我的应用程序在启动时崩溃 [英] My application crashes on startup
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问题描述
我的应用程序在启动时崩溃，没有显示任何错误。
我找不到原因。我尝试了很多解决方案，但徒劳无功
这里是MainActivity.java
package com.example.android.mycourses;
导入android.os.Bundle;
导入android.support.v7.app.AppCompatActivity;
导入android.widget.CheckBox;
导入android.widget.CompoundButton;
导入android.widget.ListView;
导入android.widget.TextView;
import com.google.firebase.database.ChildEventListener;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import java.util.ArrayList;
$ b $ public class MainActivity extends AppCompatActivity {
private FirebaseDatabase mfirebasedatabase; //访问数据库
private DatabaseReference mDatabase; //类引用数据库的特定部分
private ChildEventListener mchildEventListener; //从数据库读取
TextView courseTV;
CheckBox复选框;
CourseAdapter适配器;
@Override
protected void onCreate（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）;
setContentView（R.layout.activity_main）;
mfirebasedatabase = FirebaseDatabase.getInstance（）; //实例化数据库（这是数据库的访问点）
mDatabase = mfirebasedatabase.getReference（）。child（courses） ;
courseTV =（TextView）findViewById（R.id.messageTextView）;
populateUsersList（）;
checkbox =（CheckBox）findViewById（R.id.checkbox）;
checkbox.setOnCheckedChangeListener（new CompoundButton.OnCheckedChangeListener（）
{
public void onCheckedChanged（CompoundButton buttonView，boolean isChecked）
{
if（isChecked）
{
//保存在数据库中
课程cc = new Course（courseTV.getText（）。toString（））;
mDatabase.push（）。setValue（cc）;
}
else if（！isChecked）{
//从数据库中删除
}
}
}）;
mchildEventListener = new ChildEventListener（）{
@Override $ b $ public void onChildAdded（DataSnapshot dataSnapshot，String s）{
Course c = dataSnapshot.getValue（Course.class）;
adapter.add（c）;
$ b @Override
public void onChildChanged（DataSnapshot dataSnapshot，String s）{
}
@Override
public void onChildRemoved（DataSnapshot dataSnapshot）{
$ b @Override
public void onChildMoved（DataSnapshot dataSnapshot，String s）{
}
@Override
public void onCancelled（DatabaseError databaseError）{
};
mDatabase.addChildEventListener（mchildEventListener）;
$ b private void populateUsersList（）{
//构造数据源
ArrayList< Course> arrayOfUsers = Course.getCourses（）;
//创建适配器将数组转换为视图
CourseAdapter adapter = new CourseAdapter（this，arrayOfUsers）;
//将适配器连接到一个ListView
ListView listView =（ListView）findViewById（R.id.listView）;
listView.setAdapter（adapter）;
$ / code $ / pre
$ b $ p 这里是activity_main.xml <？xml version =1.0encoding =utf-8？>
< RelativeLayout
xmlns：android =http://schemas.android.com/apk/res/android
xmlns：tools =http://schemas.android.com / tools
android：layout_width =match_parent
android：layout_height =match_parent
android：paddingBottom =@ dimen / activity_vertical_margin
android：paddingLeft =@ dimen / activity_horizontal_margin
android：paddingRight =@ dimen / activity_horizontal_margin
android：paddingTop =@ dimen / activity_vertical_margin
tools：context =com.example.android.mycourses.MainActivity >
< ListView
android：layout_width =wrap_content
android：layout_height =wrap_content
android：id =@ + id / listView> < /&的ListView GT;
< / RelativeLayout>
这里是item_message.xml
<？xml version =1.0encoding =utf-8？>
< RelativeLayout xmlns：android =http://schemas.android.com/apk/res/android
xmlns：tools =http://schemas.android.com/tools
android：layout_width =match_parent
android：layout_height =wrap_content
android：layout_marginLeft =@ dimen / activity_horizontal_margin
android：layout_marginStart =@ dimen / activity_horizontal_margin
android：orientation =vertical>
TextView $ b $ android android：layout_height =wrap_content
$ $ b android：layout_weight =0
android：textAppearance =？android：attr / textAppearanceLarge
tools：text =course/>
android：layout_height =wrap_content
android：id =@ + id / checkbox
android： layout_alignRight = @ + ID / messageTextView/>
< / RelativeLayout>
这里是日志显示给我的内容
02-16 16：57：52.515 9095-9095 /？ I / art：延迟启用-Xcheck：jni
02-16 16：57：52.647 9095-9095 / com.example.android.mycourses W / System：ClassLoader引用未知路径：/ data / app / com。 example.android.mycourses-1 / lib / arm64
02-16 16：57：52.686 9095-9095 / com.example.android.mycourses I / FA：App measurement is started up，version：10084
02-16 16：57：52.686 9095-9095 / com.example.android.mycourses I / FA：启用调试日志记录运行：adb shell setprop log.tag.FA VERBOSE
02-16 16:57： 52.703 9095-9095 / com.example.android.mycourses I / FA：启用更快的调试模式事件记录运行：
adb shell setprop debug.firebase.analytics.app com.example.android.mycourses
02-16 16：57：52.712 9095-9095 / com.example.android.mycourses I / HwCust：找到类android.app.HwCustAlarmManagerImpl的构造函数b $ b 02-16 16：57：52.722 9095-9095 / com。 example.android.mycourses I / FirebaseInitProvider：FirebaseApp初始化成功ssful
02-16 16：57：52.775 9095-9095 / com.example.android.mycourses W / art：在Android 4.1之前，方法android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter android.graphics.PorterDuffColorFilter，android.content.res.ColorStateList，android.graphics.PorterDuff $ Mode）将不正确地覆盖android.graphics.drawable.Drawable中的包私有方法
02-16 16:57： 52.894 9095-9095 / com.example.android.mycourses I / DynamiteModule：考虑本地模块com.google.android.gms.firebase_database：4和远程模块com.google.android.gms.firebase_database：5
02- 16 16：57：52.894 9095-9095 / com.example.android.mycourses I / DynamiteModule：选定的远程版本com.google.android.gms.firebase_database，版本> = 5
02-16 16:57 ：52.911 9095-9095 / com.example.android.mycourses W / System：ClassLoader引用未知路径：/data/user/0/com.google.android.gms/app_chimera/m/00000007/n/arm64-v8a
02-16 16：57：52.967 9095-9144 / com.example.android.mycourses我/系统：core_booster，getBoosterConfig = false
02-16 16：57：52.989 9095-9095 / com。 example.android.mycourses I / Process：发送信号。 PID：9095 SIG：9
解决方案如果你想让应用程序运行的话，那就不要使用Activity了。
$ b $ pre $ course $ =（TextView）findViewById（R.id.messageTextView） ;
checkbox =（CheckBox）findViewById（R.id.checkbox）;
checkbox.setOnCheckedChangeListener
这两个视图都不在activity_main里面
My app crashes on startup without showing any error.
