我正在尝试使用其他应用中收到的文字填充EditText Fragment中的NullPointerException。
EditText包含一个值，但我不确定为什么我会得到public class AddTab extends Fragment implements View.OnClickListener {
View view;
Button mButton;
EditText textBox;
String url;
private OnFragmentInteractionListener mListener;
public AddTab() {
// Required empty public constructor
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
// Inflate the layout for this fragment
view = inflater.inflate(R.layout.fragment_add, container, false);
mButton = (Button)view.findViewById(R.id.button);
textBox = (EditText) view.findViewById(R.id.editText);
mButton.setOnClickListener(
new View.OnClickListener() {
public void onClick(View view) {
//some code
}
});
return view;
}
...
// some other methods
public void receiveURL(String url) {
textBox.setText(url);
//this is where I'm getting the exception. Does EditText hold the value it has got in onCreateView()??
}
}
。
这是我的片段类：
03-24 13:30:56.986 7424-7424/? E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.nikhil.amazon1, PID: 7424
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.nikhil.amazon1/com.example.nikhil.amazon1.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.EditText.setText(java.lang.CharSequence)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.EditText.setText(java.lang.CharSequence)' on a null object reference
at com.example.nikhil.amazon1.AddTab.receiveURL(AddTab.java:122)
at com.example.nikhil.amazon1.MainActivity.handleSendText(MainActivity.java:102)
at com.example.nikhil.amazon1.MainActivity.onCreate(MainActivity.java:82)
at android.app.Activity.performCreate(Activity.java:5933)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
如何在此处正确更新片段的UI。 iepopulate我的EditText与传递给receiveURL方法的值？
请帮忙吗？
谢谢！
编辑：
StackTrace：
public class MainActivity extends FragmentActivity implements ListTab.OnFragmentInteractionListener, AddTab.OnFragmentInteractionListener{
PendingIntent pendingIntent;
MyPagerAdapter objAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ViewPager pager = (ViewPager) findViewById(R.id.pager);
objAdapter = new MyPagerAdapter(getSupportFragmentManager());
pager.setAdapter(objAdapter);
// Bind the tabs to the ViewPager
PagerSlidingTabStrip tabs = (PagerSlidingTabStrip) findViewById(R.id.tabs);
pager.setCurrentItem(1);
tabs.setShouldExpand(true);
tabs.setViewPager(pager);
//code for listening to intent from browser or other apps
// Get intent, action and MIME type
Intent intent = getIntent();
String action = intent.getAction();
String type = intent.getType();
if (Intent.ACTION_SEND.equals(action) && type != null) {
if ("text/plain".equals(type)) {
handleSendText(intent); // Handle text being sent
}
}
}
void handleSendText(Intent intent) {
String sharedText = intent.getStringExtra(Intent.EXTRA_TEXT);
if (sharedText != null) {
Fragment f = objAdapter.getItem(1);
AddTab t = (AddTab) f;
t.receiveURL(sharedText);
//from here I'm calling
}
}
}
MainActivity类：从这个类我正在调用receiveURL（）方法。
pagerslidingtabstrip我正在使用AddTab来创建标签页。我获得了适配器的引用并得到了我的片段receiveURL().的实例。然后调用我的方法{{1}}
只有当用户从其他应用程序共享URL（文本）时，才会发生这一切。
答案 0 :(得分：0)
在片段中创建一个全局变量，如
String receivedUrl;
进行如下更改：
public void receiveURL(String url)
{
receivedUrl = url;
}
在onCreateView中进行以下更改
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
view = inflater.inflate(R.layout.fragment_add, container, false);
mButton = (Button)view.findViewById(R.id.button);
textBox = (EditText) view.findViewById(R.id.editText);
textBox.setText(receivedUrl);
mButton.setOnClickListener(
new View.OnClickListener()
{
public void onClick(View view)
{
//some code
}
});
return view;
}
希望这有效。
编辑：
进行以下更改。在你的onCreate for MainActivity中。
String url;
Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Intent intent = getIntent();
String action = intent.getAction();
String type = intent.getType();
if (Intent.ACTION_SEND.equals(action) && type != null) {
if ("text/plain".equals(type)) {
url = handleSendText(intent); // Handle text being sent
}
}
ViewPager pager = (ViewPager) findViewById(R.id.pager);
objAdapter = new MyPagerAdapter(getSupportFragmentManager());
pager.setAdapter(objAdapter);
// Bind the tabs to the ViewPager
PagerSlidingTabStrip tabs = (PagerSlidingTabStrip) findViewById(R.id.tabs);
pager.setCurrentItem(1);
tabs.setShouldExpand(true);
tabs.setViewPager(pager);
//code for listening to intent from browser or other apps
// Get intent, action and MIME type
}
String handleSendText(Intent intent) {
String sharedText = intent.getStringExtra(Intent.EXTRA_TEXT);
if (sharedText != null) {
return sharedText;
}
return null;
}
在MyPagerAdapter中
getItem(int arg0) {
Fragment f = null;
AddTab tab = new AddTab();
tab.requireUrl(url);
f = tab;
return f;
}
答案 1 :(得分：0)
在设置文字之前，请尝试使用以下代码重新初始化您的编辑文字：
textBox = (EditText) getView().findViewById(R.id.editText);
另外请分享一下，如果它没有用，你如何调用receiveURL方法。
答案 2 :(得分：0)
尝试使用本地广播
BroadcastReceiver receiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
String g=i.getStringExtra("key")
textBox.setText(g);
}
};
在AddTab的onCreateView中注册接收器..
getActivity().registerReceiver(receiver, new IntentFilter("refresh"));
从您需要更新textview的地方调用广播
Intent refreshIntent = new Intent("refresh");
refreshIntent.putExtra("key", "valueto be passed");
getActivity().sendBroadcast(refreshIntent);
不要忘记取消注册onDestroyView
中的广播@Override
public void onDestroyView() {
// TODO Auto-generated method stub
super.onDestroyView();
getActivity().unregisterReceiver(receiver);
ButterKnife.reset(this);
}