以下是一个简单的SQLite示例的MainActivity。该应用程序在发布时崩溃。以下是错误（粗体）：
11-10 10:40:41.243 1773-1773/? I/art: Late-enabling -Xcheck:jni
11-10 10:40:41.286 1773-1773/com.mytestfyp.ahmed.database V/Theme: ColorMode:com.mytestfyp.ahmed.database is false
11-10 10:40:41.328 1773-1773/com.mytestfyp.ahmed.database W/art: Failed execv(/system/bin/dex2oat --runtime-arg -classpath --runtime-arg --instruction-set=arm64 --instruction-set-features=smp,a53 --runtime-arg -Xrelocate --boot-image=/system/framework/boot.art --runtime-arg -Xms64m --runtime-arg -Xmx512m --instruction-set-variant=generic --instruction-set-features=default --dex-file=/data/app/com.mytestfyp.ahmed.database-1/split_lib_dependencies_apk.apk --oat-file=/data/dalvik-cache/arm64/data@app@com.mytestfyp.ahmed.database-1@split_lib_dependencies_apk.apk@classes.dex) because non-0 exit status
11-10 10:40:41.473 1773-1773/com.mytestfyp.ahmed.database W/art: Failed execv(/system/bin/dex2oat --runtime-arg -classpath --runtime-arg --instruction-set=arm64 --instruction-set-features=smp,a53 --runtime-arg -Xrelocate --boot-image=/system/framework/boot.art --runtime-arg -Xms64m --runtime-arg -Xmx512m --instruction-set-variant=generic --instruction-set-features=default --dex-file=/data/app/com.mytestfyp.ahmed.database-1/split_lib_slice_0_apk.apk --oat-file=/data/dalvik-cache/arm64/data@app@com.mytestfyp.ahmed.database-1@split_lib_slice_0_apk.apk@classes.dex) because non-0 exit status
11-10 10:40:41.513 1773-1773/com.mytestfyp.ahmed.database W/art: Failed execv(/system/bin/dex2oat --runtime-arg -classpath --runtime-arg --instruction-set=arm64 --instruction-set-features=smp,a53 --runtime-arg -Xrelocate --boot-image=/system/framework/boot.art --runtime-arg -Xms64m --runtime-arg -Xmx512m --instruction-set-variant=generic --instruction-set-features=default --dex-file=/data/app/com.mytestfyp.ahmed.database-1/split_lib_slice_1_apk.apk --oat-file=/data/dalvik-cache/arm64/data@app@com.mytestfyp.ahmed.database-1@split_lib_slice_1_apk.apk@classes.dex) because non-0 exit status
11-10 10:40:41.553 1773-1773/com.mytestfyp.ahmed.database W/art: Failed execv(/system/bin/dex2oat --runtime-arg -classpath --runtime-arg --instruction-set=arm64 --instruction-set-features=smp,a53 --runtime-arg -Xrelocate --boot-image=/system/framework/boot.art --runtime-arg -Xms64m --runtime-arg -Xmx512m --instruction-set-variant=generic --instruction-set-features=default --dex-file=/data/app/com.mytestfyp.ahmed.database-1/split_lib_slice_2_apk.apk --oat-file=/data/dalvik-cache/arm64/data@app@com.mytestfyp.ahmed.database-1@split_lib_slice_2_apk.apk@classes.dex) because non-0 exit status
11-10 10:40:41.593 1773-1773/com.mytestfyp.ahmed.database W/art: Failed execv(/system/bin/dex2oat --runtime-arg -classpath --runtime-arg --instruction-set=arm64 --instruction-set-features=smp,a53 --runtime-arg -Xrelocate --boot-image=/system/framework/boot.art --runtime-arg -Xms64m --runtime-arg -Xmx512m --instruction-set-variant=generic --instruction-set-features=default --dex-file=/data/app/com.mytestfyp.ahmed.database-1/split_lib_slice_3_apk.apk --oat-file=/data/dalvik-cache/arm64/data@app@com.mytestfyp.ahmed.database-1@split_lib_slice_3_apk.apk@classes.dex) because non-0 exit status
11-10 10:40:41.631 1773-1773/com.mytestfyp.ahmed.database W/art: Failed execv(/system/bin/dex2oat --runtime-arg -classpath --runtime-arg --instruction-set=arm64 --instruction-set-features=smp,a53 --runtime-arg -Xrelocate --boot-image=/system/framework/boot.art --runtime-arg -Xms64m --runtime-arg -Xmx512m --instruction-set-variant=generic --instruction-set-features=default --dex-file=/data/app/com.mytestfyp.ahmed.database-1/split_lib_slice_4_apk.apk --oat-file=/data/dalvik-cache/arm64/data@app@com.mytestfyp.ahmed.database-1@split_lib_slice_4_apk.apk@classes.dex) because non-0 exit status
