当我启动其他 Activity 而不是主 Activity 时，应用程序崩溃。
我已尝试删除 Activity “问题”中的部分代码，以查明是哪部分代码导致了此问题。
我完全不熟悉 stackoverflow、android studio 和 javascript 编码。我正在尝试制作此应用程序，并在问题 Activity 中找到了所有代码。我不会自己编码，但我正在尝试通过谷歌搜索来学习它。
该应用程序有一个可点击的 TextView ，可以正常工作。但是，当我添加从此处获取的代码时它不起作用:Display multiple choice questions in a random order
这是崩溃的 Activity 代码:
package com.example.myapplicationjava;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;
public class questions extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_questions);
Scanner input = new Scanner(System.in);
class Question {
/*Read about private access specifier and getter/setter methods*/
private String question;
private String correctOption;
private Question(String question, String correctOption) {
this.question = question;
this.correctOption = correctOption;
}
}
List<Question> allQuestions = new ArrayList<>();
allQuestions.add(new Question("YOUR_QUESTION", "CORRECT_OPTION"));
/*Example:*/
allQuestions.add(new Question("question \n A. answer1 \n B. answer2 \n C. answer3", "B"));
/* TODO do this for all the 15 questions*/
Collections.shuffle(allQuestions);
//TODO prepare allQuestions as explained above
int correct = 0;
for (int i = 0; i < allQuestions.size(); i++) {
Question curQuest = allQuestions.get(i);
System.out.println(curQuest.question);
String ans = input.next();
if(ans.equalsIgnoreCase(curQuest.correctOption)) {
System.out.println("Correct");
correct++;
} else {
System.out.println("incorrect");
}
}
System.out.println("You got "+ correct++ +"/15 good or bad job i guess");
}
}
当这部分代码没有注释时，启动此 Activity 会使应用程序崩溃:
//TODO prepare allQuestions as explained above
int correct = 0;
for (int i = 0; i < allQuestions.size(); i++) {
Question curQuest = allQuestions.get(i);
System.out.println(curQuest.question);
String ans = input.next();
if(ans.equalsIgnoreCase(curQuest.correctOption)) {
System.out.println("Correct");
correct++;
} else {
System.out.println("incorrect");
}
}
System.out.println("You got "+ correct++ +"/15 good or bad job i guess");
我希望应用程序写入终端选项卡？，但它是空的。我还希望该应用程序不会崩溃。另一篇关于应用程序崩溃的帖子要求提供 logcat 日志。在这里:
2019-06-21 17:04:51.426 1634-1645/? I/ActivityManager: START u0 {cmp=com.example.myapplicationjava/.questions} from uid 10080 on display 0
--------- beginning of main
2019-06-21 17:04:51.435 1390-1412/? W/audio_hw_generic: Not supplying enough data to HAL, expected position 7105255 , only wrote 7104960
2019-06-21 17:04:51.469 13313-13313/com.example.myapplicationjava I/System.out: YOUR_QUESTION
2019-06-21 17:04:51.470 13313-13313/com.example.myapplicationjava D/AndroidRuntime: Shutting down VM
--------- beginning of crash
2019-06-21 17:04:51.470 13313-13313/com.example.myapplicationjava E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.myapplicationjava, PID: 13313
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.myapplicationjava/com.example.myapplicationjava.questions}: java.util.NoSuchElementException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
Caused by: java.util.NoSuchElementException
at java.util.Scanner.throwFor(Scanner.java:874)
at java.util.Scanner.next(Scanner.java:1388)
at com.example.myapplicationjava.questions.onCreate(questions.java:47)
at android.app.Activity.performCreate(Activity.java:6662)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
2019-06-21 17:04:51.483 1634-1988/? W/ActivityManager: Force finishing activity com.example.myapplicationjava/.questions
2019-06-21 17:04:51.528 1634-1988/? W/ActivityManager: Force finishing activity com.example.myapplicationjava/.MainActivity
2019-06-21 17:04:51.613 1634-8411/? I/OpenGLRenderer: Initialized EGL, version 1.4
2019-06-21 17:04:51.613 1634-8411/? D/OpenGLRenderer: Swap behavior 1
2019-06-21 17:04:51.614 1634-8411/? W/OpenGLRenderer: Failed to choose config with EGL_SWAP_BEHAVIOR_PRESERVED, retrying without...
