我正在尝试为Android应用程序创建自定义首选项，以限制用户可以选择的项目数。达到限制后，应禁用未选择的项目，并且仅启用当前选定的项目。如果选择的项目少于限制，则应启用所有项目。
这是我拼凑在一起的两个班级。代码运行正常，但没有检查CheckedTextView。结果没有维持状态。
首先是视图类......
import android.content.Context;
import android.os.Bundle;
import android.os.Parcelable;
import android.util.AttributeSet;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.CheckedTextView;
import android.widget.ListView;
public class LimitedMultiChoiceView extends ListView
implements AdapterView.OnItemClickListener
{
private static final String SEPARATOR = "OV=I=XseparatorX=I=VO";
private static final String LIMITEDSELECTION="limitedSelection";
private static final String SUPERSTATE="superState";
private String mSelection = "";
public LimitedMultiChoiceView(Context context, CharSequence[] items, int limit)
{
this(context, null, 0, items, limit);
} // LimitedMultiChoiceView(Context context)
public LimitedMultiChoiceView(Context context, AttributeSet attrs, CharSequence[] items, int limit)
{
this(context, attrs, 0, items, limit);
} // LimitedMultiChoiceView(Context context, AttributeSet attrs)
public LimitedMultiChoiceView(Context context, AttributeSet attrs
, int defStyle, CharSequence[] items, int limit)
{
super(context, attrs, defStyle);
setAdapter(new ItemAdapter(context, android.R.layout.simple_list_item_multiple_choice, items, limit));
} // LimitedMultiChoiceView(Context context, AttributeSet attrs, int defStyle)
public String getSelection()
{
return mSelection;
} // String getSelection()
public void onItemClick(AdapterView<?> parent, View child, int position, long id)
{
// For now we don't need anything...
// we think the ItemAdapter manages what we need for each item.
} // void onItemClick(AdapterView<?> parent, View child, int position, long id)
@Override
public void onRestoreInstanceState(Parcelable toParce)
{
Bundle state=(Bundle)toParce;
super.onRestoreInstanceState(state.getParcelable(SUPERSTATE));
mSelection = state.getString(LIMITEDSELECTION);
} // void onRestoreInstanceState(Parcelable toParce)
@Override
public Parcelable onSaveInstanceState()
{
Bundle state=new Bundle();
state.putParcelable(SUPERSTATE, super.onSaveInstanceState());
state.putString(LIMITEDSELECTION, mSelection);
return(state);
} // Parcelable onSaveInstanceState()
public void setSelection(String value)
{
mSelection = value;
} // void setSelection(String value)
class ItemAdapter extends ArrayAdapter<CharSequence>
{
CharSequence[] mItems = null;
int mLimit = 1;
public ItemAdapter(Context context, int viewResId, CharSequence[] items, int limit)
{
super(context, viewResId, items);
mItems = items;
mLimit = limit;
} // ItemAdapter(Context context, int viewResId, CharSequence[] strings, int limit)
public boolean areAllItemsEnabled()
{
// Since we are in a limited selection list not all items can be
// selected so this always returns false, there is no calculating
// to do.
return false;
} // boolean areAllItemsEnabled()
public boolean isEnabled(int position)
{
boolean[] clickedIndexes = new boolean[this.getCount()];
boolean result = false;
int selectedCount = 0;
mSelection = "";
for (int item=0; item < clickedIndexes.length; item++ )
{
View itemView = this.getView(item, null, LimitedMultiChoiceView.this);
if (itemView instanceof CheckedTextView)
{
CheckedTextView check = (CheckedTextView)itemView;
// First we turn the check mark on or off...
if (item == position)
{
check.setChecked(!check.isChecked());
} // (item == position)
// Now we count how many are checked and mark our tracking array
if (check.isChecked())
{
clickedIndexes[item] = true;
mSelection += check.getText() + SEPARATOR;
}
else
{
clickedIndexes[item] = false;
} // (check.isChecked())
} // (itemView instanceof CheckedTextView)
if (clickedIndexes[item])
selectedCount++;
} // (int item=0; item< clickedIndexes.length; item++ )
if (selectedCount >= mLimit)
{
if (clickedIndexes[position])
{
result = true;
}
else
{
result = false;
} // (clickedIndexes[position])
}
else
{
result = true;
} // (selectedCount >= mLimit)
return result;
} // boolean isEnabled(int position)
} // class ItemAdapter extends ArrayAdapter<CharSequence>
} // class LimitedMultiChoiceView extends ListView
这是偏好类......
import android.content.Context;
import android.preference.ListPreference;
import android.util.AttributeSet;
import android.view.View;
public class ListPreferenceLimitedMultiSelect extends ListPreference
{
int mLimit = 3;
LimitedMultiChoiceView mList = null;
String mSelection = "";
public ListPreferenceLimitedMultiSelect(Context context)
{
this(context, null);
} // ListPreferenceLimitedMultiSelect(Context context)
public ListPreferenceLimitedMultiSelect(Context context, AttributeSet attr)
{
super(context, attr);
} // ListPreferenceLimitedMultiSelect(Context context, AttributeSet attr)
@Override
protected void onBindDialogView(View v)
{
super.onBindDialogView(v);
mList.setSelection(mSelection);
} // void onBindDialogView(View v)
@Override
protected View onCreateDialogView()
{
mList = new LimitedMultiChoiceView(getContext()
, this.getEntries(), mLimit);
return(mList);
} // View onCreateDialogView()
@Override
protected void onDialogClosed(boolean positiveResult)
{
super.onDialogClosed(positiveResult);
if (positiveResult)
{
if (callChangeListener(mList.getSelection()))
{
mSelection = mList.getSelection();
persistString(mSelection);
} // (callChangeListener(mList.getSelection()))
} // (positiveResult)
} // void onDialogClosed(boolean positiveResult)
@Override
protected void onSetInitialValue(boolean restoreValue, Object defaultValue)
{
mSelection =(restoreValue ? getPersistedString(mSelection) : (String)"");
} // void onSetInitialValue(boolean restoreValue, Object defaultValue)
} // class ListPreferenceLimitedMultiSelect extends ListPreference
谢谢，
\ ^ /我l