复选框堪称Android系统时器isChecked（），它给空指针异常 [英] when isChecked() of checkbox called in android, it gives null pointer exception

问题描述

我在Android的新的。我试图执行以下code，但应用程序崩溃，
在以下code，如果条件导致的NullPointerException这是粗体文字
请检查以下code ......
我分享我的code。感谢.....

 私人无效showGroupChatDialog（）
    {
        ContentResolver的CR = getContentResolver（）;        Imps.ProviderSettings.QueryMap设置=新Imps.ProviderSettings.QueryMap（
                CR，mLastProviderId，假/ *不保持更新* /空/ *无程序* /）;        字符串chatDomain =发布会。 + settings.getDomain（）;        settings.close（）;
     //这个例子说明了如何自定义布局添加到AlertDialog
        LayoutInflater厂= LayoutInflater.from（本）;
        最后查看textEntryView = factory.inflate（R.layout.alert_dialog_group_chat，NULL）;
        最终的TextView tvServer =（TextView中）textEntryView.findViewById（R.id.chat_server）;        tvServer.setText（chatDomain）;        新AlertDialog.Builder（本）
            .setTitle（R.string.create_or_join_group_chat）
            .setView（textEntryView）
            .setPositiveButton（R.string.connect，新DialogInterface.OnClickListener（）{
                公共无效的onClick（DialogInterface对话，诠释whichButton）{                    / *用户点击OK等做一些东西* /                    字符串聊天室= NULL;
                    字符串的ChatServer = NULL;
                    INT enablegrouphistory;
                    // INT opentoall;                    TextView的电视=（TextView中）textEntryView.findViewById（R.id.chat_room）;                    聊天室= tv.getText（）的toString（）。                    电视=（TextView中）textEntryView.findViewById（R.id.chat_server）;                    。的ChatServer = tv.getText（）的toString（）;                    **复选框enablehistory =（复选框）findViewById（R.id.enable_group_history）;
                    如果（enablehistory.isChecked（））{
                        enablegrouphistory = 1;
                    }
                    复选框openall =（复选框）findViewById（R.id.open_to_all）;
                    如果（openall.isChecked（））{
                        opentoall = 1;
                    } **                    startGroupChat（聊天室，的ChatServer，（（IMAPP）getApplication（））的getConnection（mLastProviderId））;                }
            }）
            .setNegativeButton（R.string.cancel，新DialogInterface.OnClickListener（）{
                公共无效的onClick（DialogInterface对话，诠释whichButton）{                    / *用户点击取消，以便做一些东西* /
                }
            }）
            .create（）显示（）。    }
 

解决方案

我猜的意见属于 alert_dialog_group_chat.xml 。

所以更改

 复选框enablehistory =（复选框）findViewById（R.id.enable_group_history）;
 

到

 复选框enablehistory =（复选框）textEntryView.findViewById（R.id.enable_group_history）;
 

同样

 复选框openall =（复选框）textEntryView.findViewById（R.id.open_to_all）;
 

您也越来越 NullPointerException异常为 findViewById 查找在当前膨胀布局的视图。

I am new in android. i am trying to execute following code but the application crashes, In following code, if condition causes the nullpointerexception which is in bold text please check the following code...... I am sharing my code. thanks.....

private void showGroupChatDialog ()
    {
        ContentResolver cr = getContentResolver();

        Imps.ProviderSettings.QueryMap settings = new Imps.ProviderSettings.QueryMap(
                cr, mLastProviderId, false /* don't keep updated */, null /* no handler */);

        String chatDomain = "conference." + settings.getDomain();

        settings.close();


     // This example shows how to add a custom layout to an AlertDialog
        LayoutInflater factory = LayoutInflater.from(this);
        final View textEntryView = factory.inflate(R.layout.alert_dialog_group_chat, null);
        final TextView tvServer = (TextView) textEntryView.findViewById(R.id.chat_server);

        tvServer.setText(chatDomain);

        new AlertDialog.Builder(this)
            .setTitle(R.string.create_or_join_group_chat)
            .setView(textEntryView)
            .setPositiveButton(R.string.connect, new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int whichButton) {

                    /* User clicked OK so do some stuff */

                    String chatRoom = null;
                    String chatServer = null;
                    int enablegrouphistory;
                    //int opentoall;

                    TextView tv = (TextView)textEntryView.findViewById(R.id.chat_room);

                    chatRoom = tv.getText().toString();

                    tv = (TextView) textEntryView.findViewById(R.id.chat_server);

                    chatServer = tv.getText().toString();

                    **CheckBox enablehistory = (CheckBox) findViewById(R.id.enable_group_history);
                    if (enablehistory.isChecked()) {
                        enablegrouphistory = 1;
                    }
                    CheckBox openall = (CheckBox) findViewById(R.id.open_to_all);
                    if(openall.isChecked()){
                        opentoall = 1;
                    }**

                    startGroupChat (chatRoom, chatServer, ((ImApp)getApplication()).getConnection(mLastProviderId));

                }
            })
            .setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int whichButton) {

                    /* User clicked cancel so do some stuff */
                }
            })
            .create().show();

    }

解决方案

I guess the views belongs to alert_dialog_group_chat.xml.

So change

CheckBox enablehistory = (CheckBox) findViewById(R.id.enable_group_history);

to

CheckBox enablehistory = (CheckBox) textEntryView.findViewById(R.id.enable_group_history);

Similarly

CheckBox openall = (CheckBox) textEntryView.findViewById(R.id.open_to_all);

You are getting NUllPointerException as findViewById looks for a view in the current inflated layout.

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