2019-06-21 17:04:51.614 1634-8411/? D/OpenGLRenderer: Swap behavior 0
2019-06-21 17:04:51.621 1634-8411/? D/EGL_emulation: eglCreateContext: 0xa00d92c0: maj 2 min 0 rcv 2
2019-06-21 17:04:51.637 1634-8411/? D/EGL_emulation: eglMakeCurrent: 0xa00d92c0: ver 2 0 (tinfo 0x889fe540)
2019-06-21 17:04:51.645 1634-8411/? D/EGL_emulation: eglMakeCurrent: 0xa00d92c0: ver 2 0 (tinfo 0x889fe540)
2019-06-21 17:04:52.029 1634-1647/? W/ActivityManager: Activity pause timeout for ActivityRecord{7589e89 u0 com.example.myapplicationjava/.questions t37 f}
2019-06-21 17:04:52.180 2115-2267/? D/EGL_emulation: eglMakeCurrent: 0xa2b85300: ver 2 0 (tinfo 0xa2b83640)
2019-06-21 17:04:52.693 2115-2267/? W/OpenGLRenderer: Incorrectly called buildLayer on View: ShortcutAndWidgetContainer, destroying layer...
2019-06-21 17:04:54.662 1390-1413/? W/audio_hw_generic: Not supplying enough data to HAL, expected position 7412695 , only wrote 7259760
2019-06-21 17:05:02.632 1634-1647/? W/ActivityManager: Activity destroy timeout for ActivityRecord{7589e89 u0 com.example.myapplicationjava/.questions t37 f}
2019-06-21 17:05:02.633 1634-1647/? W/ActivityManager: Activity destroy timeout for ActivityRecord{62c23a u0 com.example.myapplicationjava/.MainActivity t37 f}
2019-06-21 17:05:02.633 1634-1647/? I/WindowManager: Destroying surface Surface(name=com.example.myapplicationjava/com.example.myapplicationjava.MainActivity) called by com.android.server.wm.WindowStateAnimator.destroySurface:2016 com.android.server.wm.WindowStateAnimator.destroySurfaceLocked:882 com.android.server.wm.WindowState.removeLocked:1456 com.android.server.wm.WindowManagerService.removeWindowInnerLocked:2484 com.android.server.wm.WindowManagerService.removeWindowLocked:2442 com.android.server.wm.WindowManagerService.removeWindowLocked:2311 com.android.server.wm.AppWindowToken.removeAllWindows:530 com.android.server.wm.AppWindowToken.removeAppFromTaskLocked:326
编辑:当检查 input.next 是否为 null 时应用仍然崩溃:
//TODO prepare allQuestions as explained above
int correct = 0;
for (int i = 0; i < allQuestions.size(); i++) {
Question curQuest = allQuestions.get(i);
System.out.println(curQuest.question);
String ans = input.next();
if(ans != null && ans.equalsIgnoreCase(curQuest.correctOption)) {
System.out.println("Correct");
correct++;
} else {
System.out.println("incorrect");
}
}
System.out.println("You got "+ correct++ +"/15 good or bad job i guess");
有时选择 YOUR_QUESTION 示例问题时会显示旧日志。当从洗牌中选择另一个问题时，这是日志:
2019-06-21 18:03:00.435 15047-15047/? I/art: Not late-enabling -Xcheck:jni (already on)
2019-06-21 18:03:00.435 15047-15047/? W/art: Unexpected CPU variant for X86 using defaults: x86
2019-06-21 18:03:00.669 15047-15047/com.example.myapplicationjava W/System: ClassLoader referenced unknown path: /data/app/com.example.myapplicationjava-1/lib/x86
2019-06-21 18:03:00.679 15047-15047/com.example.myapplicationjava I/InstantRun: starting instant run server: is main process
2019-06-21 18:03:00.767 15047-15047/com.example.myapplicationjava W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter androidx.vectordrawable.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
2019-06-21 18:03:00.816 15047-15047/com.example.myapplicationjava I/art: Rejecting re-init on previously-failed class java.lang.Class<androidx.core.view.ViewCompat$OnUnhandledKeyEventListenerWrapper>: java.lang.NoClassDefFoundError: Failed resolution of: Landroid/view/View$OnUnhandledKeyEventListener;
2019-06-21 18:03:00.816 15047-15047/com.example.myapplicationjava I/art: at void androidx.core.view.ViewCompat.setBackground(android.view.View, android.graphics.drawable.Drawable) (ViewCompat.java:2341)
2019-06-21 18:03:00.816 15047-15047/com.example.myapplicationjava I/art: at void androidx.appcompat.widget.ActionBarContainer.<init>(android.content.Context, android.util.AttributeSet) (ActionBarContainer.java:62)
2019-06-21 18:03:00.816 15047-15047/com.example.myapplicationjava I/art: at java.lang.Object java.lang.reflect.Constructor.newInstance0!(java.lang.Object[]) (Constructor.java:-2)
2019-06-21 18:03:00.816 15047-15047/com.example.myapplicationjava I/art: at java.lang.Object java.lang.reflect.Constructor.newInstance(java.lang.Object[]) (Constructor.java:430)
2019-06-21 18:03:00.816 15047-15047/com.example.myapplicationjava I/art: at android.view.View android.view.LayoutInflater.createView(java.lang.String, java.lang.String, android.util.AttributeSet) (LayoutInflater.java:645)
2019-06-21 18:03:00.816 15047-15047/com.example.myapplicationjava I/art: at android.view.View android.view.LayoutInflater.createViewFromTag(android.view.View, java.lang.String, android.content.Context, android.util.AttributeSet, boolean) (LayoutInflater.java:787)
2019-06-21 18:03:00.816 15047-15047/com.example.myapplicationjava I/art: at android.view.View android.view.LayoutInflater.createViewFromTag(android.view.View, java.lang.String, android.content.Context, android.util.AttributeSet) (LayoutInflater.java:727)
2019-06-21 18:03:00.816 15047-15047/com.example.myapplicationjava I/art: at void android.view.LayoutInflater.rInflate(org.xmlpull.v1.XmlPullParser, android.view.View, android.content.Context, android.util.AttributeSet, boolean) (LayoutInflater.java:858)
2019-06-21 18:03:00.816 15047-15047/com.example.myapplicationjava I/art: at void android.view.LayoutInflater.rInflateChildren(org.xmlpull.v1.XmlPullParser, android.view.View, android.util.AttributeSet, boolean) (LayoutInflater.java:821)
2019-06-21 18:03:00.816 15047-15047/com.example.myapplicationjava I/art: at android.view.View android.view.LayoutInflater.inflate(org.xmlpull.v1.XmlPullParser, android.view.ViewGroup, boolean) (LayoutInflater.java:518)
2019-06-21 18:03:00.816 15047-15047/com.example.myapplicationjava I/art: at android.view.View android.view.LayoutInflater.inflate(int, android.view.ViewGroup, boolean) (LayoutInflater.java:426)
2019-06-21 18:03:00.816 15047-15047/com.example.myapplicationjava I/art: at android.view.View android.view.LayoutInflater.inflate(int, android.view.ViewGroup) (LayoutInflater.java:377)
2019-06-21 18:03:00.816 15047-15047/com.example.myapplicationjava I/art: at android.view.ViewGroup androidx.appcompat.app.AppCompatDelegateImpl.createSubDecor() (AppCompatDelegateImpl.java:607)
2019-06-21 18:03:00.816 15047-15047/com.example.myapplicationjava I/art: at void androidx.appcompat.app.AppCompatDelegateImpl.ensureSubDecor() (AppCompatDelegateImpl.java:518)
2019-06-21 18:03:00.816 15047-15047/com.example.myapplicationjava I/art: at void androidx.appcompat.app.AppCompatDelegateImpl.setContentView(int) (AppCompatDelegateImpl.java:466)
2019-06-21 18:03:00.816 15047-15047/com.example.myapplicationjava I/art: at void androidx.appcompat.app.AppCompatActivity.setContentView(int) (AppCompatActivity.java:140)
2019-06-21 18:03:00.816 15047-15047/com.example.myapplicationjava I/art: at void com.example.myapplicationjava.MainActivity.onCreate(android.os.Bundle) (MainActivity.java:16)
2019-06-21 18:03:00.816 15047-15047/com.example.myapplicationjava I/art: at void android.app.Activity.performCreate(android.os.Bundle) (Activity.java:6662)
2019-06-21 18:03:00.816 15047-15047/com.example.myapplicationjava I/art: at void android.app.Instrumentation.callActivityOnCreate(android.app.Activity, android.os.Bundle) (Instrumentation.java:1118)
2019-06-21 18:03:00.816 15047-15047/com.example.myapplicationjava I/art: at android.app.Activity android.app.ActivityThread.performLaunchActivity(android.app.ActivityThread$ActivityClientRecord, android.content.Intent) (ActivityThread.java:2599)
2019-06-21 18:03:00.816 15047-15047/com.example.myapplicationjava I/art: at void android.app.ActivityThread.handleLaunchActivity(android.app.ActivityThread$ActivityClientRecord, android.content.Intent, java.lang.String) (ActivityThread.java:2707)
2019-06-21 18:03:00.816 15047-15047/com.example.myapplicationjava I/art: at void android.app.ActivityThread.-wrap12(android.app.ActivityThread, android.app.ActivityThread$ActivityClientRecord, android.content.Intent, java.lang.String) (ActivityThread.java:-1)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at void android.app.ActivityThread$H.handleMessage(android.os.Message) (ActivityThread.java:1460)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at void android.os.Handler.dispatchMessage(android.os.Message) (Handler.java:102)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at void android.os.Looper.loop() (Looper.java:154)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at void android.app.ActivityThread.main(java.lang.String[]) (ActivityThread.java:6077)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at java.lang.Object java.lang.reflect.Method.invoke!(java.lang.Object, java.lang.Object[]) (Method.java:-2)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at void com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run() (ZygoteInit.java:866)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at void com.android.internal.os.ZygoteInit.main(java.lang.String[]) (ZygoteInit.java:756)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: Caused by: java.lang.ClassNotFoundException: Didn't find class "android.view.View$OnUnhandledKeyEventListener" on path: DexPathList[[zip file "/data/app/com.example.myapplicationjava-1/base.apk", zip file "/data/app/com.example.myapplicationjava-1/split_lib_dependencies_apk.apk", zip file "/data/app/com.example.myapplicationjava-1/split_lib_slice_0_apk.apk", zip file "/data/app/com.example.myapplicationjava-1/split_lib_slice_1_apk.apk", zip file "/data/app/com.example.myapplicationjava-1/split_lib_slice_2_apk.apk", zip file "/data/app/com.example.myapplicationjava-1/split_lib_slice_3_apk.apk", zip file "/data/app/com.example.myapplicationjava-1/split_lib_slice_4_apk.apk", zip file "/data/app/com.example.myapplicationjava-1/split_lib_slice_5_apk.apk", zip file "/data/app/com.example.myapplicationjava-1/split_lib_slice_6_apk.apk", zip file "/data/app/com.example.myapplicationjava-1/split_lib_slice_7_apk.apk", zip file "/data/app/com.example.myapplicationjava-1/split_lib_slice_8_apk.apk", zip file "/data/app/co
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at java.lang.Class dalvik.system.BaseDexClassLoader.findClass(java.lang.String) (BaseDexClassLoader.java:56)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at java.lang.Class java.lang.ClassLoader.loadClass(java.lang.String, boolean) (ClassLoader.java:380)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at java.lang.Class java.lang.ClassLoader.loadClass(java.lang.String) (ClassLoader.java:312)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at void androidx.core.view.ViewCompat.setBackground(android.view.View, android.graphics.drawable.Drawable) (ViewCompat.java:2341)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at void androidx.appcompat.widget.ActionBarContainer.<init>(android.content.Context, android.util.AttributeSet) (ActionBarContainer.java:62)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at java.lang.Object java.lang.reflect.Constructor.newInstance0!(java.lang.Object[]) (Constructor.java:-2)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at java.lang.Object java.lang.reflect.Constructor.newInstance(java.lang.Object[]) (Constructor.java:430)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at android.view.View android.view.LayoutInflater.createView(java.lang.String, java.lang.String, android.util.AttributeSet) (LayoutInflater.java:645)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at android.view.View android.view.LayoutInflater.createViewFromTag(android.view.View, java.lang.String, android.content.Context, android.util.AttributeSet, boolean) (LayoutInflater.java:787)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at android.view.View android.view.LayoutInflater.createViewFromTag(android.view.View, java.lang.String, android.content.Context, android.util.AttributeSet) (LayoutInflater.java:727)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at void android.view.LayoutInflater.rInflate(org.xmlpull.v1.XmlPullParser, android.view.View, android.content.Context, android.util.AttributeSet, boolean) (LayoutInflater.java:858)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at void android.view.LayoutInflater.rInflateChildren(org.xmlpull.v1.XmlPullParser, android.view.View, android.util.AttributeSet, boolean) (LayoutInflater.java:821)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at android.view.View android.view.LayoutInflater.inflate(org.xmlpull.v1.XmlPullParser, android.view.ViewGroup, boolean) (LayoutInflater.java:518)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at android.view.View android.view.LayoutInflater.inflate(int, android.view.ViewGroup, boolean) (LayoutInflater.java:426)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at android.view.View android.view.LayoutInflater.inflate(int, android.view.ViewGroup) (LayoutInflater.java:377)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at android.view.ViewGroup androidx.appcompat.app.AppCompatDelegateImpl.createSubDecor() (AppCompatDelegateImpl.java:607)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at void androidx.appcompat.app.AppCompatDelegateImpl.ensureSubDecor() (AppCompatDelegateImpl.java:518)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at void androidx.appcompat.app.AppCompatDelegateImpl.setContentView(int) (AppCompatDelegateImpl.java:466)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at void androidx.appcompat.app.AppCompatActivity.setContentView(int) (AppCompatActivity.java:140)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at void com.example.myapplicationjava.MainActivity.onCreate(android.os.Bundle) (MainActivity.java:16)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at void android.app.Activity.performCreate(android.os.Bundle) (Activity.java:6662)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at void android.app.Instrumentation.callActivityOnCreate(android.app.Activity, android.os.Bundle) (Instrumentation.java:1118)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at android.app.Activity android.app.ActivityThread.performLaunchActivity(android.app.ActivityThread$ActivityClientRecord, android.content.Intent) (ActivityThread.java:2599)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at void android.app.ActivityThread.handleLaunchActivity(android.app.ActivityThread$ActivityClientRecord, android.content.Intent, java.lang.String) (ActivityThread.java:2707)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at void android.app.ActivityThread.-wrap12(android.app.ActivityThread, android.app.ActivityThread$ActivityClientRecord, android.content.Intent, java.lang.String) (ActivityThread.java:-1)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at void android.app.ActivityThread$H.handleMessage(android.os.Message) (ActivityThread.java:1460)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at void android.os.Handler.dispatchMessage(android.os.Message) (Handler.java:102)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at void android.os.Looper.loop() (Looper.java:154)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at void android.app.ActivityThread.main(java.lang.String[]) (ActivityThread.java:6077)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at java.lang.Object java.lang.reflect.Method.invoke!(java.lang.Object, java.lang.Object[]) (Method.java:-2)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at void com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run() (ZygoteInit.java:866)
2019-06-21 18:03:00.817 15047-15047/com.example.myapplicationjava I/art: at void com.android.internal.os.ZygoteInit.main(java.lang.String[]) (ZygoteInit.java:756)
2019-06-21 18:03:01.235 15047-15064/com.example.myapplicationjava I/OpenGLRenderer: Initialized EGL, version 1.4
2019-06-21 18:03:01.235 15047-15064/com.example.myapplicationjava D/OpenGLRenderer: Swap behavior 1
2019-06-21 18:03:01.235 15047-15064/com.example.myapplicationjava W/OpenGLRenderer: Failed to choose config with EGL_SWAP_BEHAVIOR_PRESERVED, retrying without...
