为什么即使没有错误我的应用程序也会崩溃（帮助）
Why does my app crash even when there is no error (HELP)
我正在尝试创建一个测验应用程序（尽管我不太擅长使用 android studio）我对代码进行了一些更改并尝试 运行 [=] 上的应用程序25=] 模拟器，我注意到应用程序不断崩溃并拒绝 运行 尽管构建应用程序时没有错误。
可能是什么问题，我怎样才能让应用程序 运行 不崩溃？
这是我从事的第一个项目之一，对 java 和 android 工作室的了解有限。
package com.myafrica.africaquiz;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.RadioButton;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
//Getting the ID of the TextView of the question text
TextView TestQuestionID = (TextView) findViewById(R.id.TestQuestion);
//Getting the ID of the TextView of the question answer
RadioButton AnswerA_ID = (RadioButton) findViewById(R.id.AnswerA);
RadioButton AnswerB_ID = (RadioButton) findViewById(R.id.AnswerB);
RadioButton AnswerC_ID = (RadioButton) findViewById(R.id.AnswerC);
RadioButton AnswerD_ID = (RadioButton) findViewById(R.id.AnswerD);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void GetNextQuestion(View view) {
Question1();
}
/*
This part of the code will contain the answer part of this quiz app.
Each question is a method and that method will be called when the Next
button is clicked in the app.
When the button is clicked the setText() will automatically (re)set the
text in the question layout in the XML
*/
public void Question1() {
TestQuestionID.setText("Which part of Africa can Ghana be located");
AnswerA_ID.setText(" A: West Africa");
AnswerB_ID.setText(" B: East Africa");
AnswerC_ID.setText(" C: Central Africa");
AnswerD_ID.setText(" D: North Africa");
}
}
这是我的 XML 代码
<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/ScrollViewLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<RelativeLayout
android:id="@+id/QuestionViewLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="10dp"
android:text="@string/quiz_progress"
android:textSize="15sp" />
<ProgressBar
style="@style/Widget.AppCompat.ProgressBar.Horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginEnd="10dp"
android:layout_marginTop="12dp" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="40dp"
android:orientation="vertical">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_margin="10dp"
android:text="Question 1 / 50" />
<TextView
android:id="@+id/TestQuestion"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_margin="10dp"
android:text="How old is james Mother?"
android:textSize="20sp" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="125dp"
android:orientation="vertical">
<RadioGroup
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<RadioButton
android:id="@+id/AnswerA"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="10dp"
android:layout_marginTop="10dp"
android:padding="5dp"
android:text=" A: 20" />
<RadioButton
android:id="@+id/AnswerB"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="10dp"
android:layout_marginTop="5dp"
android:padding="5dp"
android:text=" B: 50" />
<RadioButton
android:id="@+id/AnswerC"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="10dp"
android:layout_marginTop="5dp"
android:padding="5dp"
android:text=" B: 100" />
<RadioButton
android:id="@+id/AnswerD"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="10dp"
android:layout_marginTop="5dp"
android:padding="5dp"
android:text=" D: 58" />
</RadioGroup>
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="300dp"
android:gravity="center"
android:orientation="horizontal">
<Button
android:id="@+id/PreviousButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="20dp"
android:padding="10dp"
android:text="@string/Previous"
android:textSize="15sp" />
<Button
android:id="@+id/NextButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="20dp"
android:onClick="GetNextQuestion"
android:padding="10dp"
android:text="@string/Next"
android:textSize="15sp" />
</LinearLayout>
</RelativeLayout>
</ScrollView>
这是来自 Logcat
的详细信息
01-30 14:10:28.606 16454-16454/? I/rica.africaqui: Not late-enabling -
Xcheck:jni (already on)
01-30 14:10:28.648 16454-16454/? W/rica.africaqui: Unexpected CPU variant
for X86 using defaults: x86
01-30 14:10:28.832 16454-16454/com.myafrica.africaquiz I/rica.africaqui:
The ClassLoaderContext is a special shared library.
