Android 当我单击底部工作表中的按钮时,我的应用程序停止
当我点击按钮时,我的应用程序停止。我创建了一个应用程序,当我在NavigationView中单击菜单时,它将显示一个底部工作表,然后在按钮工作表中有一个按钮,我应该单击该按钮打开一个DatePickerDialog。但在此之前,当配置文件(MainActivity)加载时,它将停止我的程序 从MainActivity到NavigationView再到Modal,一切都正常工作。。。直到我在Profile.java(MainActivity)中对其进行编码(下面的代码) 但是,当我删除上述代码行时,一切正常。请帮助我,我真的需要你们(大师) 这是我的个人资料(MainActivity.java) activity_profile.xmlAndroid 当我单击底部工作表中的按钮时,我的应用程序停止,android,nullpointerexception,Android,Nullpointerexception,当我点击按钮时,我的应用程序停止。我创建了一个应用程序,当我在NavigationView中单击菜单时,它将显示一个底部工作表,然后在按钮工作表中有一个按钮,我应该单击该按钮打开一个DatePickerDialog。但在此之前,当配置文件(MainActivity)加载时,它将停止我的程序 从MainActivity到NavigationView再到Modal,一切都正常工作。。。直到我在Profile.java(MainActivity)中对其进行编码(下面的代码) 但是,当我删除上述代码行时
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout
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:id="@+id/drawerlayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context=".Profile">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="@color/colorPrimary"
android:elevation="4dp"
android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
app:popupTheme="@style/ThemeOverlay.AppCompat.Light"></android.support.v7.widget.Toolbar>
<FrameLayout
android:id="@+id/fragment_container"
android:layout_width="match_parent"
android:layout_height="match_parent"></FrameLayout>
<ImageView
android:id="@+id/imPerson"
android:layout_width="66dp"
android:layout_height="62dp"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_marginStart="10dp"
android:layout_marginTop="59dp"
app:srcCompat="@drawable/profile" />
<TextView
android:id="@+id/txtFullname"
android:layout_width="274dp"
android:layout_height="wrap_content"
android:layout_alignTop="@+id/imPerson"
android:layout_marginStart="6dp"
android:layout_marginTop="0dp"
android:layout_toEndOf="@+id/imPerson"
android:text="John Bryan Cantiveros"
android:textColor="@color/white"
android:textSize="20dp"
android:textStyle="bold" />
<TextView
android:id="@+id/txtDesignation"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/txtFullname"
android:layout_alignStart="@+id/txtFullname"
android:layout_marginStart="1dp"
android:layout_marginTop="1dp"
android:text="Programmer"
android:textColor="@color/white" />
<TextView
android:id="@+id/txtBranch"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/txtDesignation"
android:layout_alignStart="@+id/txtFullname"
android:layout_marginStart="1dp"
android:layout_marginTop="0dp"
android:text="Lagao DJ Interprises"
android:textColor="@color/white" />
<View
android:layout_width="wrap_content"
android:layout_height="7dp"
android:layout_alignParentStart="true"
android:layout_alignParentEnd="true"
android:layout_marginStart="10dp"
android:layout_marginLeft="80dp"
android:layout_marginTop="130dp"
android:layout_marginEnd="10dp"
android:layout_marginRight="80dp"
android:layout_marginBottom="80dp"
android:background="@color/Yellow" />
<ListView
android:id="@+id/lvRemindersList"
android:layout_width="wrap_content"
android:layout_height="422dp"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_alignParentEnd="true"
android:layout_alignParentBottom="true"
android:layout_marginStart="10dp"
android:layout_marginTop="135dp"
android:layout_marginEnd="10dp"
android:layout_marginBottom="10dp"
android:background="@color/white" />
</RelativeLayout>
<android.support.design.widget.NavigationView
android:id="@+id/nav_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_gravity="start"
app:headerLayout="@layout/navigation_header"
app:menu="@menu/navigation_menu"/>
</android.support.v4.widget.DrawerLayout>
my modal_event.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:gravity="center_horizontal"
android:orientation="vertical"
android:padding="16dp">
<TextView
android:id="@+id/textView12"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Event" />
<EditText
android:id="@+id/txtEventName"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/textView12"
android:layout_centerHorizontal="true"
android:ems="10"
android:hint="Event Title"
android:inputType="textLongMessage" />
<EditText
android:id="@+id/txtWhere"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/textView15"
android:layout_alignStart="@+id/textView13"
android:ems="10"
android:hint="Event Location"
android:inputType="textLongMessage" />
<TextView
android:id="@+id/textView13"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/txtEventName"
android:layout_alignStart="@+id/txtEventName"
android:layout_marginTop="-1dp"
android:text="When" />
<EditText
android:id="@+id/txtDateTime"
android:layout_width="148dp"
android:layout_height="wrap_content"
android:layout_below="@+id/textView13"
android:layout_alignStart="@+id/textView12"
android:layout_marginStart="205dp"
android:layout_marginTop="0dp"
android:ems="10"
android:hint="Date/Time"
android:inputType="time"
android:textSize="15dp" />
<TextView
android:id="@+id/textView15"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/textView10"
android:layout_alignStart="@+id/textView13"
android:layout_marginStart="4dp"
android:text="Where" />
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignTop="@+id/textView12"
android:layout_alignParentEnd="true"
android:layout_marginTop="216dp"
android:layout_marginEnd="132dp"
android:text="Create" />
<Button
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignTop="@+id/button"
android:layout_alignParentEnd="true"
android:layout_marginTop="-1dp"
android:layout_marginEnd="15dp"
android:text="Close" />
<TextView
android:id="@+id/textView10"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/txtDateTime"
android:layout_alignParentStart="true"
android:layout_marginStart="0dp"
android:layout_marginEnd="21dp"
android:layout_toStartOf="@+id/txtDateTime"
android:text="at" />
<TextView
android:id="@+id/textView14"
android:layout_width="124dp"
android:layout_height="wrap_content"
android:layout_alignStart="@+id/button"
android:layout_alignParentTop="true"
android:layout_marginStart="96dp"
android:layout_marginTop="378dp" />
<Button
android:id="@+id/btnDateTime"
android:layout_width="180dp"
android:layout_height="wrap_content"
android:layout_below="@+id/textView13"
android:layout_alignParentStart="true"
android:layout_marginStart="-4dp"
android:text="Choose Date/Time" />
</RelativeLayout>
您需要从正在加载的XML中找到按钮
View v = inflater.inflate(R.layout.modal_event,container,false);
Button btnDateTime = (Button) findViewById(...);
btnDateTime.setOnClick...
