我在代码中遗漏了什么？是导入还是额外的代码行？答案

【问题标题】：What am I missing in the code? Is it the import or is it extra line of code?我在代码中遗漏了什么？是导入还是额外的代码行？
【发布时间】：2021-12-31 11:31:08
【问题描述】：

package com.example.myapplication2

import android.content.Intent
import android.net.Uri
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.os.Parcelable
import android.widget.TextView
import android.widget.ImageView

 class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

       when {
            intent?.action == Intent.ACTION_SEND -> {
               when {
                 intent.type == PLAIN_TEXT_MIME -> handleSendText(intent)
                 intent.type?.startsWith(MEDIA_IMAGE_MIME) == true -> 
         handleSendImage(intent) // Handle single image being sent
            }
        }
        intent?.action == Intent.ACTION_SEND_MULTIPLE -> {
            when {
                intent.type?.startsWith(MEDIA_IMAGE_MIME) == true -> handleSendMultipleImages(intent)
            }
        }
    }
}

private fun handleSendText(intent: Intent) {
    intent.getStringExtra(Intent.EXTRA_TEXT)?.let {
       val textView.text = it // Update UI to reflect text being shared
    }
}

private fun handleSendImage(intent: Intent) {
    (intent.getParcelableExtra<Parcelable>(Intent.EXTRA_STREAM) as? Uri)?.let {
       val first_ImageView.setImageURI(it)// Update UI to reflect image being shared
    }
}

private fun handleSendMultipleImages(intent: Intent) {
    intent.getParcelableArrayListExtra<Parcelable>(Intent.EXTRA_STREAM)?.let {
        first_imageView.setImageURI(it(0) as? Uri)
        second_imageView.setImageURI(it(1) as? Uri)// Update UI to reflect multiple images being shared
    }
}

companion object {
    private const val PLAIN_TEXT_MIME = "text/plain"
    private const val MEDIA_IMAGE_MIME = "image/"
    }
   }

我收到的错误信息：

Local extension properties are not allowed
Local extension properties are not allowed
This variable must either have a type annotation or be initialized
Unexpected tokens (use ';' to separate expressions on the same line)
Unresolved reference: first_imageView
<html>Unresolved reference. None of the following candidates is applicable because of receiver type mismatch:<br/>public operator fun &lt;T, R&gt; DeepRecursiveFunction&lt;TypeVariable(T), TypeVariable(R)&gt;.invoke(value: TypeVariable(T)): TypeVariable(R) defined in kotlin
Unresolved reference: second_imageView
<html>Unresolved reference. None of the following candidates is applicable because of receiver type mismatch:<br/>public operator fun &lt;T, R&gt; DeepRecursiveFunction&lt;TypeVariable(T), TypeVariable(R)&gt;.invoke(value: TypeVariable(T)): TypeVariable(R) defined in kotlin
Unused import directive
Unused import directive
Variable 'text' is never used
'when' with subject should be used

【问题讨论】：

标签： android kotlin android-activity

【解决方案1】：

我认为问题出在这里

 val first_ImageView.setImageURI(it)

你需要删除'val'

编辑：就像Gabe Sechan 提到的那样，您需要将布局绑定到您的 MainActivity（但前提是这些 TextViews 实际上在您的 activity_main.xml 中）：

将此字段添加到您的活动中：

private lateinit var binding: ActivityMainBinding

并在 onCreate() 中添加：

binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)

如果你想在 TextView 上调用 setImageUri()，请执行以下操作：

binding.yourTextView.setImageURI(it)

或者你可以写：

val first_ImageView = findViewById<View>(R.id.first_ImageView)

然后对找到的ImageView进行操作

编辑2：

您需要将方法更改为：

private fun handleSendText(intent: Intent) {
    intent.getStringExtra(Intent.EXTRA_TEXT)?.let {
       findViewById<View>(R.id.textView)?.text = it // Update UI to reflect text being shared
    }
}

    private fun handleSendImage(intent: Intent) {
        (intent.getParcelableExtra<Parcelable>(Intent.EXTRA_STREAM) as? Uri)?.let {
           findViewById<View>(R.id.first_ImageView)?.setImageURI(it)// Update UI to reflect image being shared
        }
    }
    
    private fun handleSendMultipleImages(intent: Intent) {
        intent.getParcelableArrayListExtra<Parcelable>(Intent.EXTRA_STREAM)?.let {
            findViewById<View>(R.id.first_ImageView)?.setImageURI(it(0) as? Uri)
            findViewById<View>(R.id.second_imageView)?.setImageURI(it(1) as? Uri)// Update UI to reflect multiple images being shared
        }
    }

【讨论】：

不仅如此——他还没有创建过 firstImageView。他需要类中的私有 val first_ImageView。或者他需要使用 ViewBinding，这似乎是他想要的
谢谢，但我很困惑。我会将 val first_ImageView = findViewById(R.id.first_ImageView) 放在哪里。另外，我会用 textView 和 second_ImageView 来做吗
我再次编辑了答案，以便更清楚您需要在哪里应用更改
还是同样的问题
我需要“创建id值资源“textView”吗？和我的小部件有关吗？

【解决方案2】：

没有视图绑定。您需要在活动文件中定义视图并在 setContentView 方法之后分配它们的值，然后您可以使用它来更新您的 UI。

`package com.example

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.content.Intent
import android.net.Uri
import android.os.Parcelable
import android.widget.TextView
import android.widget.ImageView

 class MainActivity : AppCompatActivity() {

  private lateinit var firstImage: ImageView;
  private lateinit var secondImage: ImageView;
  private lateinit var textView: TextView;

 override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
    textView = findViewById(R.id.textView)
    firstImage = findViewById(R.id.firstImage)
    secondImage = findViewById(R.id.secondImage)
    when {
        intent?.action == Intent.ACTION_SEND -> {
            when {
                intent.type == PLAIN_TEXT_MIME -> handleSendText(intent)
                intent.type?.startsWith(MEDIA_IMAGE_MIME) == true ->
                    handleSendImage(intent) // Handle single image being sent
            }
        }
        intent?.action == Intent.ACTION_SEND_MULTIPLE -> {
            when {
                intent.type?.startsWith(MEDIA_IMAGE_MIME) == true -> 
handleSendMultipleImages(intent)
            }
        }
    }
}

private fun handleSendText(intent: Intent) {
    intent.getStringExtra(Intent.EXTRA_TEXT)?.let {
        textView.text = it // Update UI to reflect text being shared
    }
}

private fun handleSendImage(intent: Intent) {
    (intent.getParcelableExtra<Parcelable>(Intent.EXTRA_STREAM) as? Uri)?.let {
        firstImage.setImageURI(it)// Update UI to reflect image being shared
    }
}

private fun handleSendMultipleImages(intent: Intent) {
    intent.getParcelableArrayListExtra<Parcelable>(Intent.EXTRA_STREAM)?.let {
        firstImage.setImageURI(it[0] as? Uri)
        secondImage.setImageURI(it[1] as? Uri)// Update UI to reflect multiple 
images being shared
    }
}

companion object {
    private const val PLAIN_TEXT_MIME = "text/plain"
    private const val MEDIA_IMAGE_MIME = "image/"
  }
}
`

XML 文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="vertical"
 tools:context=".MainActivity">

<TextView
    android:id="@+id/textView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Hello World!" />

<ImageView
    android:id="@+id/firstImage"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

<ImageView
    android:id="@+id/secondImage"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

您可以使用 ViewBindings 删除 findViewById 调用。 [https://developer.android.com/topic/libraries/view-binding]

【讨论】：

谢谢。我已经解决了问题。