更新父片段的DialogFragment引发NullPointerException异常 [英] Updating parent Fragment from DialogFragment raises NullPointerException

问题描述

我挣扎了一会儿点击按钮的正后更新片段从 DialogFragment 。在片段以编程方式添加到活动。当点击一个NullPointerException异常引发的对话框中积极的按钮，因为父片段找不到。
（我不使用 SupportFragments ）

有什么建议？

父活动：

 公共类ResultActivity延伸活动{
    @覆盖
    保护无效的onCreate（捆绑savedInstanceState）{
    super.onCreate（savedInstanceState）;    如果（savedInstanceState == NULL）{
        。getFragmentManager（）调用BeginTransaction（）加（R.id.activity_result，ResultDetailsOneFragment.newInstance（））提交（）。
            }
        }
    }
}
 

的'ResultActivity'的布局：

 ＆LT;？XML版本=1.0编码=UTF-8＆GT？;
＆LT;的FrameLayout的xmlns：机器人=htt​​p://schemas.android.com/apk/res/android
    的xmlns：工具=htt​​p://schemas.android.com/tool​​s
    机器人：ID =@ + ID / activity_result
    工具：上下文=com.myApp.view.ResultActivity
    工具：忽略=MergeRootFrame/＆GT;
 

的'ResultDetailsOneFragment'的布局：

 ＆LT;？XML版本=1.0编码=UTF-8＆GT？;
＆LT;的RelativeLayout的xmlns：机器人=htt​​p://schemas.android.com/apk/res/android
    的xmlns：工具=htt​​p://schemas.android.com/tool​​s
    机器人：ID =@ + ID / fragment_result_details_one
    工具：上下文=$ com.myApp.view.ResultActivity ResultDetailsOneFragment＆GT;
    ＆LT;！ -  ...  - ＆GT;
＆LT; / RelativeLayout的＆GT;
 

回调接口：

 公共接口EditResultDialogListener {
    无效onDialogFinish（）;
}
 

的 DialogFragment ：

 公共类EditDescriptionDialog扩展DialogFragment {
    @覆盖
    保护无效onDialogPositiveButtonClick（DialogInterface对话，诠释它）{
        EditResultDialogListener resultDetailsOneFragment
            =（EditResultDialogListener）getFragmentManager（）findFragmentById（R.id.fragment_result_details_one）。        / *这里的NullPointerException异常* /
        resultDetailsOneFragment.onDialogFinish（）;
    }
}
 

解决方案

您也越来越空指针异常，因为你正在努力寻找对话片段内的片段。

您需要做的是什么 - >

显示对话框时，设置的目的片段...

  dialogFragment.setTargetFragment（ResultDetailsOneFragment.this，MY_REQUEST_ code）;
dialogFragment.show（getFragmentManager（），标签）;
 

然后在你的onDialogPositiveClick，

  @覆盖
保护无效onDialogPositiveButtonClick（DialogInterface对话，诠释它）{
    //发送事件回父片段
    getTargetFragment（）的onActivityResult（MY_REQUEST_ code，Activity.RESULT_OK，NULL）;
}
 

所以在对话框正按一下按钮，您的片段的onActivityResult会被调用。
确保你覆盖的onActivityResult在你的片段类。

I've struggled a while to update a Fragment from a DialogFragment after clicking the positive button. The Fragment is added programmatically to an Activity. When clicking the positive button in the dialog a NullPointerException raises, because the parent Fragment could not be found. (I don't use SupportFragments.)

Any suggestions?

The parent Activity:

public class ResultActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    if (savedInstanceState == null) {
        getFragmentManager().beginTransaction().add(R.id.activity_result, ResultDetailsOneFragment.newInstance()).commit();
            }
        }
    }
}

The layout of 'ResultActivity':

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_result"
    tools:context="com.myApp.view.ResultActivity"
    tools:ignore="MergeRootFrame" />

The layout of 'ResultDetailsOneFragment':

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/fragment_result_details_one"
    tools:context="com.myApp.view.ResultActivity$ResultDetailsOneFragment" >
    <!-- ... -->
</RelativeLayout>

The interface for the callback:

public interface EditResultDialogListener {
    void onDialogFinish();
}

The DialogFragment:

public class EditDescriptionDialog extends DialogFragment {
    @Override
    protected void onDialogPositiveButtonClick(DialogInterface dialog, int which) {
        EditResultDialogListener resultDetailsOneFragment 
            = (EditResultDialogListener) getFragmentManager().findFragmentById(R.id.fragment_result_details_one);

        /* here's the NullPointerException */
        resultDetailsOneFragment.onDialogFinish();
    }
}

解决方案

You are getting nullpointer exception because you are trying to find the fragment inside the dialog fragment.

What you need to do is ->

Set the target fragment when showing the dialog ...

dialogFragment.setTargetFragment(ResultDetailsOneFragment.this, MY_REQUEST_CODE);
dialogFragment.show(getFragmentManager(), "tag");

Then in your onDialogPositiveClick,

@Override
protected void onDialogPositiveButtonClick(DialogInterface dialog, int which) {
    // Send event back to parent fragment
    getTargetFragment().onActivityResult(MY_REQUEST_CODE, Activity.RESULT_OK, null);
}

So on dialog positive button click, the onActivityResult of your Fragment will be called. Make sure you override the onActivityResult in your fragment class.

这篇关于更新父片段的DialogFragment引发NullPointerException异常的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！