将RecyclerView中的数据应用到MainActivity。

huangapple
go评论98阅读模式
英文:

How to apply data from RecyclerView to MainActivity

问题

以下是您的翻译内容：

我有一个带有图片的水平Recyclerview。我想要当我点击Recyclerview上的图片时，设置我的MainActivity imageView 的背景。我不知道如何从Recyclerview应用到我的Mainactivity类。

这是我的MainActivity类：

  1. class MainActivity : AppCompatActivity() {
  3.     private lateinit var recyclerView: RecyclerView
  4.     private var imagesUrl: ArrayList<String> = ArrayList()
  6.     override fun onCreate(savedInstanceState: Bundle?) {
  7.         super.onCreate(savedInstanceState)
  8.         setContentView(R.layout.activity_main)
  10.         takeCapture.setOnClickListener(takePictureListener)
  12.         getImagesUrl()
  13.     }
  15.     private fun getImagesUrl() {
  16.         imagesUrl.apply {
  17.             add("https://image.freepik.com/free-photo/dark-studio-background_1258-14.jpg")
  18.             add("https://i.pinimg.com/236x/e7/f6/47/e7f647952cc3f7381d0707965e422db0.jpg")
  19.             add("https://image.freepik.com/free-vector/abstract-dark-black-background-studio-room-with-sportlight_1035-18643.jpg")
  20.             add("https://thumbs.dreamstime.com/z/empty-black-studio-room-dark-background-abstract-texture-product-showcase-spotlight-gallery-136762537.jpg")
  21.         }
  22.         initRecyclerView()
  23.     }
  25.     private fun initRecyclerView() {
  26.         recyclerView = findViewById(R.id.recyclerView)
  27.         recyclerView.apply {
  28.             layoutManager = LinearLayoutManager(applicationContext, LinearLayoutManager.HORIZONTAL, false)
  29.             adapter = ImageAdapter(applicationContext, imagesUrl)
  30.         }
  31.     }
  33.     private val takePictureListener = View.OnClickListener {
  34.         val intent = Intent(MediaStore.ACTION_IMAGE_CAPTURE)
  35.         startActivityForResult(intent, 0)
  36.     }
  38.     override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
  39.         super.onActivityResult(requestCode, resultCode, data)
  41.         val bitmap = data!!.extras!!.get("data") as Bitmap
  42.         val resized = Bitmap.createScaledBitmap(bitmap, 700, 550, true)
  43.         imageView.setImageBitmap(resized)
  44.     }
  45. }

以及我的RecyclerView Adapter类：

  1. class ImageAdapter(private val context: Context, private val list: ArrayList<String>) : RecyclerView.Adapter<ImageAdapter.ViewHolder>() {
  3.     override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
  4.         val view = LayoutInflater.from(parent.context).inflate(R.layout.image_recycler, parent, false)
  5.         return ViewHolder(view)
  6.     }
  8.     override fun onBindViewHolder(holder: ViewHolder, position: Int) {
  9.         Picasso.get().load(list[position]).into(holder.circleImageView)
  10.     }
  12.     override fun getItemCount(): Int = list.size
  14.     inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
  15.         val circleImageView : CircleImageView = itemView.circleImage
  16.     }
  17. }
英文:

I have horizontal Recyclerview with images. I want when I click the image on Recyclerview to set the background of my MainActivity imageView. I don't know how to apply from Recyclerview to my Mainactivity class.

This is my MainActivity class:

  1.  class MainActivity : AppCompatActivity() {
  2.     
  3.         private lateinit var recyclerView: RecyclerView
  4.         private var imagesUrl: ArrayList&lt;String&gt; = ArrayList()
  5.         
  6.         override fun onCreate(savedInstanceState: Bundle?) {
  7.             super.onCreate(savedInstanceState)
  8.             setContentView(R.layout.activity_main)
  9.     
  10.             takeCapture.setOnClickListener(takePictureListener)
  11.     
  12.             getImagesUrl()
  13.         }
  14.     
  15.         private fun getImagesUrl() {
  16.             imagesUrl.apply {
  17.                 add(&quot;https://image.freepik.com/free-photo/dark-studio-background_1258-14.jpg&quot;)
  18.                 add(&quot;https://i.pinimg.com/236x/e7/f6/47/e7f647952cc3f7381d0707965e422db0.jpg&quot;)
  19.                 add(&quot;https://image.freepik.com/free-vector/abstract-dark-black-background-studio-room-with-sportlight_1035-18643.jpg&quot;)
  20.                 add(&quot;https://thumbs.dreamstime.com/z/empty-black-studio-room-dark-background-abstract-texture-product-showcase-spotlight-gallery-136762537.jpg&quot;)
  21.             }
  22.             initRecyclerView()
  23.         }
  24.     
  25.         private fun initRecyclerView() {
  26.             recyclerView = findViewById(R.id.recyclerView)
  27.             recyclerView.apply {
  28.                 layoutManager = LinearLayoutManager(applicationContext, LinearLayoutManager.HORIZONTAL, false)
  29.                 adapter = ImageAdapter(applicationContext, imagesUrl)
  30.             }
  31.         }
  32.     
  33.         private val takePictureListener = View.OnClickListener {
  34.             val intent = Intent(MediaStore.ACTION_IMAGE_CAPTURE)
  35.             startActivityForResult(intent, 0)
  36.         }
  37.     
  38.         override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
  39.             super.onActivityResult(requestCode, resultCode, data)
  40.     
  41.             val bitmap = data!!.extras!!.get(&quot;data&quot;) as Bitmap
  42.             val resized = Bitmap.createScaledBitmap(bitmap, 700, 550, true)
  43.             imageView.setImageBitmap(resized)
  44.         }
  46. }

And my RecyclerView Adapter class

  1. class ImageAdapter(private val context: Context, private val list: ArrayList&lt;String&gt;) : RecyclerView.Adapter&lt;ImageAdapter.ViewHolder&gt;() {
  3.     override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
  4.         val view = LayoutInflater.from(parent.context).inflate(R.layout.image_recycler, parent, false)
  5.         return ViewHolder(view)
  6.     }
  8.     override fun onBindViewHolder(holder: ViewHolder, position: Int) {
  9.         Picasso.get().load(list[position]).into(holder.circleImageView)
  10.     }
  12.     override fun getItemCount(): Int = list.size
  14.     inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
  15.         val circleImageView : CircleImageView = itemView.circleImage
  16.     }
  17. }