11-10 10:40:41.669 1773-1773/com.mytestfyp.ahmed.database W/art: Failed execv(/system/bin/dex2oat --runtime-arg -classpath --runtime-arg --instruction-set=arm64 --instruction-set-features=smp,a53 --runtime-arg -Xrelocate --boot-image=/system/framework/boot.art --runtime-arg -Xms64m --runtime-arg -Xmx512m --instruction-set-variant=generic --instruction-set-features=default --dex-file=/data/app/com.mytestfyp.ahmed.database-1/split_lib_slice_5_apk.apk --oat-file=/data/dalvik-cache/arm64/data@app@com.mytestfyp.ahmed.database-1@split_lib_slice_5_apk.apk@classes.dex) because non-0 exit status
11-10 10:40:41.706 1773-1773/com.mytestfyp.ahmed.database W/art: Failed execv(/system/bin/dex2oat --runtime-arg -classpath --runtime-arg --instruction-set=arm64 --instruction-set-features=smp,a53 --runtime-arg -Xrelocate --boot-image=/system/framework/boot.art --runtime-arg -Xms64m --runtime-arg -Xmx512m --instruction-set-variant=generic --instruction-set-features=default --dex-file=/data/app/com.mytestfyp.ahmed.database-1/split_lib_slice_6_apk.apk --oat-file=/data/dalvik-cache/arm64/data@app@com.mytestfyp.ahmed.database-1@split_lib_slice_6_apk.apk@classes.dex) because non-0 exit status
11-10 10:40:41.747 1773-1773/com.mytestfyp.ahmed.database W/art: Failed execv(/system/bin/dex2oat --runtime-arg -classpath --runtime-arg --instruction-set=arm64 --instruction-set-features=smp,a53 --runtime-arg -Xrelocate --boot-image=/system/framework/boot.art --runtime-arg -Xms64m --runtime-arg -Xmx512m --instruction-set-variant=generic --instruction-set-features=default --dex-file=/data/app/com.mytestfyp.ahmed.database-1/split_lib_slice_7_apk.apk --oat-file=/data/dalvik-cache/arm64/data@app@com.mytestfyp.ahmed.database-1@split_lib_slice_7_apk.apk@classes.dex) because non-0 exit status
11-10 10:40:41.788 1773-1773/com.mytestfyp.ahmed.database W/art: Failed execv(/system/bin/dex2oat --runtime-arg -classpath --runtime-arg --instruction-set=arm64 --instruction-set-features=smp,a53 --runtime-arg -Xrelocate --boot-image=/system/framework/boot.art --runtime-arg -Xms64m --runtime-arg -Xmx512m --instruction-set-variant=generic --instruction-set-features=default --dex-file=/data/app/com.mytestfyp.ahmed.database-1/split_lib_slice_8_apk.apk --oat-file=/data/dalvik-cache/arm64/data@app@com.mytestfyp.ahmed.database-1@split_lib_slice_8_apk.apk@classes.dex) because non-0 exit status
11-10 10:40:41.836 1773-1773/com.mytestfyp.ahmed.database W/art: Failed execv(/system/bin/dex2oat --runtime-arg -classpath --runtime-arg --instruction-set=arm64 --instruction-set-features=smp,a53 --runtime-arg -Xrelocate --boot-image=/system/framework/boot.art --runtime-arg -Xms64m --runtime-arg -Xmx512m --instruction-set-variant=generic --instruction-set-features=default --dex-file=/data/app/com.mytestfyp.ahmed.database-1/split_lib_slice_9_apk.apk --oat-file=/data/dalvik-cache/arm64/data@app@com.mytestfyp.ahmed.database-1@split_lib_slice_9_apk.apk@classes.dex) because non-0 exit status
11-10 10:40:41.837 1773-1773/com.mytestfyp.ahmed.database W/System: ClassLoader referenced unknown path: /data/app/com.mytestfyp.ahmed.database-1/lib/arm64
11-10 10:40:41.840 1773-1773/com.mytestfyp.ahmed.database I/InstantRun: starting instant run server: is main process
11-10 10:40:41.843 1773-1773/com.mytestfyp.ahmed.database I/Instrumentation: android.app.Application@103d181 onCreate begin
11-10 10:40:41.843 1773-1773/com.mytestfyp.ahmed.database I/Instrumentation: android.app.Application@103d181 onCreate in 0ms
11-10 10:40:41.900 1773-1773/com.mytestfyp.ahmed.database 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$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
11-10 10:40:42.003 1773-1773/com.mytestfyp.ahmed.database D/AndroidRuntime: Shutting down VM
11-10 10:40:42.003 1773-1773/com.mytestfyp.ahmed.database E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.mytestfyp.ahmed.database, PID: 1773
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mytestfyp.ahmed.database/com.mytestfyp.ahmed.database.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.LinearLayout.setOnLongClickListener(android.view.View$OnLongClickListener)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2452)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2535)
