cannot be cast to android.widget.TextView
11-11 16:47:38.311: E/AndroidRuntime(1015): at com.example.enhancedtodolistapplication.ToDoItemAdapter.getView(ToDoItemAdapter.java:52)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.widget.AbsListView.obtainView(AbsListView.java:2177)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.widget.ListView.measureHeightOfChildren(ListView.java:1247)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.widget.ListView.onMeasure(ListView.java:1159)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.view.View.measure(View.java:15848)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5008)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.view.View.measure(View.java:15848)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5008)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.view.View.measure(View.java:15848)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5008)
11-11 16:47:38.311: E/AndroidRuntime(1015): at com.android.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:302)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.view.View.measure(View.java:15848)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5008)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
11-11 16:47:38.311: E/AndroidRuntime(1015): at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2189)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.view.View.measure(View.java:15848)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1905)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1104)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1284)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1004)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5481)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.view.Choreographer.doCallbacks(Choreographer.java:562)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.view.Choreographer.doFrame(Choreographer.java:532)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.os.Handler.handleCallback(Handler.java:730)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.os.Handler.dispatchMessage(Handler.java:92)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.os.Looper.loop(Looper.java:137)
11-11 16:47:38.311: E/AndroidRuntime(1015): at android.app.ActivityThread.main(ActivityThread.java:5103)
11-11 16:47:38.311: E/AndroidRuntime(1015): at java.lang.reflect.Method.invokeNative(Native Method)
11-11 16:47:38.311: E/AndroidRuntime(1015): at java.lang.reflect.Method.invoke(Method.java:525)
11-11 16:47:38.311: E/AndroidRuntime(1015): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
11-11 16:47:38.311: E/AndroidRuntime(1015): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
11-11 16:47:38.311: E/AndroidRuntime(1015): at dalvik.system.NativeStart.main(Native Method)下面是我的代码：
AddActivity.java
public class AddActivity extends Activity{
private String[] states;
private Spinner spinner;
int position1;
String priority;
EditText etDate;
Button change_date;
final int Date_Dialog_ID=0;
int cDay,cMonth,cYear; // this is the instances of the current date
Calendar cDate;
int sDay,sMonth,sYear; // this is the instances of the entered date
protected static final String tasks = "addingTask";
private static final String LOG_TAG = "addingTaskActivity";
MainActivity main;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
initUI();
showDatePicker();
showPriorityLevel();
}
private void showPriorityLevel() {
// TODO Auto-generated method stub
states = getResources().getStringArray(R.array.priority_level);
spinner = (Spinner) findViewById(R.id.priority_spinner);
ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this,
android.R.layout.simple_spinner_item, states);
dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(dataAdapter);
spinner.setOnItemSelectedListener(new OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View view,
int position, long id) {
position1 = spinner.getSelectedItemPosition();
switch(position1)
{
case 0: priority = "0";
break;
case 1: priority = "1";
break;
case 2: priority = "2";
break;
case 3: priority = "3";
break;
case 4: priority = "4";
break;
case 5: priority = "5";
break;
case 6: priority = "6";
break;
case 7: priority = "7";
break;
case 8: priority = "8";
break;
case 9: priority = "9";
break;
default: break;
}
}
@Override
public void onNothingSelected(AdapterView<?> arg0) {
}
});
}
private void showDatePicker() {
// TODO Auto-generated method stub
etDate=(EditText)findViewById(R.id.EditText01);
change_date=(Button)findViewById(R.id.Button01);
change_date.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
//triggers the DatePickerDialog
showDialog(Date_Dialog_ID);
}
});
//getting current date
cDate=Calendar.getInstance();
cDay=cDate.get(Calendar.DAY_OF_MONTH);
cMonth=cDate.get(Calendar.MONTH);
cYear=cDate.get(Calendar.YEAR);
//assigning the edittext with the current date in the beginning
sDay=cDay;
sMonth=cMonth;
sYear=cYear;
updateDateDisplay(sYear,sMonth,sDay);
}
@Override
protected Dialog onCreateDialog(int id) {
switch (id) {
case Date_Dialog_ID:
return new DatePickerDialog(this, onDateSet, cYear, cMonth,
cDay);
}
return null;
}
private void updateDateDisplay(int year,int month,int date) {
// TODO Auto-generated method stub
etDate.setText(date+"-"+(month+1)+"-"+year);
}
private OnDateSetListener onDateSet=new OnDateSetListener() {
@Override
public void onDateSet(DatePicker view, int year, int monthOfYear,
int dayOfMonth) {
// TODO Auto-generated method stub
sYear=year;
sMonth=monthOfYear;
sDay=dayOfMonth;
updateDateDisplay(sYear,sMonth,sDay);
}
};
private void initUI() {
// TODO Auto-generated method stub
setContentView(R.layout.adding_task);
final EditText editTextTask = (EditText) findViewById(R.id.edit_text_task);
Button OKbutton = (Button) findViewById(R.id.ok_Button);
final EditText editTextDate = (EditText) findViewById(R.id.EditText01);
OKbutton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
ArrayList<String> addedDatas = new ArrayList<String>();
String addingTask = editTextTask.getText().toString();
String deadline = editTextDate.getText().toString();