return v;
如果你的应用程序崩溃了,会在某个地方打印堆栈跟踪(如果你正在使用Android Studio中的Logcat选项卡)。请找出这一点,并将其包括在问题中;这对诊断有很大帮助!好的,谢谢您,先生/妈妈错误消息告诉您要查看哪一行(Profile.java第55行)
btnDateTime
为空,因为它不在activity\u profile
中,因此findViewById
返回null如果在activity\u profile.xml
中没有按钮,则您试图在该类中查找的按钮将为空,并且可能重复
package com.example.khalessi_jb.reminderapplication;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.design.widget.BottomSheetDialogFragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class ModalEvent extends BottomSheetDialogFragment {
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.modal_event,container,false);
return v;
}
}
<?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:gravity="center_horizontal"
android:orientation="vertical"
android:padding="16dp">
<TextView
android:id="@+id/textView12"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Event" />
<EditText
android:id="@+id/txtEventName"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/textView12"
android:layout_centerHorizontal="true"
android:ems="10"
android:hint="Event Title"
android:inputType="textLongMessage" />
<EditText
android:id="@+id/txtWhere"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/textView15"
android:layout_alignStart="@+id/textView13"
android:ems="10"
android:hint="Event Location"
android:inputType="textLongMessage" />
<TextView
android:id="@+id/textView13"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/txtEventName"
android:layout_alignStart="@+id/txtEventName"
android:layout_marginTop="-1dp"
android:text="When" />
<EditText
android:id="@+id/txtDateTime"
android:layout_width="148dp"
android:layout_height="wrap_content"
android:layout_below="@+id/textView13"
android:layout_alignStart="@+id/textView12"
android:layout_marginStart="205dp"
android:layout_marginTop="0dp"
android:ems="10"
android:hint="Date/Time"
android:inputType="time"
android:textSize="15dp" />
<TextView
android:id="@+id/textView15"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/textView10"
android:layout_alignStart="@+id/textView13"
android:layout_marginStart="4dp"
android:text="Where" />
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignTop="@+id/textView12"
android:layout_alignParentEnd="true"
android:layout_marginTop="216dp"
android:layout_marginEnd="132dp"
android:text="Create" />
<Button
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignTop="@+id/button"
android:layout_alignParentEnd="true"
android:layout_marginTop="-1dp"
android:layout_marginEnd="15dp"
android:text="Close" />
<TextView
android:id="@+id/textView10"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/txtDateTime"
android:layout_alignParentStart="true"
android:layout_marginStart="0dp"
android:layout_marginEnd="21dp"
android:layout_toStartOf="@+id/txtDateTime"
android:text="at" />
<TextView
android:id="@+id/textView14"
android:layout_width="124dp"
android:layout_height="wrap_content"
android:layout_alignStart="@+id/button"
android:layout_alignParentTop="true"
android:layout_marginStart="96dp"
android:layout_marginTop="378dp" />
<Button
android:id="@+id/btnDateTime"
android:layout_width="180dp"
android:layout_height="wrap_content"
android:layout_below="@+id/textView13"
android:layout_alignParentStart="true"
android:layout_marginStart="-4dp"
android:text="Choose Date/Time" />
</RelativeLayout>
2018-11-06 20:32:19.439 20721-
20721/com.example.khalessi_jb.reminderapplication E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.khalessi_jb.reminderapplication, PID: 20721
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.khalessi_jb.reminderapplication/com.example.khalessi_jb.reminderapplication.Profile}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2724)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2789)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1527)
at android.os.Handler.dispatchMessage(Handler.java:110)
at android.os.Looper.loop(Looper.java:203)
at android.app.ActivityThread.main(ActivityThread.java:6259)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1063)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:924)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at com.example.khalessi_jb.reminderapplication.Profile.onCreate(Profile.java:55)
at android.app.Activity.performCreate(Activity.java:6666)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2677)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2789)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1527)
at android.os.Handler.dispatchMessage(Handler.java:110)
at android.os.Looper.loop(Looper.java:203)
at android.app.ActivityThread.main(ActivityThread.java:6259)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1063)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:924)
View v = inflater.inflate(R.layout.modal_event,container,false);
Button btnDateTime = (Button) findViewById(...);
btnDateTime.setOnClick...
return v;