01-30 14:10:28.992 16454-16454/com.myafrica.africaquiz W/rica.africaqui:
JIT profile information will not be recorded: profile file does not exits.
01-30 14:10:28.995 16454-16454/com.myafrica.africaquiz I/chatty:
uid=10086(com.myafrica.africaquiz) identical 10 lines
01-30 14:10:28.995 16454-16454/com.myafrica.africaquiz W/rica.africaqui:
JIT profile information will not be recorded: profile file does not exits.
01-30 14:10:29.026 16454-16454/com.myafrica.africaquiz I/InstantRun:
starting instant run server: is main process
01-30 14:10:29.252 16454-16454/com.myafrica.africaquiz D/AndroidRuntime:
Shutting down VM
01-30 14:10:29.271 16454-16454/com.myafrica.africaquiz E/AndroidRuntime:
FATAL EXCEPTION: main
Process: com.myafrica.africaquiz, PID: 16454
java.lang.RuntimeException: Unable to instantiate activity
ComponentInfo{com.myafrica.africaquiz/
com.myafrica.africaquiz.MainActivity}:
java.lang.NullPointerException: Attempt to invoke virtual method
'android.view.Window$Callback android.view.Window.getCallback()' on a null
object reference
at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2843)
at
android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
at
android.app.servertransaction.LaunchActivityItem.execute
(LaunchActivityItem.java:78)
at
android.app.servertransaction.TransactionExecutor.executeCallbacks
(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute
(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run
(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual
method 'android.view.Window$Callback android.view.Window.getCallback()'
on a null object reference
at android.support.v7.app.AppCompatDelegateImplBase.<init>
(AppCompatDelegateImplBase.java:117)
at android.support.v7.app.AppCompatDelegateImplV9.<init>
(AppCompatDelegateImplV9.java:149)
at android.support.v7.app.AppCompatDelegateImplV14.<init>
(AppCompatDelegateImplV14.java:56)
at android.support.v7.app.AppCompatDelegateImplV23.<init>
(AppCompatDelegateImplV23.java:31)
at android.support.v7.app.AppCompatDelegateImplN.<init>
(AppCompatDelegateImplN.java:31)
at
android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:198)
at
android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:183)
at
android.support.v7.app.AppCompatActivity.getDelegate
(AppCompatActivity.java:519)
at android.support.v7.app.AppCompatActivity.findViewById
(AppCompatActivity.java:190)
at com.myafrica.africaquiz.MainActivity.<init>(MainActivity.java:13)
at java.lang.Class.newInstance(Native Method)
at
android.app.AppComponentFactory.instantiateActivity
(AppComponentFactory.java:69)
at android.app.Instrumentation.newActivity(Instrumentation.java:1215)
at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2831)
at
android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
at
android.app.servertransaction.LaunchActivityItem.execute
(LaunchActivityItem.java:78)
at android.app.servertransaction.TransactionExecutor.executeCallbacks
(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute
(TransactionExecutor.java:68)
at
android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run
(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
01-30 14:10:29.450 16454-16465/com.myafrica.africaquiz I/rica.africaqui:
Background concurrent copying GC freed 20027(6MB) AllocSpace objects,
0(0B)
LOS
objects, 58% free, 1102KB/2MB, paused 757us total 159.205ms
虽然我还没有完成应用程序的构建，但我想在遇到这个问题之前对其进行测试并查看可能的结果。
您应该在第一步中将 RadioButton 声明为 null :
RadioButton AnswerA_ID = null;
RadioButton AnswerB_ID = null;
RadioButton AnswerC_ID = null;
RadioButton AnswerD_ID = null;
然后在 OnCreate 中你应该做：
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
AnswerA_ID = (RadioButton) findViewById(R.id.AnswerA);
AnswerB_ID = (RadioButton) findViewById(R.id.AnswerB);
AnswerC_ID = (RadioButton) findViewById(R.id.AnswerC);
AnswerD_ID = (RadioButton) findViewById(R.id.AnswerD);
}
我正在尝试创建一个测验应用程序（尽管我不太擅长使用 android studio）我对代码进行了一些更改并尝试 运行 [=] 上的应用程序25=] 模拟器，我注意到应用程序不断崩溃并拒绝 运行 尽管构建应用程序时没有错误。
可能是什么问题，我怎样才能让应用程序 运行 不崩溃？
这是我从事的第一个项目之一，对 java 和 android 工作室的了解有限。
package com.myafrica.africaquiz;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.RadioButton;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
//Getting the ID of the TextView of the question text
TextView TestQuestionID = (TextView) findViewById(R.id.TestQuestion);
//Getting the ID of the TextView of the question answer
RadioButton AnswerA_ID = (RadioButton) findViewById(R.id.AnswerA);
RadioButton AnswerB_ID = (RadioButton) findViewById(R.id.AnswerB);
RadioButton AnswerC_ID = (RadioButton) findViewById(R.id.AnswerC);
RadioButton AnswerD_ID = (RadioButton) findViewById(R.id.AnswerD);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void GetNextQuestion(View view) {
Question1();
}
/*
This part of the code will contain the answer part of this quiz app.
Each question is a method and that method will be called when the Next
button is clicked in the app.
When the button is clicked the setText() will automatically (re)set the
text in the question layout in the XML
*/
public void Question1() {
TestQuestionID.setText("Which part of Africa can Ghana be located");
AnswerA_ID.setText(" A: West Africa");
AnswerB_ID.setText(" B: East Africa");
AnswerC_ID.setText(" C: Central Africa");
AnswerD_ID.setText(" D: North Africa");
}
}
这是我的 XML 代码
<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/ScrollViewLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<RelativeLayout
android:id="@+id/QuestionViewLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="10dp"
android:text="@string/quiz_progress"
android:textSize="15sp" />
<ProgressBar
style="@style/Widget.AppCompat.ProgressBar.Horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginEnd="10dp"
android:layout_marginTop="12dp" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="40dp"
android:orientation="vertical">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_margin="10dp"
android:text="Question 1 / 50" />
<TextView
android:id="@+id/TestQuestion"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_margin="10dp"
android:text="How old is james Mother?"
android:textSize="20sp" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="125dp"
android:orientation="vertical">
<RadioGroup
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<RadioButton
android:id="@+id/AnswerA"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="10dp"
android:layout_marginTop="10dp"
android:padding="5dp"
android:text=" A: 20" />
<RadioButton
android:id="@+id/AnswerB"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="10dp"
android:layout_marginTop="5dp"
android:padding="5dp"
android:text=" B: 50" />
<RadioButton
android:id="@+id/AnswerC"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="10dp"
android:layout_marginTop="5dp"
android:padding="5dp"
android:text=" B: 100" />
<RadioButton
android:id="@+id/AnswerD"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="10dp"
android:layout_marginTop="5dp"
android:padding="5dp"
android:text=" D: 58" />
</RadioGroup>
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="300dp"
android:gravity="center"
android:orientation="horizontal">
<Button
android:id="@+id/PreviousButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="20dp"
android:padding="10dp"
android:text="@string/Previous"
android:textSize="15sp" />
<Button
android:id="@+id/NextButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="20dp"
android:onClick="GetNextQuestion"
android:padding="10dp"
android:text="@string/Next"
android:textSize="15sp" />
</LinearLayout>
</RelativeLayout>
</ScrollView>
这是来自 Logcat
的详细信息01-30 14:10:28.606 16454-16454/? I/rica.africaqui: Not late-enabling -
Xcheck:jni (already on)
01-30 14:10:28.648 16454-16454/? W/rica.africaqui: Unexpected CPU variant
for X86 using defaults: x86
01-30 14:10:28.832 16454-16454/com.myafrica.africaquiz I/rica.africaqui:
The ClassLoaderContext is a special shared library.
01-30 14:10:28.992 16454-16454/com.myafrica.africaquiz W/rica.africaqui:
JIT profile information will not be recorded: profile file does not exits.
01-30 14:10:28.995 16454-16454/com.myafrica.africaquiz I/chatty:
uid=10086(com.myafrica.africaquiz) identical 10 lines
01-30 14:10:28.995 16454-16454/com.myafrica.africaquiz W/rica.africaqui:
JIT profile information will not be recorded: profile file does not exits.
01-30 14:10:29.026 16454-16454/com.myafrica.africaquiz I/InstantRun:
starting instant run server: is main process
01-30 14:10:29.252 16454-16454/com.myafrica.africaquiz D/AndroidRuntime:
Shutting down VM
01-30 14:10:29.271 16454-16454/com.myafrica.africaquiz E/AndroidRuntime:
FATAL EXCEPTION: main
Process: com.myafrica.africaquiz, PID: 16454
java.lang.RuntimeException: Unable to instantiate activity
ComponentInfo{com.myafrica.africaquiz/
com.myafrica.africaquiz.MainActivity}:
java.lang.NullPointerException: Attempt to invoke virtual method
'android.view.Window$Callback android.view.Window.getCallback()' on a null
object reference
at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2843)
at
android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
at
android.app.servertransaction.LaunchActivityItem.execute
(LaunchActivityItem.java:78)
at
android.app.servertransaction.TransactionExecutor.executeCallbacks
(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute
(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run
(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual
method 'android.view.Window$Callback android.view.Window.getCallback()'
on a null object reference
at android.support.v7.app.AppCompatDelegateImplBase.<init>
(AppCompatDelegateImplBase.java:117)
at android.support.v7.app.AppCompatDelegateImplV9.<init>
(AppCompatDelegateImplV9.java:149)
at android.support.v7.app.AppCompatDelegateImplV14.<init>
(AppCompatDelegateImplV14.java:56)
at android.support.v7.app.AppCompatDelegateImplV23.<init>
(AppCompatDelegateImplV23.java:31)
at android.support.v7.app.AppCompatDelegateImplN.<init>
(AppCompatDelegateImplN.java:31)
at
android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:198)
at
android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:183)
at
android.support.v7.app.AppCompatActivity.getDelegate
(AppCompatActivity.java:519)
at android.support.v7.app.AppCompatActivity.findViewById
(AppCompatActivity.java:190)
at com.myafrica.africaquiz.MainActivity.<init>(MainActivity.java:13)
at java.lang.Class.newInstance(Native Method)
at
android.app.AppComponentFactory.instantiateActivity
(AppComponentFactory.java:69)
at android.app.Instrumentation.newActivity(Instrumentation.java:1215)
at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2831)
at
android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
at
android.app.servertransaction.LaunchActivityItem.execute
(LaunchActivityItem.java:78)
at android.app.servertransaction.TransactionExecutor.executeCallbacks
(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute
(TransactionExecutor.java:68)
at
android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run
(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
01-30 14:10:29.450 16454-16465/com.myafrica.africaquiz I/rica.africaqui:
Background concurrent copying GC freed 20027(6MB) AllocSpace objects,
0(0B)
LOS
objects, 58% free, 1102KB/2MB, paused 757us total 159.205ms
虽然我还没有完成应用程序的构建，但我想在遇到这个问题之前对其进行测试并查看可能的结果。
您应该在第一步中将 RadioButton 声明为 null :
RadioButton AnswerA_ID = null;
RadioButton AnswerB_ID = null;
RadioButton AnswerC_ID = null;
RadioButton AnswerD_ID = null;
然后在 OnCreate 中你应该做：
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
AnswerA_ID = (RadioButton) findViewById(R.id.AnswerA);
AnswerB_ID = (RadioButton) findViewById(R.id.AnswerB);
AnswerC_ID = (RadioButton) findViewById(R.id.AnswerC);
AnswerD_ID = (RadioButton) findViewById(R.id.AnswerD);
}