Java 为什么试图在包含的布局中的元素上设置onClickListener会引发NullPointerException?
我试图使用Java 为什么试图在包含的布局中的元素上设置onClickListener会引发NullPointerException?,java,android,android-studio,kotlin,Java,Android,Android Studio,Kotlin,我试图使用将布局链接到我的主方法,但我一直失败。我已经花了一天半的时间通过阅读这些问题来解决这个问题,但我一直在重复同样的问题。我想知道我做错了什么,这样我就可以避免这段时间在未来的沉沦,但是其他地方提出的可能的解决方案都不起作用 项目菜单布局.xml <?xml version="1.0" encoding="utf-8"?> <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://sc
将布局链接到我的主方法,但我一直失败。我已经花了一天半的时间通过阅读这些问题来解决这个问题,但我一直在重复同样的问题。我想知道我做错了什么,这样我就可以避免这段时间在未来的沉沦,但是其他地方提出的可能的解决方案都不起作用
项目菜单布局.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/ItemMenu"
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.constraintlayout.widget.ConstraintLayout
android:id="@+id/ItemMenuLayout"
android:layout_width="350dp"
android:layout_height="400dp"
android:background="#FFFFFF"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<TextView
android:id="@+id/itemMenuTitle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:text="@string/item_menu_label"
android:textSize="24sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/itemMenuDescription"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:padding="10dp"
android:text="@string/lorem_ipsum"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/itemMenuTitle" />
<LinearLayout
android:id="@+id/SelectActionLayout"
android:layout_width="320dp"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintBottom_toTopOf="@+id/deleteOrSetLayout"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent">
<Button
android:id="@+id/addItemButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="@string/add_label"
android:textAllCaps="false" />
<Button
android:id="@+id/modifyItemButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="@string/modify_label"
android:textAllCaps="false" />
</LinearLayout>
<LinearLayout
android:id="@+id/deleteOrSetLayout"
android:layout_width="320dp"
android:layout_height="wrap_content"
android:layout_marginBottom="60dp"
android:orientation="horizontal"
app:layout_constraintBottom_toTopOf="@+id/button5"
app:layout_constraintEnd_toEndOf="@+id/SelectActionLayout"
app:layout_constraintStart_toStartOf="@+id/SelectActionLayout">
<Button
android:id="@+id/deleteItemButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="@string/delete_label"
android:textAllCaps="false" />
<Button
android:id="@+id/setItemsButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="@string/set_active_label"
android:textAllCaps="false" />
</LinearLayout>
<Button
android:id="@+id/button5"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/return_to_grid_label"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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:id="@+id/AddItemLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#FFFFFF">
<TextView
android:id="@+id/addItemTitle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:text="@string/add_item_title"
android:textSize="26sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/addItemDescription"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:padding="15dp"
android:text="@string/lorem_ipsum"
android:textAlignment="center"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/addItemTitle" />
<Button
android:id="@+id/submitItemButton"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Add Item"
android:textAllCaps="false"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
<LinearLayout
android:id="@+id/NameLayout"
android:layout_width="300dp"
android:layout_height="50dp"
android:layout_marginTop="16dp"
android:orientation="horizontal"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/addItemDescription">
<TextView
android:id="@+id/nameTag"
android:layout_width="23dp"
android:layout_height="38dp"
android:layout_weight="1"
android:padding="5dp"
android:text="@string/name_label"
android:textAlignment="center"
android:textSize="20sp" />
<EditText
android:id="@+id/nameInput"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:ems="10"
android:inputType="textPersonName" />
</LinearLayout>
<LinearLayout
android:id="@+id/DescriptionLayout"
android:layout_width="300dp"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:layout_weight="1"
android:orientation="horizontal"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/NameLayout">
<TextView
android:id="@+id/descriptionTag"
android:layout_width="23dp"
android:layout_height="38dp"
android:layout_weight="1"
android:padding="5dp"
android:text="@string/description_title"
android:textAlignment="center"
android:textSize="20sp" />
<EditText
android:id="@+id/descriptionInput"
android:layout_width="70dp"
android:layout_height="100dp"
android:layout_weight="1"
android:ems="10"
android:gravity="center"
android:inputType="textMultiLine" />
</LinearLayout>
<LinearLayout
android:id="@+id/LabelLayout"
android:layout_width="300dp"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:orientation="horizontal"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/DescriptionLayout">
<TextView
android:id="@+id/labelTag"
android:layout_width="23dp"
android:layout_height="38dp"
android:layout_weight="1"
android:text="Label"
android:textAlignment="center"
android:textSize="20sp" />
<EditText
android:id="@+id/labelInput"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:ems="10"
android:inputType="textPersonName" />
</LinearLayout>
<LinearLayout
android:id="@+id/ImageLayout"
android:layout_width="300dp"
android:layout_height="wrap_content"
android:layout_marginTop="26dp"
android:gravity="center"
android:orientation="horizontal"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/LabelLayout">
<TextView
android:id="@+id/imageTag"
android:layout_width="23dp"
android:layout_height="38dp"
android:layout_weight="1"
android:gravity="bottom|center_horizontal"
android:text="Image"
android:textSize="20sp" />
<Button
android:id="@+id/addImageButton"
android:layout_width="175dp"
android:layout_height="wrap_content"
android:layout_marginTop="5dp"
android:gravity="center|center_vertical"
android:text="Add Image ..."
