[英]Why doesn't try-Catch work as it's supposed to be?
我想做一个try-catch块。
在我的try块中,有一个方法可以检查是否按下了radioButton
,如果这样,它应该设置一个枚举并前进,如果没有按下radioButton
,则应引发NullPointerException
并关闭应用程序(其中有一些额外的功能,还没有完成,所以我暂时将其删除了)。
到目前为止,我看到的所有内容都不适合我的问题,因为他们只是忘了一个陷阱,或者他们拼错了一种方法或类似的东西。
如果我不按我的应用程序关闭一个radioButton
它会起作用,但是如果我按一个radioButton
我的应用程序再次关闭,但是它应该转到我的下一个布局并设置一个枚举(取决于按下哪个radioButton
。
我的Java代码:
public void setKnowledge() {
setContentView(R.layout.knowledge_level);
Button checking = (Button) findViewById(R.id.buttonChecking);
checking.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v) {
try {
checkSelection();
setContentView(R.layout.category_auswahl);
}catch(NullPointerException n) {
android.os.Process.killProcess(android.os.Process.myPid());
System.exit(0);
}
}
});
}
public knowledge checkSelection() {
RadioButton rbNoob = (RadioButton) findViewById(R.id.radioButtonNoob);
RadioButton rbBeginner = (RadioButton) findViewById(R.id.radioButtonBeginner);
RadioButton rbAdvanced = (RadioButton) findViewById(R.id.radioButtonAdv);
RadioButton rbPro = (RadioButton) findViewById(R.id.radioButtonPro);
RadioButton rbGrandMaster = (RadioButton) findViewById(R.id.radioButtonGM);
advertisment();
if(rbNoob.isChecked()) {
return knowledge.NOOB;
}
else if(rbBeginner.isChecked()) {
return knowledge.BEGINNER;
}
else if(rbAdvanced.isChecked()) {
return knowledge.ADVANCED;
}
else if(rbPro.isChecked()) {
return knowledge.PRO;
}
else if(rbGrandMaster.isChecked()) {
return knowledge.GM;
}
return null;
}
我的XML :(编辑:knowledge_level.xml)
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#081929" >
<RadioGroup
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="32dp"
app:layout_constraintTop_toBottomOf="@+id/testWissenstandText"
android:layout_marginLeft="8dp"
app:layout_constraintLeft_toLeftOf="parent"
android:id="@+id/radioGroup"
app:layout_constraintRight_toLeftOf="@+id/buttonChecking"
android:layout_marginRight="8dp"
app:layout_constraintHorizontal_bias="0.538">
<RadioButton
android:id="@+id/radioButtonNoob"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="0dp"
android:layout_marginRight="0dp"
android:layout_marginTop="8dp"
android:checked="false"
android:text="Keine Vorkenntnisse"
android:textAlignment="center"
android:textColor="#E0E0E0"
android:textSize="18sp"
android:textStyle="bold"
app:layout_constraintHorizontal_bias="0.505"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toLeftOf="@+id/buttonChecking"
app:layout_constraintTop_toBottomOf="@+id/testWissenstandText"/>
<RadioButton
android:id="@+id/radioButtonBeginner"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="0dp"
android:layout_marginRight="0dp"
android:layout_marginTop="8dp"
android:checked="false"
android:text="Anfänger"
android:textAlignment="center"
android:textColor="#E0E0E0"
android:textSize="18sp"
android:textStyle="bold"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toLeftOf="@+id/radioButtonNoob"
app:layout_constraintRight_toRightOf="@+id/radioButtonNoob"
app:layout_constraintTop_toBottomOf="@+id/radioButtonNoob"/>
<RadioButton
android:id="@+id/radioButtonAdv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="0dp"
android:layout_marginRight="0dp"
android:layout_marginTop="8dp"
android:text="Fortgeschrittener"
android:textAlignment="center"
android:textColor="#E0E0E0"
android:textSize="18sp"
android:textStyle="bold"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toLeftOf="@+id/radioButtonBeginner"
app:layout_constraintRight_toRightOf="@+id/radioButtonBeginner"
app:layout_constraintTop_toBottomOf="@+id/radioButtonBeginner"/>
<RadioButton
android:id="@+id/radioButtonPro"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="0dp"
android:layout_marginRight="0dp"
android:layout_marginTop="8dp"
android:text="Pro"
android:textAlignment="center"
android:textColor="#E0E0E0"
android:textSize="18sp"
android:textStyle="bold"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toLeftOf="@+id/radioButtonAdv"
app:layout_constraintRight_toRightOf="@+id/radioButtonAdv"
app:layout_constraintTop_toBottomOf="@+id/radioButtonAdv"/>
<RadioButton
android:id="@+id/radioButtonGM"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="0dp"
android:layout_marginRight="0dp"
android:layout_marginTop="8dp"
android:text='"Grand Master"'
android:textAlignment="center"
android:textColor="#E0E0E0"
android:textSize="18sp"
android:textStyle="bold"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toLeftOf="@+id/radioButtonPro"
app:layout_constraintRight_toRightOf="@+id/radioButtonPro"
app:layout_constraintTop_toBottomOf="@+id/radioButtonPro"/>
</RadioGroup>
<ImageView
android:id="@+id/kastenKnowledge"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="16dp"
app:layout_constraintHorizontal_bias="0.517"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="@drawable/kasten"/>
<TextView
android:id="@+id/testWissenstandHeader"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:text="Dein Wissensstand?"