I can't find why. I tried many solutions, but in vain
here is MainActivity.java
package com.example.android.mycourses;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.ListView;
import android.widget.TextView;
import com.google.firebase.database.ChildEventListener;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
private FirebaseDatabase mfirebasedatabase; //to access the database
private DatabaseReference mDatabase; //class references a specific part of the database
private ChildEventListener mchildEventListener; //to read from the database
TextView courseTV;
CheckBox checkbox;
CourseAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mfirebasedatabase=FirebaseDatabase.getInstance();//to instantiate the database(this is the access point to the database)
mDatabase=mfirebasedatabase.getReference().child("courses");
courseTV = (TextView) findViewById(R.id.messageTextView);
populateUsersList();
checkbox = ( CheckBox ) findViewById( R.id.checkbox );
checkbox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener()
{
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked)
{
if ( isChecked )
{
// save in database
Course cc=new Course(courseTV.getText().toString());
mDatabase.push().setValue(cc);
}
else if(!isChecked){
//remove from database
}
}
});
mchildEventListener =new ChildEventListener(){
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
Course c=dataSnapshot.getValue(Course.class);
adapter.add(c);
}
@Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
}
@Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
}
@Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
};
mDatabase.addChildEventListener(mchildEventListener);
}
private void populateUsersList() {
// Construct the data source
ArrayList<Course> arrayOfUsers = Course.getCourses();
// Create the adapter to convert the array to views
CourseAdapter adapter = new CourseAdapter(this, arrayOfUsers);
// Attach the adapter to a ListView
ListView listView = (ListView) findViewById(R.id.listView);
listView.setAdapter(adapter);
}
}
here is activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.android.mycourses.MainActivity">
<ListView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/listView"></ListView>
</RelativeLayout>
here is item_message.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="@dimen/activity_horizontal_margin"
android:layout_marginStart="@dimen/activity_horizontal_margin"
android:orientation="vertical">
<TextView
android:id="@+id/messageTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="0"
android:textAppearance="?android:attr/textAppearanceLarge"
tools:text="course" />
<CheckBox
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/checkbox"
android:layout_alignRight="@+id/messageTextView"/>
</RelativeLayout>
here is what the log shows to me
02-16 16:57:52.515 9095-9095/? I/art: Late-enabling -Xcheck:jni
02-16 16:57:52.647 9095-9095/com.example.android.mycourses W/System: ClassLoader referenced unknown path: /data/app/com.example.android.mycourses-1/lib/arm64
02-16 16:57:52.686 9095-9095/com.example.android.mycourses I/FA: App measurement is starting up, version: 10084
02-16 16:57:52.686 9095-9095/com.example.android.mycourses I/FA: To enable debug logging run: adb shell setprop log.tag.FA VERBOSE
02-16 16:57:52.703 9095-9095/com.example.android.mycourses I/FA: To enable faster debug mode event logging run:
adb shell setprop debug.firebase.analytics.app com.example.android.mycourses
02-16 16:57:52.712 9095-9095/com.example.android.mycourses I/HwCust: Constructor found for class android.app.HwCustAlarmManagerImpl
02-16 16:57:52.722 9095-9095/com.example.android.mycourses I/FirebaseInitProvider: FirebaseApp initialization successful
02-16 16:57:52.775 9095-9095/com.example.android.mycourses W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.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
02-16 16:57:52.894 9095-9095/com.example.android.mycourses I/DynamiteModule: Considering local module com.google.android.gms.firebase_database:4 and remote module com.google.android.gms.firebase_database:5
02-16 16:57:52.894 9095-9095/com.example.android.mycourses I/DynamiteModule: Selected remote version of com.google.android.gms.firebase_database, version >= 5
02-16 16:57:52.911 9095-9095/com.example.android.mycourses W/System: ClassLoader referenced unknown path: /data/user/0/com.google.android.gms/app_chimera/m/00000007/n/arm64-v8a
02-16 16:57:52.967 9095-9144/com.example.android.mycourses I/System: core_booster, getBoosterConfig = false
02-16 16:57:52.989 9095-9095/com.example.android.mycourses I/Process: Sending signal. PID: 9095 SIG: 9
解决方案
These need to be in the adapter, not the Activity if you want the app to run
courseTV = (TextView) findViewById(R.id.messageTextView);
checkbox = ( CheckBox ) findViewById( R.id.checkbox );
checkbox.setOnCheckedChangeListener
Neither of those views are inside activity_main
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