Question

Hy家伙我正在开发一个Android应用程序，它进展顺利，但我现在卡住了。我试图在点击listview项目时调用活动，它必须根据listview项目详细信息的详细信息打开一个特定的活动。这是我在方法中的代码。

private void updateList() {
    // For a ListActivity we need to set the List Adapter, and in order to do
    //that, we need to create a ListAdapter.  This SimpleAdapter,
    //will utilize our updated Hashmapped ArrayList, 
    //use our single_post xml template for each item in our list,
    //and place the appropriate info from the list to the
    //correct GUI id.  Order is important here.
    ListAdapter adapter = new SimpleAdapter(this, mOutletsList,
    R.layout.single_outlet, new String[] { TAG_OUTLET_NAME,     TAG_SPARKLING_CHANNEL, 

TAG_SPARKLING_CLASSIFICATION, TAG_CLASS}, new int[]
                    { R.id.outlet_name,     R.id.sparkling_channel, R.id.sparkling_classification, 

 R.id.cls_state});

    // I shouldn't have to comment on this one:
    setListAdapter(adapter);

    // Optional: when the user clicks a list item we 
    //could do something.  However, we will choose
    //to do nothing...
    final ListView lv = getListView();  
    lv.setOnItemClickListener(new OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> parent, View view,
                int position, long id) {


            HashMap<String, String>map = (HashMap<String, String>)parent.getItemAtPosition(position);


            String foutname = map.get(TAG_OUTLET_NAME);
            String fchannel = map.get(TAG_SPARKLING_CHANNEL);
            String fclass = map.get(TAG_SPARKLING_CLASSIFICATION);
            String fclass_state = map.get(TAG_CLASS);

            String compr = "GDB";
            String compr2 = "QSRG"

            if(compr == fclass_state){


            Intent i = new Intent(OutletsList.this, GdgScoreSheeet.class);
            i.putExtra("outlt", foutname);
            i.putExtra("chnl", fchannel);
            i.putExtra("cls", fclass);
            i.putExtra("clsstate", fclass_state);
            startActivity(i);
            }
            if(compr2 == fclass_state){
            Intent i = new Intent(OutletsList.this, QsrgScoreSheeet.class);
            i.putExtra("outlt", foutname);
            i.putExtra("chnl", fchannel);
            i.putExtra("cls", fclass);
            i.putExtra("clsstate", fclass_state);
            startActivity(i);

            }



        }

    });
}

当我点击它在logcat中显示此错误时，java.lang.ClassCastExeption：java.util.HashMap无法转换为java.lang.String.Ypur非常感谢帮助，甚至替代代码和解决方案。提前谢谢人

Answer 1

问题是你正在将一个HashMap转换为一个字符串，这将给你一个错误ClassCastExeption

<强>问题：

此代码将返回String而不是HashMap

parent.getItemAtPosition(position);

从你的SimpleAdapter开始，你为ListView中的每个项目添加了一个String数组而不是一个HashMap。

 new SimpleAdapter(this, mOutletsList,
                   R.layout.single_outlet, 
                   new String[] { TAG_OUTLET_NAME, TAG_SPARKLING_CHANNEL, TAG_SPARKLING_CLASSIFICATION, TAG_CLASS}, 
                   new int[]{ R.id.outlet_name,     R.id.sparkling_channel, R.id.sparkling_classification, R.id.cls_state});

解决方案1 

除非您为它创建BaseAdapter，否则无法将其强制转换为HashMap，您可以click here学习制作适配器。

解决方案2

其他解决方案是从ListView

获取所有项目数组

        String foutname = parent.getItemAtPosition(0);
        String fchannel = parent.getItemAtPosition(1);
        String fclass = parent.getItemAtPosition(2);
        String fclass_state = parent.getItemAtPosition(3);

Answer 2

可能会有所帮助 -

String classes[]="Start","Send","Tabs","Browser","Flipper","SharedPrefs","InternalData","Sqlite","Checking"};

//从此字符串数组生成列表视图

单击列表项上的

//使用此...请注意try块中的第一行。

String cheese=classes[position];
    try{
        Class cl=Class.forName("com.example.test."+cheese);
        Intent i=new Intent(Menu.this,cl);
        startActivity(i);
    }catch(ClassNotFoundException e){}

使用ListView项目调用android活动单击

2 个答案: