如何解决如何访问不是活动的Java类中的xml文件的元素？
我有一个java类（不是活动）。通过它，我想访问xml文件（不是任何活动的布局文件）中的ImageView。 ImageView的ID为image_view。我的应用程序中有很多XML文件，其ID为image_view的ImageViews。如何从java类访问该特定xml文件中的ImageView？
这是我的代码：
package com.example.treeapp;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.util.Log;
import android.widget.ImageView;
import androidx.constraintlayout.widget.ConstraintLayout;
import java.io.IOException;
import java.net.URL;
public class DownloadImageTask extends AsyncTask<String,Void,Bitmap> {
private ImageView imageView; // I want to set this ImageView
@Override
protected Bitmap doInBackground(String... strings) {
try {
URL url = new URL(strings[0]);
return BitmapFactory.decodeStream(url.openStream());
}
catch (IOException e) {
Log.e("cs50","Download image error",e);
return null;
}
}
@Override
protected void onPostExecute(Bitmap bitmap) {
super.onPostExecute(bitmap);
imageView.setimageBitmap(bitmap);
}
}
这是我的xml文件
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:background="#ffbb00">
<androidx.constraintlayout.widget.Guideline
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/left_guideline_view"
app:layout_constraintGuide_percent=".12077"
android:orientation="vertical"/>
<androidx.constraintlayout.widget.Guideline
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/right_guideline_view"
app:layout_constraintGuide_percent=".87923"
android:orientation="vertical"/>
<androidx.constraintlayout.widget.Guideline
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/left_guideline_image_view"
app:layout_constraintGuide_percent=".16908"
android:orientation="vertical"/>
<androidx.constraintlayout.widget.Guideline
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/right_guideline_image_view"
app:layout_constraintGuide_percent=".32367"
android:orientation="vertical"/>
<androidx.constraintlayout.widget.Guideline
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/top_guideline_image_view"
app:layout_constraintGuide_percent=".14706"
android:orientation="horizontal"/>
<androidx.constraintlayout.widget.Guideline
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/bottom_guideline_image_view"
app:layout_constraintGuide_percent=".61765"
android:orientation="horizontal"/>
<androidx.constraintlayout.widget.Guideline
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/left_guideline_text_view"
app:layout_constraintGuide_percent=".37198"
android:orientation="vertical"/>
<androidx.constraintlayout.widget.Guideline
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/right_guideline_text_view"
app:layout_constraintGuide_percent=".72222"
android:orientation="vertical"/>
<androidx.constraintlayout.widget.Guideline
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/top_guideline_text_view_order"
app:layout_constraintGuide_percent=".13235"
android:orientation="horizontal"/>
<androidx.constraintlayout.widget.Guideline
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/bottom_guideline_text_view_order"
app:layout_constraintGuide_percent=".38235"
android:orientation="horizontal"/>
<androidx.constraintlayout.widget.Guideline
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/bottom_guideline_text_view_donor"
app:layout_constraintGuide_percent=".61765"
android:orientation="horizontal"/>
<androidx.constraintlayout.widget.Guideline
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/left_guideline_send_image_icon"
app:layout_constraintGuide_percent=".32367"
android:orientation="vertical"/>
<androidx.constraintlayout.widget.Guideline
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/right_guideline_send_image_icon"
app:layout_constraintGuide_percent=".43961"
android:orientation="vertical"/>
<androidx.constraintlayout.widget.Guideline
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/top_guideline_icon"
app:layout_constraintGuide_percent=".74265"
android:orientation="horizontal"/>
<androidx.constraintlayout.widget.Guideline
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/bottom_guideline_icon"
app:layout_constraintGuide_percent=".96324"
android:orientation="horizontal"/>
<androidx.constraintlayout.widget.Guideline
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/left_guideline_message_icon"
app:layout_constraintGuide_percent=".58696"
android:orientation="vertical"/>
<androidx.constraintlayout.widget.Guideline
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/right_guideline_message_icon"
app:layout_constraintGuide_percent=".70290"
