使用复选框空指针异常 [英] Null Pointer Exception using Checkbox
问题描述
我试图通过展示,以显示复选框状态 吐司的,每当用户做点击上的按钮的为我使用AlertDialog我,但得到空指针异常,
完整的logcat:
六月七日至12日:32:44.851:E / AndroidRuntime(783):致命异常:主要
6月7日至12日:32:44.851:E / AndroidRuntime(783):显示java.lang.NullPointerException
6月7日至12日:32:44.851:E / AndroidRuntime(783):在com.example.UploadActivity $ 2.onClick(UploadActivity.java:271)
6月7日至12日:32:44.851:E / AndroidRuntime(783):在android.view.View.performClick(View.java:4204)
6月7日至12日:32:44.851:E / AndroidRuntime(783):在android.view.View $ PerformClick.run(View.java:17355)
6月7日至12日:32:44.851:E / AndroidRuntime(783):在android.os.Handler.handleCallback(Handler.java:725)
6月7日至12日:32:44.851:E / AndroidRuntime(783):在android.os.Handler.dispatchMessage(Handler.java:92)
6月7日至12日:32:44.851:E / AndroidRuntime(783):在android.os.Looper.loop(Looper.java:137)
6月7日至12日:32:44.851:E / AndroidRuntime(783):在android.app.ActivityThread.main(ActivityThread.java:5041)
6月7日至12日:32:44.851:E / AndroidRuntime(783):在java.lang.reflect.Method.invokeNative(本机方法)
6月7日至12日:32:44.851:E / AndroidRuntime(783):在java.lang.reflect.Method.invoke(Method.java:511)
6月7日至12日:32:44.851:E / AndroidRuntime(783):在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run(ZygoteInit.java:793)
6月7日至12日:32:44.851:E / AndroidRuntime(783):在com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
6月7日至12日:32:44.851:E / AndroidRuntime(783):在dalvik.system.NativeStart.main(本机方法)
6月七日至12日:32:50.332:E /跟踪(1213):错误打开跟踪文件:没有这样的文件或目录(2)
loginbutton.setOnClickListener(新View.OnClickListener(){
@覆盖
公共无效的onClick(视图v){
保存数据();
alertDialog.dismiss(); chkSubscribe =(复选框)findViewById(R.id.chkSubscribe);
如果(chkSubscribe.isChecked())
{
Toast.makeText(UploadActivity.this,你已经订阅了时事通讯
Toast.LENGTH_LONG).show();
}
其他{
Toast.makeText(UploadActivity.this,你有未认购通讯,
Toast.LENGTH_LONG).show();
} }
错误行:
com.example.UploadActivity $ 2.onClick(UploadActivity.java:271)
(即):
如果(chkSubscribe.isChecked())
如果你正在膨胀为你的对话框布局
你需要使用对话框对象初始化视图
chkSubscribe =(复选框)dialog.findViewById(R.id.chkSubscribe);
您越来越您还没有初始化NPE堂妹 chkSubscribe
chkSubscribe =(复选框)findViewById(R.id.chkSubscribe)
//初始化失败
您也驳回的对话框在这种情况下
chkSubscribe
将是空的。
请注意:您可以 findViewById
设置为活动当前视图层次
I am trying to show Checkbox Status by showing Toast whenever user do Click on button for that i am using AlertDialog, but getting Null Pointer Exception,
Complete Logcat:
07-12 06:32:44.851: E/AndroidRuntime(783): FATAL EXCEPTION: main
07-12 06:32:44.851: E/AndroidRuntime(783): java.lang.NullPointerException
07-12 06:32:44.851: E/AndroidRuntime(783): at com.example.UploadActivity$2.onClick(UploadActivity.java:271)
07-12 06:32:44.851: E/AndroidRuntime(783): at android.view.View.performClick(View.java:4204)
07-12 06:32:44.851: E/AndroidRuntime(783): at android.view.View$PerformClick.run(View.java:17355)
07-12 06:32:44.851: E/AndroidRuntime(783): at android.os.Handler.handleCallback(Handler.java:725)
07-12 06:32:44.851: E/AndroidRuntime(783): at android.os.Handler.dispatchMessage(Handler.java:92)
07-12 06:32:44.851: E/AndroidRuntime(783): at android.os.Looper.loop(Looper.java:137)
07-12 06:32:44.851: E/AndroidRuntime(783): at android.app.ActivityThread.main(ActivityThread.java:5041)
07-12 06:32:44.851: E/AndroidRuntime(783): at java.lang.reflect.Method.invokeNative(Native Method)
07-12 06:32:44.851: E/AndroidRuntime(783): at java.lang.reflect.Method.invoke(Method.java:511)
07-12 06:32:44.851: E/AndroidRuntime(783): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
07-12 06:32:44.851: E/AndroidRuntime(783): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
07-12 06:32:44.851: E/AndroidRuntime(783): at dalvik.system.NativeStart.main(Native Method)
07-12 06:32:50.332: E/Trace(1213): error opening trace file: No such file or directory (2)
loginbutton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
SaveData();
alertDialog.dismiss();
chkSubscribe = (CheckBox)findViewById(R.id.chkSubscribe);
if (chkSubscribe.isChecked())
{
Toast.makeText(UploadActivity.this,"You have Subscribed for Newsletter",
Toast.LENGTH_LONG).show();
}
else {
Toast.makeText(UploadActivity.this,"You have Un-subscribed for Newsletter",
Toast.LENGTH_LONG).show();
}
}
Error Line:
com.example.UploadActivity$2.onClick(UploadActivity.java:271)
(i.e.):
if (chkSubscribe.isChecked())
If you are inflating a layout for your dialog
you need to use dialog object to initialize view
chkSubscribe = (CheckBox)dialog.findViewById(R.id.chkSubscribe);
You are getting NPE coz you have not initialized chkSubscribe
chkSubscribe = (CheckBox)findViewById(R.id.chkSubscribe)
//Initialization fails
You are also dismissing the dialog
in which case chkSubscribe
will be null.
Note : You can findViewById
of the current view hierarchy set to the activity.
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