android:textAllCaps="false" />
</LinearLayout>
<ImageView
android:id="@+id/uploadedImagePreview"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintBottom_toTopOf="@+id/submitItemButton"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/ImageLayout"
tools:srcCompat="@tools:sample/avatars" />
</androidx.constraintlayout.widget.ConstraintLayout>
<?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:id="@+id/ItemGridLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#fff"
tools:context=".MainActivity">
<include
android:id="@+id/addItemLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
layout="@layout/add_item_layout" />
<include
android:id="@+id/itemMenuLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
layout="@layout/item_menu_layout"/>
<!-- <include layout="@layout/header" android:id="@+id/header"/> -->
<GridView
android:id="@+id/gridView"
android:layout_width="match_parent"
android:layout_height="500dp"
android:layout_above="@+id/ButtonLayout"
android:divider="#000000"
android:dividerHeight="1dp"
android:gravity="center_vertical"
android:horizontalSpacing="10dp"
android:listSelector="@drawable/list_selector"
android:numColumns="2"
android:padding="5dp"
android:stretchMode="columnWidth"
android:verticalSpacing="10dp">
</GridView>
<TextView
android:id="@+id/projectTitleView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_alignParentEnd="true"
android:layout_marginStart="174dp"
android:layout_marginTop="22dp"
android:layout_marginEnd="179dp"
android:text="TextView" />
<LinearLayout
android:id="@+id/ButtonLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:background="#000000">
<Button
android:id="@+id/incrementButton"
android:layout_width="wrap_content"
android:layout_height="70dp"
android:layout_weight=".8"
android:backgroundTint="#000000"
android:text="@string/increment_button_plus"
android:textColor="#FFFFFF"
android:textSize="40dp" />
<Button
android:id="@+id/decrementButton"
android:layout_width="wrap_content"
android:layout_height="70dp"
android:layout_weight=".8"
android:backgroundTint="#000000"
android:text="@string/decrement_button_minus"
android:textColor="#FFFFFF"
android:textSize="40dp" />
</LinearLayout>
</RelativeLayout>
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.mts.itemcounter">
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".ChooseProjectActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".MainActivity"/>
</application>
</manifest>
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/ItemMenu"
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.constraintlayout.widget.ConstraintLayout
android:id="@+id/ItemMenuLayout"
android:layout_width="350dp"
android:layout_height="400dp"
android:background="#FFFFFF"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<TextView
android:id="@+id/itemMenuTitle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:text="@string/item_menu_label"
android:textSize="24sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/itemMenuDescription"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:padding="10dp"
android:text="@string/lorem_ipsum"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/itemMenuTitle" />
<LinearLayout
android:id="@+id/SelectActionLayout"
android:layout_width="320dp"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintBottom_toTopOf="@+id/deleteOrSetLayout"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent">
<Button
android:id="@+id/addItemButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="@string/add_label"
android:textAllCaps="false" />
<Button
android:id="@+id/modifyItemButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="@string/modify_label"
android:textAllCaps="false" />
</LinearLayout>
<LinearLayout
android:id="@+id/deleteOrSetLayout"
android:layout_width="320dp"
android:layout_height="wrap_content"
android:layout_marginBottom="60dp"
android:orientation="horizontal"
app:layout_constraintBottom_toTopOf="@+id/button5"
app:layout_constraintEnd_toEndOf="@+id/SelectActionLayout"
app:layout_constraintStart_toStartOf="@+id/SelectActionLayout">
<Button
android:id="@+id/deleteItemButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="@string/delete_label"
android:textAllCaps="false" />
<Button
android:id="@+id/setItemsButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="@string/set_active_label"
android:textAllCaps="false" />
</LinearLayout>
<Button
android:id="@+id/button5"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/return_to_grid_label"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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:id="@+id/AddItemLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#FFFFFF">
<TextView
android:id="@+id/addItemTitle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:text="@string/add_item_title"
android:textSize="26sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/addItemDescription"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:padding="15dp"
android:text="@string/lorem_ipsum"
android:textAlignment="center"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/addItemTitle" />
<Button
android:id="@+id/submitItemButton"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Add Item"
android:textAllCaps="false"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
<LinearLayout
android:id="@+id/NameLayout"
android:layout_width="300dp"
android:layout_height="50dp"
android:layout_marginTop="16dp"
android:orientation="horizontal"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/addItemDescription">