at android.app.ActivityThread.access$900(ActivityThread.java:155)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1380)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:152)
at android.app.ActivityThread.main(ActivityThread.java:5497)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.LinearLayout.setOnLongClickListener(android.view.View$OnLongClickListener)' on a null object reference
**at com.mytestfyp.ahmed.database.MainActivity.displayAllRecords(MainActivity.java:143)
at com.mytestfyp.ahmed.database.MainActivity.onCreate(MainActivity.java:45)**
at android.app.Activity.performCreate(Activity.java:6289)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2405)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2535)
at android.app.ActivityThread.access$900(ActivityThread.java:155)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1380)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:152)
at android.app.ActivityThread.main(ActivityThread.java:5497)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
11-10 10:40:42.005 1773-1773/com.mytestfyp.ahmed.database D/AppTracker: App Event: crash
11-10 10:40:44.108 1773-1773/com.mytestfyp.ahmed.database I/Process: Sending signal. PID: 1773 SIG: 9
以下是MainActivity的代码：
package com.mytestfyp.ahmed.database;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.HashMap;
public class MainActivity extends AppCompatActivity
{
Button btnAddNewRecord;
SQLiteHelper sQLiteHelper;
android.widget.LinearLayout parentLayout;
LinearLayout layoutDisplayPeople;
TextView tvNoRecordsFound;
private String rowID = null;
private ArrayList<HashMap<String, String>> tableData = new ArrayList<HashMap<String, String>>();
private class Holder
{
TextView tvFullName;
String name;
String age;
}
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
getAllWidgets();
sQLiteHelper = new SQLiteHelper(MainActivity.this);
bindWidgetsWithEvent();
displayAllRecords();
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data)
{
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == RESULT_OK)
{
//firstname & lastname
String name = data.getStringExtra(Constants.NAME);
String age = data.getStringExtra(Constants.AGE);
ContactModel contact = new ContactModel();
contact.setName(name);
contact.setAge(age);
if (requestCode == Constants.ADD_RECORD)
{
sQLiteHelper.insertRecord(contact);
}
else if (requestCode == Constants.UPDATE_RECORD)
{
contact.setID(rowID);
sQLiteHelper.updateRecord(contact);
}
displayAllRecords();
}
}
private void getAllWidgets()
{
btnAddNewRecord = (Button) findViewById(R.id.btnAddNewRecord);
parentLayout = (LinearLayout) findViewById(R.id.parentLayout);
tvNoRecordsFound = (TextView) findViewById(R.id.tvNoRecordsFound);
}
private void bindWidgetsWithEvent()
{
btnAddNewRecord.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
onAddRecord();
}
});
}
private void onAddRecord()
{
Intent intent = new Intent(MainActivity.this, TableManipulationActivity.class);
intent.putExtra(Constants.DML_TYPE, Constants.ADD_RECORD);
startActivityForResult(intent, Constants.ADD_RECORD);
}
private void onUpdateRecord(String name, String age)
{
Intent intent = new Intent(MainActivity.this, TableManipulationActivity.class);
intent.putExtra(Constants.NAME, name);
intent.putExtra(Constants.AGE, age);
intent.putExtra(Constants.DML_TYPE, Constants.UPDATE);
startActivityForResult(intent, Constants.UPDATE_RECORD);
}
private void displayAllRecords()
{
LinearLayout inflateParentView;
parentLayout.removeAllViews();
ArrayList<ContactModel> contacts = sQLiteHelper.getAllRecords();
if (contacts.size() > 0)
{
tvNoRecordsFound.setVisibility(View.GONE);
ContactModel contactModel;
for (int i = 0; i < contacts.size(); i++)
{
contactModel = contacts.get(i);
final Holder holder = new Holder();
final View view = LayoutInflater.from(this).inflate(R.layout.inflate_record, null);