android:textAlignment="center"
android:textColor="#511613"
android:textSize="32sp"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="@+id/kastenKnowledge"
app:layout_constraintLeft_toLeftOf="@+id/kastenKnowledge"
app:layout_constraintRight_toRightOf="@+id/kastenKnowledge"
app:layout_constraintTop_toTopOf="@+id/kastenKnowledge"/>
<TextView
android:id="@+id/testWissenstandText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="16dp"
android:layout_marginStart="16dp"
android:layout_marginTop="24dp"
android:text='Wie würdest du deinen Wissenstand\nbezüglich dem Spieleinhalt\nvon "Overwatch" beurteilen?'
android:textAlignment="center"
android:textColor="#E0E0E0"
android:textSize="20sp"
app:layout_constraintHorizontal_bias="0.512"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="@+id/testWissenstandHeader"/>
<Button
android:id="@+id/buttonChecking"
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_marginEnd="16dp"
android:layout_marginStart="0dp"
android:background="@drawable/button_box"
android:text="C\nL\nI\nC\nK"
android:textAllCaps="false"
android:textColor="#511613"
android:textSize="16sp"
android:textStyle="bold"
app:layout_constraintRight_toRightOf="parent"
android:layout_marginRight="16dp"
app:layout_constraintBottom_toBottomOf="@+id/radioGroup"
android:layout_marginBottom="8dp"
app:layout_constraintTop_toTopOf="@+id/radioGroup"
android:layout_marginTop="8dp"
app:layout_constraintVertical_bias="0.5"/>
<TextView
android:id="@+id/knowledgeHint"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="0dp"
android:layout_marginRight="0dp"
android:text="Wenn du einen Wissenstand\nfestgelegt hast, drücke den\nKnopf daneben!"
android:textAlignment="center"
android:textColor="#FF4400"
android:textSize="20sp"
android:textStyle="bold|italic"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
android:layout_marginTop="32dp"
app:layout_constraintTop_toBottomOf="@+id/radioGroup"/>
</android.support.constraint.ConstraintLayout>
错误消息:
08-14 21:01:26.469 4312-4312/? I/Process: Sending signal. PID: 4312 SIG: 9
08-14 21:01:26.470 1521-1590/system_process W/AudioTrack: AUDIO_OUTPUT_FLAG_FAST denied by client
--------- beginning of system
08-14 21:01:26.476 1521-1773/system_process I/WindowState: WIN DEATH: Window{ab30a43 u0 com.example.alexander.hashtagnevereverbuggy/com.example.alexander.hashtagnevereverbuggy.MainActivity}
08-14 21:01:26.480 1521-2538/system_process I/ActivityManager: Process com.example.alexander.hashtagnevereverbuggy (pid 4312) has died
08-14 21:01:26.480 1521-2538/system_process W/ActivityManager: Force removing ActivityRecord{ed88b90 u0 com.example.alexander.hashtagnevereverbuggy/.MainActivity t137}: app died, no saved state
08-14 21:01:26.491 1128-1128/? W/SurfaceFlinger: couldn't log to binary event log: overflow.
08-14 21:01:27.104 1776-1958/com.android.launcher D/EGL_emulation: eglMakeCurrent: 0x7fd4ff628200: ver 2 0
08-14 21:01:27.135 1521-1773/system_process W/InputMethodManagerService: Got RemoteException sending setActive(false) notification to pid 4312 uid 10058
删除setContentView(R.layout.category_auswahl);
内部onclick侦听器。
更改:
public knowledge checkSelection() {
RadioButton rbNoob = (RadioButton) findViewById(R.id.radioButtonNoob);
RadioButton rbBeginner = (RadioButton) findViewById(R.id.radioButtonBeginner);
// etc
else if(rbGrandMaster.isChecked()) {
return knowledge.GM;
}
return null;
}
对此:
public knowledge checkSelection() {
RadioButton rbNoob = (RadioButton) findViewById(R.id.radioButtonNoob);
RadioButton rbBeginner = (RadioButton) findViewById(R.id.radioButtonBeginner);
// etc
else if(rbGrandMaster.isChecked()) {
return knowledge.GM;
}
throw new NullPointerException();
}
try {
if (checkSelection() == null) {
throw new NullPointerException("checkSelection is null");
}
setContentView(R.layout.category_auswahl);
}catch(NullPointerException n) {
android.os.Process.killProcess(android.os.Process.myPid());
System.exit(0);
}
伙计,try-catch不是您在此代码中遇到的问题。
它工作正常并关闭您的应用: 08-14 21:01:26.469 4312-4312/? I/Process: Sending signal. PID: 4312 SIG: 9
08-14 21:01:26.469 4312-4312/? I/Process: Sending signal. PID: 4312 SIG: 9
您没有打印NPE,这就是为什么在日志中没有它的原因。
您需要使用片段而不是设置新的内容视图。
您永远不需要Android中的System.exit(0),因为它与系统相对,您必须使用Activity类中的finish 。
您可以将onClickListener设置为RadioGroup而不是使用检查按钮,并且每次选择时都会获取事件,因此可以继续下一个Screen(Activity或Fragment,但是没有理由使用另一个setContentView)。
这是有关setContentView的很好的解释: Android:更改布局时多次使用setContentView是不好的吗?
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