<TextView
android:id="@+id/nameTag"
android:layout_width="23dp"
android:layout_height="38dp"
android:layout_weight="1"
android:padding="5dp"
android:text="@string/name_label"
android:textAlignment="center"
android:textSize="20sp" />
<EditText
android:id="@+id/nameInput"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:ems="10"
android:inputType="textPersonName" />
</LinearLayout>
<LinearLayout
android:id="@+id/DescriptionLayout"
android:layout_width="300dp"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:layout_weight="1"
android:orientation="horizontal"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/NameLayout">
<TextView
android:id="@+id/descriptionTag"
android:layout_width="23dp"
android:layout_height="38dp"
android:layout_weight="1"
android:padding="5dp"
android:text="@string/description_title"
android:textAlignment="center"
android:textSize="20sp" />
<EditText
android:id="@+id/descriptionInput"
android:layout_width="70dp"
android:layout_height="100dp"
android:layout_weight="1"
android:ems="10"
android:gravity="center"
android:inputType="textMultiLine" />
</LinearLayout>
<LinearLayout
android:id="@+id/LabelLayout"
android:layout_width="300dp"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:orientation="horizontal"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/DescriptionLayout">
<TextView
android:id="@+id/labelTag"
android:layout_width="23dp"
android:layout_height="38dp"
android:layout_weight="1"
android:text="Label"
android:textAlignment="center"
android:textSize="20sp" />
<EditText
android:id="@+id/labelInput"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:ems="10"
android:inputType="textPersonName" />
</LinearLayout>
<LinearLayout
android:id="@+id/ImageLayout"
android:layout_width="300dp"
android:layout_height="wrap_content"
android:layout_marginTop="26dp"
android:gravity="center"
android:orientation="horizontal"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/LabelLayout">
<TextView
android:id="@+id/imageTag"
android:layout_width="23dp"
android:layout_height="38dp"
android:layout_weight="1"
android:gravity="bottom|center_horizontal"
android:text="Image"
android:textSize="20sp" />
<Button
android:id="@+id/addImageButton"
android:layout_width="175dp"
android:layout_height="wrap_content"
android:layout_marginTop="5dp"
android:gravity="center|center_vertical"
android:text="Add Image ..."
android:textAllCaps="false" />
</LinearLayout>
<ImageView
android:id="@+id/uploadedImagePreview"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintBottom_toTopOf="@+id/submitItemButton"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/ImageLayout"
tools:srcCompat="@tools:sample/avatars" />
</androidx.constraintlayout.widget.ConstraintLayout>
<?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:id="@+id/ItemGridLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#fff"
tools:context=".MainActivity">
<include
android:id="@+id/addItemLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
layout="@layout/add_item_layout" />
<include
android:id="@+id/itemMenuLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
layout="@layout/item_menu_layout"/>
<!-- <include layout="@layout/header" android:id="@+id/header"/> -->
<GridView
android:id="@+id/gridView"
android:layout_width="match_parent"
android:layout_height="500dp"
android:layout_above="@+id/ButtonLayout"
android:divider="#000000"
android:dividerHeight="1dp"
android:gravity="center_vertical"
android:horizontalSpacing="10dp"
android:listSelector="@drawable/list_selector"
android:numColumns="2"
android:padding="5dp"
android:stretchMode="columnWidth"
android:verticalSpacing="10dp">
</GridView>
<TextView
android:id="@+id/projectTitleView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_alignParentEnd="true"
android:layout_marginStart="174dp"
android:layout_marginTop="22dp"
android:layout_marginEnd="179dp"
android:text="TextView" />
<LinearLayout
android:id="@+id/ButtonLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:background="#000000">
<Button
android:id="@+id/incrementButton"
android:layout_width="wrap_content"
android:layout_height="70dp"
android:layout_weight=".8"
android:backgroundTint="#000000"
android:text="@string/increment_button_plus"
android:textColor="#FFFFFF"
android:textSize="40dp" />
<Button
android:id="@+id/decrementButton"
android:layout_width="wrap_content"
android:layout_height="70dp"
android:layout_weight=".8"
android:backgroundTint="#000000"
android:text="@string/decrement_button_minus"
android:textColor="#FFFFFF"
android:textSize="40dp" />
</LinearLayout>
</RelativeLayout>
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.mts.itemcounter">
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".ChooseProjectActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".MainActivity"/>
</application>
</manifest>
我知道这是很多,但我不知道我排除了什么、遗漏了什么或做错了什么
我知道我试图设置这些侦听器的按钮被读取为空,但我真的不知道如何使它们不那么空,我想?删除这些行
val addItemButton = menuLayout.findViewById<Button>(R.id.addItemButton)
val addItemButton=menuLayout.findViewById(R.id.addItemButton)
及
val submitItemButton=itemLayout.findViewById(R.id.submitItemButton)
更改此行
var menuLayout = findViewById<ConstraintLayout>(R.id.ItemMenu)
var menuLayout=findviewbyd(R.id.itemsmenu)
到
var menuLayout=findviewbyd(R.id.ItemMenuLayout)
希望这有助于哪一行出现错误?Hardik Parmar,我在所提供代码底部的
addItemButton.setOnClickListener{}
和submitItemButton.setOnClickListener{}
处发现错误。不必绑定include layout。是否可以添加此布局=“@layout/add\u item\u layout”我不知道为什么这样做有效,因为我最初添加这些是因为我遇到了类似的问题,但它有效。谢谢你指出我的遗忘:P我只希望有一天我能如此迅速地识别和指出人们的问题。