Question

我开展了3项活动。

ElecBillActative
AddBillActivity
活动

我在第二次活动中成功地利用了一名实习生进入了第二次活动,但一旦我在第二次活动中点击了次特顿,我就成为一个例外。

我尝试了许多方法,但我无法理解这一问题。

这是我的标志

E/AndroidRuntime(  506): FATAL EXCEPTION: main
E/AndroidRuntime(  506): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.sai.android.billing/com.sai.android.billing.活动}: java.lang.NullPointerException
E/AndroidRuntime(  506):        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1544)
E/AndroidRuntime(  506):        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1638)
E/AndroidRuntime(  506):        at android.app.ActivityThread.access$1500(ActivityThread.java:117)
E/AndroidRuntime(  506):        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:928)
E/AndroidRuntime(  506):        at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime(  506):        at android.os.Looper.loop(Looper.java:123)
E/AndroidRuntime(  506):        at android.app.ActivityThread.main(ActivityThread.java:3647)
E/AndroidRuntime(  506):        at java.lang.reflect.Method.invokeNative(NativeMethod)
E/AndroidRuntime(  506):        at java.lang.reflect.Method.invoke(Method.java:507)
E/AndroidRuntime(  506):        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
E/AndroidRuntime(  506):        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
E/AndroidRuntime(  506):        at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime(  506): Caused by: java.lang.NullPointerException
E/AndroidRuntime(  506):        at com.sai.android.billing.活动.<init>(活动.java:21)
E/AndroidRuntime(  506):        at java.lang.Class.newInstanceImpl(Native Method)
E/AndroidRuntime(  506):        at java.lang.Class.newInstance(Class.java:1409)
E/AndroidRuntime(  506):        at android.app.Instrumentation.newActivity(Instrumentation.java:1021)
E/AndroidRuntime(  506):        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1536)
E/AndroidRuntime(  506):        ... 11 more
W/ActivityManager(   70):   Force finishing activity com.sai.android.billing/.活动
W/ActivityManager(   70):   Force finishing activity com.sai.android.billing/.AddBillActivity
W/ActivityManager(   70): Activity pause timeout for HistoryRecord{4079d8f8 com.sai.android.billing/.活动}
I/ARMAssembler(   70): generated scanline__00000177:03515104_00001001_00000000 [91 ipp] (114 ins) at [0x445b36e0:0x445b38a8] in 1634844 ns
I/Process (  506): Sending signal. PID: 506 SIG: 9
I/ActivityManager(   70): Process com.sai.android.billing (pid 506) has died.
E/InputDispatcher(   70): channel  4060e840 com.sai.android.billing/com.sai.android.billing.ElecBillingActivity (server)  ~ Consumer closed input channel or an error occurred.  events=0x8
E/InputDispatcher(   70): channel  4060e840 com.sai.android.billing/com.sai.android.billing.ElecBillingActivity (server)  ~ Channel is unrecoverably broken and will be disposed!
I/WindowManager(   70): WIN DEATH: Window{4060e840 com.sai.android.billing/com.sai.android.billing.ElecBillingActivity paused=false}
I/WindowManager(   70): WIN DEATH: Window{406f4868 com.sai.android.billing/com.sai.android.billing.AddBillActivity paused=true}
E/InputDispatcher(   70): Received spurious receive callback for unknown input channel.  fd=151, events=0x8
W/InputManagerService(   70): Got RemoteException sending setActive(false) notification to pid 506 uid 10038

我还为我的。

As my problem seems to big and my class files are too big I provided the download link here.
As I am a new user I am unable to post the screenshots here.

Answer 1

According to the logs you got a NullPointerException in ResultActivity.java on line 21... taking a look into your source code, this is caused by calling getIntent() which is a member function of Activity which can only be called after the Activity is created. Therefore, move your initialization code into the onCreate method.

3. 将贵成员的定义改为:

private TextView resultOk;
int highLimit,lowLimit,highRate,lowRate,defaultRate,amount;
Bundle bundle;
String userName;
String meterNumber;
String prevReading;
String currReading;
int pR;
int cR;
int units;
String u;
String a;

此外,请打电话getIntent (.getExtras(),将其储存在bundle上。但是,由于你从未在<条码>中添加任何内容,<条码>/条码>,<条码>bundle将改为<条码>null,在你尝试<条码>bundle.getString(......)时,它将向另一个<条码>NullPointerException!

作出的第一个改动是提供<代码>android:id属以下表格:xml文档。将其编为<代码>radios,并在<代码>AddBillActective中增加这一行文:

public static RadioGroup radios;

以及<代码>的这个行文方法:

radios = (RadioGroup)findViewById(R.id.radios);

然后修改<代码>addTask

Intent intent1 = new Intent(AddBillActivity.this, ResultActivity.class);
intent1.putExtra("bill_name", billNameEditText.getText().toString());
intent1.putExtra("bill_number", billNumEditText.getText().toString());
intent1.putExtra("bill_previous", billPrevEditText.getText().toString());
intent1.putExtra("bill_current", billCurrEditText.getText().toString());
intent1.putExtra("radio", radios.getCheckedRadioButtonId());
startActivity(intent1);

And now you can get all those extras in your onCreate method in ResultActivity:

bundle = getIntent().getExtras();
userName = bundle.getString("bill_name");
meterNumber = bundle.getString("bill_number");
prevReading = bundle.getString("bill_previous");
currReading = bundle.getString("bill_current");
pR = Integer.parseInt(prevReading);
cR = Integer.parseInt(currReading);
units = pR - cR;
u = bundle.getString(String.valueOf(units));
a = bundle.getString(String.valueOf(units));

(b) 应:

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