getCheckedItemPositions（）总是返回null（Android的ListView控件） [英] getCheckedItemPositions() always returning null (Android ListView)

问题描述

编辑：基于问题的演变，我编辑了这个问题。

所有的

首先，我知道有一些类似的问题，但他们每个人都有特定的差异，这使得答案没用，我...

我是真的真的AP preciate如果有人能帮助我，我变得非常绝望了这个问题...

所以，问题是：我想填充复选框一个ListView，并且不能使用simple_multiple_choice_mode（类似的东西），因为我需要手动建立我的XML布局 - 所以我使用的list_item.xml文件：

 ＆LT; XML版本=1.0编码=UTF-8＆GT？;
        ＆LT;复选框
的xmlns：机器人=htt​​p://schemas.android.com/apk/res/android机器人：以下属性来=8毫米
机器人：layout_width =FILL_PARENT
        机器人：layout_height =WRAP_CONTENT机器人：ID =@ + ID / nomeAPP的风格=？的listItem＆GT;
        ＆LT; /复选框＆GT;
 

但问题是，如果我使用simple_multiple（..）模式选项，getCheckedItemPositions工作正常。如果没有（因为我有下面的code）getCheckedItemPositions来空。所以，从我读，这是一个常见的​​错误，这需要一个处理程序解决方法。但我不能让处理器的工作，我在logcat中得到一个例外，显示java.lang.NullPointerException。

谁能帮帮我吗？

我这个小pretty的code：

  this.setListAdapter（新ArrayAdapter＆LT;字符串＆GT;（这一点，
                    R.layout.list_item，AUX））;

            list.setItemsCanFocus（假）;
            list.setChoiceMode（ListView.CHOICE_MODE_MULTIPLE）;
            list.setSelected（真正的）;
            list.setClickable（真正的）;
            list.setOnItemSelectedListener（新OnItemSelectedListener（）{
                公共无效onItemSelected（适配器视图＆LT;＆GT;为arg0，查看ARG1，
                        INT ARG2，长ARG3）{
                    //自动生成方法存根

                    Log.d（检查，+ ARG2）;


                }

                公共无效onNothingSelected（适配器视图＆LT;＆GT;为arg0）{
                    //自动生成方法存根
                }

            }）;


            复选框C =（复选框）findViewById（R.id.nomeAPP）;
            c.setOnCheckedChangeListener（新OnCheckedChangeListener（）{
                公共无效onCheckedChanged（CompoundButton为arg0，布尔ARG1）{
                    复选框复选框=（复选框）为arg0;
                    布尔器isChecked = checkbox.isChecked（）;

                    如果（==器isChecked真）
                        Log.v（TAG，真）;
                    其他
                        Log.v（TAG，假）;
                }
            }）;
 

解决方案

看起来这是在使用setAdapter的，这是使用setListAdapter解决的问题。

让我们来看看，文档指出ListActivity应该使用

 名单= getListView（）;
＆LT; ListView的机器人：ID =@机器人：ID /列表
 

所以，不要担心=+ @ ID（....

现在，我们可以在我们的活动知道去哪里的名单，现在我们可以使用

  setListAdapter（新ArrayAdapter＆LT;字符串＆GT;（这一点，
                      R.Layout.List_item，AUX））;
 

和一切工作正常。

EDIT: Based on evolution of the problem, I edited this question.

First of all, I know there some similar questions, but each one of them has a specific difference, that makes the answer useless for me...

I really really appreciate if anyone can help me, I'm getting really desperate with this problem...

So the problem is: I want to populate a ListView with checkboxes, and can't use simple_multiple_choice_mode (something like that) because I need to manually build my XML layout - so I'm using the list_item.xml file:

<?xml version="1.0" encoding="utf-8"?>
        <CheckBox 
xmlns:android="http://schemas.android.com/apk/res/android" android:paddingLeft="8mm"
android:layout_width="fill_parent"
        android:layout_height="wrap_content" android:id="@+id/nomeAPP" style="?listItem">
        </CheckBox>

Problem is, if I use the simple_multiple (..) mode option, getCheckedItemPositions works fine. If don't (as I have in the code below) getCheckedItemPositions comes null. So from what I read, it's a common bug, that needs an handler as workaround. But I cant get the handler to work, I get an exception with java.lang.NullPointerException in the logcat.

Can anyone please help me?

I have this little pretty code:

this.setListAdapter(new ArrayAdapter<String>(this, 
                    R.layout.list_item, aux));

            list.setItemsCanFocus(false);
            list.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
            list.setSelected(true);
            list.setClickable(true);
            list.setOnItemSelectedListener(new OnItemSelectedListener() {
                public void onItemSelected(AdapterView<?> arg0, View arg1,
                        int arg2, long arg3) {
                    //  Auto-generated method stub

                    Log.d("checked",""+arg2);        


                }

                public void onNothingSelected(AdapterView<?> arg0) {
                    // Auto-generated method stub
                }

            });


            CheckBox c = (CheckBox) findViewById(R.id.nomeAPP);
            c.setOnCheckedChangeListener(new OnCheckedChangeListener() {
                public void onCheckedChanged(CompoundButton arg0, boolean arg1) {
                    CheckBox checkbox = (CheckBox)arg0; 
                    boolean isChecked = checkbox.isChecked();

                    if(isChecked == true)
                        Log.v("TAG", "true");
                    else
                        Log.v("TAG", "false");
                }
            });

解决方案

Looks that was a bug in the use of setAdapter, which is solved using setListAdapter.

Let's see, documentation states that ListActivity should use

list=getListView();
<ListView android:id="@android:id/list"

so forget about = "+@id(....

now we can our activity knows "where" is the List and now we can use

setListAdapter(new ArrayAdapter<String>(this, 
                      R.Layout.List_item, aux));

and everything works fine.

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