2019-06-21 18:03:01.236 15047-15064/com.example.myapplicationjava D/OpenGLRenderer: Swap behavior 0
2019-06-21 18:03:01.255 15047-15064/com.example.myapplicationjava D/EGL_emulation: eglCreateContext: 0x9e3f39e0: maj 2 min 0 rcv 2
2019-06-21 18:03:01.306 15047-15064/com.example.myapplicationjava D/EGL_emulation: eglMakeCurrent: 0x9e3f39e0: ver 2 0 (tinfo 0x9e3909e0)
2019-06-21 18:03:01.333 15047-15047/com.example.myapplicationjava W/art: Before Android 4.1, method int androidx.appcompat.widget.DropDownListView.lookForSelectablePosition(int, boolean) would have incorrectly overridden the package-private method in android.widget.ListView
2019-06-21 18:03:01.342 15047-15064/com.example.myapplicationjava D/EGL_emulation: eglMakeCurrent: 0x9e3f39e0: ver 2 0 (tinfo 0x9e3909e0)
2019-06-21 18:03:08.480 15047-15047/com.example.myapplicationjava I/System.out: question
2019-06-21 18:03:08.480 15047-15047/com.example.myapplicationjava I/System.out: A. answer1
2019-06-21 18:03:08.480 15047-15047/com.example.myapplicationjava I/System.out: B. answer2
2019-06-21 18:03:08.480 15047-15047/com.example.myapplicationjava I/System.out: C. answer3
2019-06-21 18:03:08.481 15047-15047/com.example.myapplicationjava D/AndroidRuntime: Shutting down VM
--------- beginning of crash
2019-06-21 18:03:08.481 15047-15047/com.example.myapplicationjava E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.myapplicationjava, PID: 15047
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.myapplicationjava/com.example.myapplicationjava.questions}: java.util.NoSuchElementException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
Caused by: java.util.NoSuchElementException
at java.util.Scanner.throwFor(Scanner.java:874)
at java.util.Scanner.next(Scanner.java:1388)
at com.example.myapplicationjava.questions.onCreate(questions.java:47)
at android.app.Activity.performCreate(Activity.java:6662)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
我可能会尝试删除整个 system.next 内容，并尝试在进行更多谷歌搜索后以其他方式查看问题。感谢到目前为止的所有建议。
最佳答案
你的问题是你试图在 Scanner 对象上调用 input.next()，而不检查它是否真的还有任何其他元素，这就是你得到 NoSuchElementException 的原因。试试这个:
if(input.hasNext()) {
String ans = input.next();
if(ans.equalsIgnoreCase(curQuest.correctOption)) {
System.out.println("Correct");
correct++;
} else {
System.out.println("incorrect");
}
}
这不会使其崩溃，您可以在 Logcat 中看到日志，但它仍然无法按照我想象的方式运行。
关于java - 执行某些代码时，我在 android studio 中的应用程序崩溃，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/56706070/