inflateParentView = (LinearLayout) findViewById(R.id.inflateParentView);
holder.tvFullName = (TextView) view.findViewById(R.id.tvFullName);
view.setTag(contactModel.getID());
holder.name = contactModel.getName();
holder.age = contactModel.getAge();
String personData = holder.name + " " +holder.age;
holder.tvFullName.setText(personData);
final CharSequence[] items = {Constants.UPDATE, Constants.DELETE};
inflateParentView.setOnLongClickListener(new View.OnLongClickListener()
{
@Override
public boolean onLongClick(View v)
{
AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
builder.setItems(items, new DialogInterface.OnClickListener()
{
@Override
public void onClick(DialogInterface dialog, int which)
{
if (which == 0)
{
rowID = view.getTag().toString();
onUpdateRecord(holder.name, holder.age);
}
else
{
AlertDialog.Builder deleteDialogOK = new AlertDialog.Builder(MainActivity.this);
deleteDialogOK.setTitle("Delete Person ?");
deleteDialogOK.setPositiveButton("OK", new DialogInterface.OnClickListener()
{
@Override
public void onClick(DialogInterface dialog, int which)
{
ContactModel contact = new ContactModel();
contact.setID(view.getTag().toString());
sQLiteHelper.deleteRecord(contact);
displayAllRecords();
}
});
deleteDialogOK.setNegativeButton("Cancel", new DialogInterface.OnClickListener()
{
@Override
public void onClick(DialogInterface dialog, int which)
{
}
});
deleteDialogOK.show();
}
}
});
AlertDialog alertDialog = builder.create();
alertDialog.show();
return true;
}
});
parentLayout.addView(view);
}
}
else
{
tvNoRecordsFound.setVisibility(View.VISIBLE);
}
}
}
以下是相关的XML：
activitymain.xml：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical"
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=".MainActivity">
<ScrollView
android:id="@+id/scrollViewDisplay"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="1">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<LinearLayout
android:id="@+id/layoutDisplayPeople"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:text="@string/people"
android:textColor="@color/color_black"
android:textSize="25sp"
android:textStyle="bold" />
<TextView
android:id="@+id/tvNoRecordsFound"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="15dp"
android:layout_marginTop="15dp"
android:gravity="center"
android:text="@string/nrf"
android:textColor="@color/color_black"
android:textSize="15sp" />
<LinearLayout
android:id="@+id/parentLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"/>
</LinearLayout>
</LinearLayout>
</ScrollView>
<Button
android:id="@+id/btnAddNewRecord"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@color/color_blue"
android:text="@string/add"
android:textColor="@color/color_white"
android:textStyle="bold" />
</LinearLayout>
inflate_record.xml：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
android:gravity="center_horizontal">
<LinearLayout
android:id="@+id/inflateParentView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center">
<TextView
android:id="@+id/tvFullName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="15dp"
android:layout_marginTop="15dp"
android:layout_marginStart="15dp"
android:layout_weight="1"
android:text="@string/name"
android:textSize="15sp"
android:gravity="start"
android:textColor="@color/color_black"
android:textStyle="bold" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="2dp"
android:background="@color/color_grey"/>
</LinearLayout>
请帮助我。提前谢谢！
答案 0 :(得分：1)
您的应用崩溃是因为在尝试在 NULL inflateParentView上调用setOnLongClickListener()时出现NullPointerException。确保视图不为空。
答案 1 :(得分：1)
inflateParentView为null，因为它未实例化。在activity中调用findViewById（）将在特定活动布局中找到id。您需要从自定义布局中找到该视图。因此更改此行。
inflateParentView = (LinearLayout) findViewById(R.id.inflateParentView);
到
inflateParentView = (LinearLayout) view.findViewById(R.id.inflateParentView);
答案 2 :(得分：1)
试试这个：
inflateParentView = (LinearLayout)view.findViewById(R.id.inflateParentView);。
NullPointerException您获得了inflateParentView。这是因为您试图从活动布局而不是从膨胀的视图中查找视图。希望它有所帮助：）