答案1

得分: 3

以下是您要翻译的代码部分：

  1. 这里我使用了回调方法与接口，当您的RecyclerView中的任何项目被点击时，您将获得一个回调，您可以在活动中使用该回调进行相应的修改。
  3. 您的MainActivity类将变成这样：-
  5. class MainActivity : AppCompatActivity(): ImagesAdapter.OnItemClickListener {
  7.     private lateinit var recyclerView: RecyclerView
  8.     private var imagesUrl: ArrayList<String> = ArrayList()
  9.     private lateinit var imageAdapter: ImageAdapter
  11.     override fun onCreate(savedInstanceState: Bundle?) {
  12.         super.onCreate(savedInstanceState)
  13.         setContentView(R.layout.activity_main)
  15.         takeCapture.setOnClickListener(takePictureListener)
  17.         getImagesUrl()
  18.     }
  20.     private fun getImagesUrl() {
  21.         imagesUrl.apply {
  22.             add("https://image.freepik.com/free-photo/dark-studio-background_1258-14.jpg")
  23.             add("https://i.pinimg.com/236x/e7/f6/47/e7f647952cc3f7381d0707965e422db0.jpg")
  24.             add("https://image.freepik.com/free-vector/abstract-dark-black-background-studio-room-with-sportlight_1035-18643.jpg")
  25.             add("https://thumbs.dreamstime.com/z/empty-black-studio-room-dark-background-abstract-texture-product-showcase-spotlight-gallery-136762537.jpg")
  26.         }
  27.         initRecyclerView()
  28.     }
  30.     private fun initRecyclerView() {
  31.         recyclerView = findViewById(R.id.recyclerView)
  32.         recyclerView.layoutManager = LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false) //您的活动的上下文
  33.         imageAdapter = ImageAdapter(this, imagesUrl) //您的活动的上下文
  34.         recyclerView.adapter = imageAdapter
  35.         imageAdapter.setOnItemClickListener(this)
  36.     }
  38.     private val takePictureListener = View.OnClickListener {
  39.         val intent = Intent(MediaStore.ACTION_IMAGE_CAPTURE)
  40.         startActivityForResult(intent, 0)
  41.     }
  43.     override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
  44.         super.onActivityResult(requestCode, resultCode, data)
  46.         val bitmap = data!!.extras!!.get("data") as Bitmap
  47.         val resized = Bitmap.createScaledBitmap(bitmap, 700, 550, true)
  48.         imageView.setImageBitmap(resized)
  49.     }
  51.     override fun onItemClicked(backroundImage: String) {
  52.         Picasso.get().load(backroundImage).into(imageView) //在这里传递您的活动类的ImageView
  53.     }
  55. }
  57. 而您的适配器类更改将如下所示：-
  59. class ImageAdapter(private val context: Context, private val list: ArrayList<String>) : RecyclerView.Adapter<ImageAdapter.ViewHolder>() {
  61.     private lateinit var onItemClickListener: OnItemClickListener
  63.     override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
  64.         val view = LayoutInflater.from(parent.context).inflate(R.layout.image_recycler, parent, false)
  65.         return ViewHolder(view)
  66.     }
  68.     override fun onBindViewHolder(holder: ViewHolder, position: Int) {
  69.         Picasso.get().load(list[position]).into(holder.circleImageView)
  70.     }
  72.     override fun getItemCount(): Int = list.size
  74.     inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
  75.         val circleImageView: CircleImageView = itemView.circleImage
  76.         itemView.setOnItemClickListener {
  77.             if (::onItemClickListener.isInitialized)
  78.                 onItemClickListener.onItemClicked(list[adapterPosition])
  79.         }
  80.     }
  82.     interface OnItemClickListener {
  83.         fun onItemClicked(background: String)
  84.     }
  86.     fun setOnItemClickListener(onItemClickListener: OnItemClickListener) {
  87.         this.onItemClickListener = onItemClickListener
  88.     }
  89. }

希望这对您有所帮助！如果您有任何其他翻译请求，请随时提出。

英文:

Here I have used callback approach with interfaces where on the click of any item in your recyclerView you'll be getting a callback and you can do alteration accordingly with that callback in your activity.

Your MainActivity class will become something like this:-

  1. class MainActivity : AppCompatActivity():ImagesAdapter.OnItemClickListener {
  2. private lateinit var recyclerView: RecyclerView
  3. private var imagesUrl: ArrayList&lt;String&gt; = ArrayList()
  4. private lateinit var imageAdapter:ImageAdapter
  5. override fun onCreate(savedInstanceState: Bundle?) {
  6. super.onCreate(savedInstanceState)
  7. setContentView(R.layout.activity_main)
  8. takeCapture.setOnClickListener(takePictureListener)
  9. getImagesUrl()
  10. }
  11. private fun getImagesUrl() {
  12. imagesUrl.apply {
  13. add(&quot;https://image.freepik.com/free-photo/dark-studio-background_1258-14.jpg&quot;)
  14. add(&quot;https://i.pinimg.com/236x/e7/f6/47/e7f647952cc3f7381d0707965e422db0.jpg&quot;)
  15. add(&quot;https://image.freepik.com/free-vector/abstract-dark-black-background-studio-room-with-sportlight_1035-18643.jpg&quot;)
  16. add(&quot;https://thumbs.dreamstime.com/z/empty-black-studio-room-dark-background-abstract-texture-product-showcase-spotlight-gallery-136762537.jpg&quot;)
  17. }
  18. initRecyclerView()
  19. }
  20. private fun initRecyclerView() {
  21. recyclerView = findViewById(R.id.recyclerView)
  22. recyclerView.layoutManager = LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false)        //Your activity&#39;s context
  23. imageAdapter = ImageAdapter(this, imagesUrl)        //Your activity&#39;s context
  24. recyclerView.adapter = imageAdapter
  25. imageAdapter.setOnItemClickListener(this)
  26. }
  27. private val takePictureListener = View.OnClickListener {
  28. val intent = Intent(MediaStore.ACTION_IMAGE_CAPTURE)
  29. startActivityForResult(intent, 0)
  30. }
  31. override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
  32. super.onActivityResult(requestCode, resultCode, data)
  33. val bitmap = data!!.extras!!.get(&quot;data&quot;) as Bitmap
  34. val resized = Bitmap.createScaledBitmap(bitmap, 700, 550, true)
  35. imageView.setImageBitmap(resized)
  36. }
  37. override fun onItemClicked(backroundImage:String){
  38. Picasso.get().load(backroundImage).into(imageView)         //Here pass the image view of your activity class
  39. }
  40. }