android:orientation="vertical"/>
<FrameLayout
android:layout_width="0dp"
android:layout_height="0dp"
android:id="@+id/left_border"
android:background="#ffbb00"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="@id/left_guideline_view"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent">
<Button
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#ffbb00" />
</FrameLayout>
<FrameLayout
android:layout_width="0dp"
android:layout_height="0dp"
android:id="@+id/right_border"
android:background="#ffbb00"
app:layout_constraintLeft_toLeftOf="@id/right_guideline_view"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent">
<Button
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#ffbb00" />
</FrameLayout>
<FrameLayout
android:layout_width="0dp"
android:layout_height="0dp"
android:id="@+id/middle"
android:paddingTop="8dp"
android:paddingBottom="8dp"
app:layout_constraintLeft_toLeftOf="@+id/left_guideline_view"
app:layout_constraintRight_toRightOf="@id/right_guideline_view"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent">
<Button
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/order_planter_message_shape" />
</FrameLayout>
<ImageView
android:layout_width="0dp"
android:layout_height="0dp"
android:id="@+id/image_view"
android:background="@drawable/profile_picture_shape"
app:layout_constraintLeft_toLeftOf="@+id/left_guideline_image_view"
app:layout_constraintRight_toRightOf="@+id/right_guideline_image_view"
app:layout_constraintTop_toTopOf="@+id/top_guideline_image_view"
app:layout_constraintBottom_toBottomOf="@+id/bottom_guideline_image_view"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/text_view_order"
android:text="Plant # Trees"
android:fontFamily="@font/inter_semibold"
android:textSize="24sp"
android:textColor="#6633ff"
android:textAlignment="center"
android:textAllCaps="false"
app:layout_constraintLeft_toLeftOf="@+id/left_guideline_text_view"
app:layout_constraintRight_toRightOf="@+id/right_guideline_text_view"
app:layout_constraintTop_toTopOf="@+id/top_guideline_text_view_order"
app:layout_constraintBottom_toBottomOf="@+id/bottom_guideline_text_view_order"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/text_view_donor"
android:text="David Malan,$20"
android:fontFamily="@font/inter_regular"
android:textSize="18sp"
android:textColor="#6633ff"
android:textAlignment="center"
android:textAllCaps="false"
app:layout_constraintLeft_toLeftOf="@+id/left_guideline_text_view"
app:layout_constraintRight_toRightOf="@+id/right_guideline_text_view"
app:layout_constraintTop_toTopOf="@+id/bottom_guideline_text_view_order"
app:layout_constraintBottom_toBottomOf="@+id/bottom_guideline_text_view_donor"/>
<com.airbnb.lottie.LottieAnimationView
android:layout_width="0dp"
android:layout_height="0dp"
android:id="@+id/send_image_icon"
app:lottie_fileName="28699-photo-icon.json"
app:lottie_autoplay="true"
app:lottie_loop="true"
app:layout_constraintLeft_toLeftOf="@+id/left_guideline_send_image_icon"
app:layout_constraintRight_toRightOf="@+id/right_guideline_send_image_icon"
app:layout_constraintTop_toTopOf="@+id/top_guideline_icon"
app:layout_constraintBottom_toBottomOf="@+id/bottom_guideline_icon"/>
<com.airbnb.lottie.LottieAnimationView
android:layout_width="0dp"
android:layout_height="0dp"
android:id="@+id/message_icon"
app:lottie_fileName="28699-photo-icon.json"
app:lottie_autoplay="true"
app:lottie_loop="true"
app:layout_constraintLeft_toLeftOf="@+id/left_guideline_message_icon"
app:layout_constraintRight_toRightOf="@+id/right_guideline_message_icon"
app:layout_constraintTop_toTopOf="@+id/top_guideline_icon"
app:layout_constraintBottom_toBottomOf="@+id/bottom_guideline_icon"/>
</androidx.constraintlayout.widget.ConstraintLayout>
解决方法
可能我错了，但我的建议是：
public class DownloadImageTask extends AsyncTask<String,Void,Bitmap> {
private ImageView imageView; // I want to set this ImageView
public DownloadImageTask(Context context){
View view = View.inflate(context,R.layout.your_layout,null);
imageView = view.findViewById<ImageView>(R.id.image_view);
}
@Override
protected Bitmap doInBackground(String... strings) {
try {
URL url = new URL(strings[0]);
return BitmapFactory.decodeStream(url.openStream());
}
catch (IOException e) {
Log.e("cs50","Download image error",e);
return null;
}
}
@Override
protected void onPostExecute(Bitmap bitmap) {
super.onPostExecute(bitmap);
imageView.setImageBitmap(bitmap);
}
}
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