//String concatenate = priority + " " + addingTask + " " + deadline;
Intent myIntent = new Intent();
addedDatas.add(addingTask);
addedDatas.add(deadline);
addedDatas.add(priority);
myIntent.putExtra("addingTask", addedDatas);
setResult(Activity.RESULT_OK, myIntent);
finish();
}
});
}}
MainActivity.java
public class MainActivity extends Activity {
protected static final String edits = "mainTask";
private ArrayAdapter<String> listAdapter;
//private ToDoItemAdapter myCustomAdapter;
private ArrayList<String> listString;
public ArrayList<ToDoItem> listItems;
public static final int ADD_TASKS = 1;
public static final int EDIT_TASKS = 2;
Button button;
ListView listView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initUI();
setListener();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
private void initUI() {
getViewReferences();
initializeToDoList();
}
private void setListener() {
// TODO Auto-generated method stub
button.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Intent addTaskIntent = new Intent(MainActivity.this, AddActivity.class);
startActivityForResult(addTaskIntent, ADD_TASKS);
}
});
listView.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
// TODO Auto-generated method stub
System.out.println(arg2);
ToDoItemAdapter myAdapter = new ToDoItemAdapter(MainActivity.this,R.layout.editing_task,listItems);
listView.setAdapter(myAdapter);
Intent editTaskIntent = new Intent(MainActivity.this, EditingTask.class);
//editTaskIntent.putExtra("mainTask", arg2);
startActivityForResult(editTaskIntent, EDIT_TASKS);
}
});
}
private void getViewReferences() {
// TODO Auto-generated method stub
button = (Button) findViewById(R.id.addButton);
listView = (ListView) findViewById(R.id.listView);
}
@SuppressWarnings({ "unchecked", "rawtypes" })
private void initializeToDoList() {
// TODO Auto-generated method stub
listItems = new ArrayList<ToDoItem>();
listString = new ArrayList<String>();
listAdapter = new ArrayAdapter(this, android.R.layout.simple_list_item_1, listString);
listView.setAdapter(listAdapter);
View noTaskView = findViewById(R.id.emptyToDoList);
listView.setEmptyView(noTaskView);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
// TODO Auto-generated method stub
if (resultCode == Activity.RESULT_OK) {
switch (requestCode) {
case ADD_TASKS:
updateToDoList(data);
break;
case EDIT_TASKS:
break;
default:
break;
}
}
super.onActivityResult(requestCode, resultCode, data);
}
private void updateToDoList(Intent data) {
// TODO Auto-generated method stub
String task = AddActivity.tasks;
ArrayList<String> list = data.getStringArrayListExtra(task);
String addedTask = list.get(0);
String addedDeadline = list.get(1);
String addedPriority = list.get(2);
ToDoItem item = new ToDoItem(addedTask, addedDeadline ,"0", addedPriority);
listItems.add(item);
listString.add(addedTask + " " + addedDeadline + " " + addedPriority);
Log.w("Items:",listItems.get(0).getTask());
Log.w("String:",listString.get(0));
listAdapter.notifyDataSetChanged();
}}
ToDoItemAdapter.java
公共类ToDoItemAdapter扩展了ArrayAdapter {
private int resource;
public ToDoItemAdapter(Context context, int resource, ArrayList<ToDoItem> objects) {
super(context, resource, objects); // TODO Auto-generated constructor stub
this.resource = resource;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
LinearLayout todoView;
ToDoItem todo = getItem(position);
String taskString = todo.getTask();
String dateString = todo.getDeadline();
String priorityString = todo.getPriority();
if (convertView == null)
{
todoView = new LinearLayout(getContext());
String inflater = Context.LAYOUT_INFLATER_SERVICE;
LayoutInflater li;
li = (LayoutInflater)getContext().getSystemService(inflater);
li.inflate(resource, todoView, true);
}
else
{
todoView = (LinearLayout) convertView;
}
TextView taskView = (TextView) todoView.findViewById(R.id.edit_text_task2);
TextView dateView = (TextView) todoView.findViewById(R.id.EditText02);
TextView priorityView = (TextView) todoView.findViewById(R.id.priority_spinner2);
taskView.setText(taskString);
dateView.setText(dateString);
priorityView.setText(priorityString);
return todoView;
} }
ToDoItem.java
public class ToDoItem {
String task;
String deadline;
String status;
String priority;
public ToDoItem(String task, String deadline, String status, String priority) {
super();
this.task = task;
this.deadline = deadline;
this.status = status;
this.priority = priority;
}
public String getTask() {
return task;
}
public String getDeadline() {
return deadline;
}
public String getStatus() {
return status;
}
public String getPriority() {
return priority;
}
@Override
public String toString() {
return priority + " " + task + " " + deadline + " " + status;
}}
最后，我有一个EditingTask.java类，我不知道如何与我的自定义适配器相结合……
提前谢谢你。
回答 2
Stack Overflow用户
发布于 2013-11-11 22:49:54
要使ArrayAdapter除了在可更新的列表中显示TextViews之外还能做任何事情，您必须将其子类化。下面是你如何做到这一点的一个例子。
在getView方法中，您可以修改项的视图并设置侦听器。
public class CustomAdapter extends ArrayAdapter<String>
{
private LayoutInflater inflater;
private int resourceId;
private List<String> data;
public CustomAdapter(Context context, int resourceId, List<String> data)
{
super(context, resourceId, data);
inflater = LayoutInflater.from(context);
this.resourceId = resourceId;
this.data = data;
}
@Override
public View getView(int position, View view, ViewGroup parent)
{
if (view == null)
view = inflater.inflate(resourceId, null);
String data_item = (String) ((ListView) parent).getItemAtPosition(position);
CheckBox checkBox = ((CheckBox) view.findViewById(R.id.check_box));
// Do your thing
return view;
}
}Stack Overflow用户
发布于 2013-11-11 23:18:11
要获得被点击的元素，你应该使用OnItemClickListener。下面是一个例子：
list.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view,
int position, long id) {
MyAdapter adapter = (MyAdapter) list.getAdapter();
String name = adapter.getItem(position).getName();
Intent intent = new Intent(MainActivity.this, DetailActivity.class);
intent.putExtra("name", name);
MainActivity.this.startActivity(intent);
}
});页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/19909039
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