And your adapter class changes will be something like this:-

  1. class ImageAdapter(private val context: Context, private val list: ArrayList&lt;String&gt;) : RecyclerView.Adapter&lt;ImageAdapter.ViewHolder&gt;() {
  2. private lateinit var onItemClickListener:OnItemClickListener
  3. override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
  4. val view = LayoutInflater.from(parent.context).inflate(R.layout.image_recycler, parent, false)
  5. return ViewHolder(view)
  6. }
  7. override fun onBindViewHolder(holder: ViewHolder, position: Int) {
  8. Picasso.get().load(list[position]).into(holder.circleImageView)
  9. }
  10. override fun getItemCount(): Int = list.size
  11. inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
  12. val circleImageView : CircleImageView = itemView.circleImage
  13. itemView.setOnItemClickListener{
  14. if (::onItemClickListener.isInitialized)
  15. onItemClickListener.onItemClicked(list[adapterPosition])
  16. }
  17. }
  18. interface OnItemClickListener{
  19. fun onItemClicked(background:String)
  20. }
  21. fun setOnItemClickListener(onItemClickListener:OnItemClickListener){
  22. this.onItemClickListener = onItemClickListener
  23. }
  24. }

答案2

得分: 0

最简单的解决方案是将对MainActivity的引用传递给ImageAdapter：

  1. // 将ImageAdapter的构造函数更改为
  2. class ImageAdapter(
  3.   private val context: Context, 
  4.   private val list: ArrayList<String>,
  5.   private val activity: MainActivity
  6. )

在MainActivity中添加一个公共方法来更改背景：

  1. fun changeBackground(drawable: Drawable) {
  2.   // 更改MainActivity的背景
  3. }

然后在ImageAdapter内调用该方法：

  1. override fun onBindViewHolder(holder: ViewHolder, position: Int) {
  2.   ...
  3.   activity.changeBackground()
  4. }

您还可以考虑将ImageAdapter与MainActivity解耦，并将回调函数（例如(Drawable) -> Unit）传递给ImageAdapter。在这种情况下，MainActivity将向ImageAdapter的构造函数传递一个lambda表达式，ImageAdapter将在onClickListener内部调用该lambda表达式。

英文:

The simplest solution would be to pass a reference to MainActivity into the ImageAdapter:

  1. // Change ImageAdapter&#39;s constructor to
  2. class ImageAdapter(
  3. private val context: Context, 
  4. private val list: ArrayList&lt;String&gt;,
  5. private val activity: MainActivity
  6. )
  7. // In MainActivity
  8. adapter = ImageAdapter(applicationContext, imagesUrl, this)

Add a public method to MainActivity that changes the background:

  1. fun changeBackground(drawable: Drawable) {
  2. // Change MainActivity&#39;s background
  3. }

And call that method inside ImageAdapter:

  1. override fun onBindViewHolder(holder: ViewHolder, position: Int) {
  2. ...
  3. activity.changeBackground()
  4. }

You might also want to decouple ImageAdapter from MainActivity and pass a callback function, e.g. (Drawable) -&gt; Unit, into ImageAdapter instead. In this case, MainActivity will pass a lambda to ImageAdapter's constructor, and ImageAdapter will call that lambda inside an onClickListener.

huangapple
  • 本文由 发表于 2020年8月3日 21:05:58
  • 转载请务必保留本文链接：https://go.coder-hub.com/63230015.html
  • android
  • java
  • kotlin
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