package com.example.colormyviews
import android.graphics.Color
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.Button
import android.widget.TextView
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
setListeners()
}
private fun setListeners(){
val boxOneText = findViewById<TextView>(R.id.box_one_text)
val boxTwoText = findViewById<TextView>(R.id.box_two_text)
val boxThreeText = findViewById<TextView>(R.id.box_three_text)
val boxFourText = findViewById<TextView>(R.id.box_four_text)
val boxFiveText = findViewById<TextView>(R.id.box_five_text)
val rootConstraintLayout = findViewById<View>(R.id.info_text)
val redButton = findViewById<Button>(R.id.red_button)
val greenButton = findViewById<Button>(R.id.green_button)
val yellowButton = findViewById<Button>(R.id.yellow_button)
val clickableViews: List<View> =
listOf(
boxOneText, boxTwoText, boxThreeText,
boxFourText, boxFiveText, rootConstraintLayout,
redButton, greenButton, yellowButton
)
for (item in clickableViews){
item.setOnClickListener{makeColored(it)}
}
}
private fun makeColored(view: View){
when (view.id) {
// Boxes using Color class colors for the background
R.id.box_one_text -> view.setBackgroundColor(Color.DKGRAY)
R.id.box_two_text -> view.setBackgroundColor(Color.GRAY)
R.id.box_three_text -> view.setBackgroundColor(Color.BLUE)
R.id.box_four_text -> view.setBackgroundColor(Color.MAGENTA)
R.id.box_five_text -> view.setBackgroundColor(Color.BLUE)
R.id.red_button -> box_three_text.setBackgroundResource(R.color.my_red)
R.id.yellow_button -> box_four_text.setBackgroundResource(R.color.my_yellow)
R.id.green_button -> box_five_text.setBackgroundResource(R.color.my_green)
else -> view.setBackgroundColor(Color.LTGRAY)
}
}
}
XML代码。
<?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/constraint_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:id="@+id/box_one_text"
style="@style/whiteBox"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginLeft="16dp"
android:layout_marginTop="@dimen/margin_wide"
android:layout_marginRight="16dp"
android:text="@string/box_one"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/box_two_text"
style="@style/whiteBox"
android:layout_width="130dp"
android:layout_height="130dp"
android:layout_marginStart="16dp"
android:layout_marginTop="16dp"
android:text="@string/box_two"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/box_one_text" />
<TextView
android:id="@+id/box_three_text"
style="@style/whiteBox"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="@dimen/margin_wide"
android:layout_marginEnd="@dimen/margin_wide"
android:text="@string/box_three"
app:layout_constraintBottom_toTopOf="@+id/box_four_text"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="@+id/box_two_text"
app:layout_constraintTop_toTopOf="@+id/box_two_text" />
<TextView
android:id="@+id/box_four_text"
style="@style/whiteBox"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="@dimen/margin_wide"
android:layout_marginTop="@dimen/margin_wide"
android:layout_marginEnd="@dimen/margin_wide"
android:layout_marginBottom="@dimen/margin_wide"
android:text="@string/box_four"
app:layout_constraintBottom_toTopOf="@+id/box_five_text"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="@+id/box_two_text"
app:layout_constraintTop_toBottomOf="@+id/box_three_text" />
<TextView
android:id="@+id/box_five_text"
style="@style/whiteBox"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="@dimen/margin_wide"
android:layout_marginEnd="@dimen/margin_wide"
android:text="@string/box_five"
app:layout_constraintBottom_toBottomOf="@+id/box_two_text"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="@+id/box_two_text"
app:layout_constraintTop_toBottomOf="@+id/box_four_text" />
<TextView
android:id="@+id/label_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:fontFamily="@font/roboto"
android:text="@string/how_to_play"
android:textSize="24sp"
android:textStyle="bold"
app:layout_constraintBaseline_toBaselineOf="@+id/info_text"
app:layout_constraintStart_toStartOf="parent" />
<TextView
android:id="@+id/info_text"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginTop="16dp"
android:fontFamily="@font/roboto"
android:text="@string/tap_the_boxes_and_buttons"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toEndOf="@+id/label_text"
app:layout_constraintTop_toBottomOf="@+id/box_two_text"
app:layout_constraintVertical_bias="0.0" />
<Button
android:id="@+id/red_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:text="@string/button_red"
app:layout_constraintBaseline_toBaselineOf="@+id/yellow_button"
app:layout_constraintEnd_toStartOf="@+id/yellow_button"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent" />
<Button
android:id="@+id/yellow_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginEnd="16dp"
android:layout_marginBottom="16dp"
android:text="@string/button_yellow"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toStartOf="@+id/green_button"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toEndOf="@+id/red_button"
app:layout_constraintTop_toBottomOf="@+id/info_text"
app:layout_constraintVertical_bias="1.0"/>
<Button
android:id="@+id/green_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="16dp"
android:text="@string/button_green"
app:layout_constraintBaseline_toBaselineOf="@+id/yellow_button"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toEndOf="@+id/yellow_button" />
</androidx.constraintlayout.widget.ConstraintLayout>
在makeColored((函数中，同时对box_three_text、box_four_text、box_five_text调用setBackgroundResource((。它向我抛出了一个"未解决的引用错误"。然而，具有相同名称的id已在XML文件中声明。我不明白问题出在哪里，请帮助我了解发生了什么，以及为什么它无法读取Mainactivity.kt中的id，该id已在Mainactivity.xm中声明。
而不是id使用引用
R.id.red_button -> boxThreeText.setBackgroundResource(R.color.my_red)
R.id.yellow_button -> boxFourText.setBackgroundResource(R.color.my_yellow)
R.id.green_button -> boxFiveText.setBackgroundResource(R.color.my_green)
并使这些按钮全局可变。如果你使用kotlin-synthetic，你可以直接使用id，但我在你的代码中看不到任何这样的导入。(无论如何，你都不应该使用合成的kotlin，因为kotlin扩展插件已被弃用(
您必须定义全局变量，而不是使用id，如下所示：
class MainActivity : AppCompatActivity() {
private lateinit var boxOneText: View
private lateinit var boxTwoText: View
private lateinit var boxThreeText: View
private lateinit var boxFourText: View
private lateinit var boxFiveText: View
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
setListeners()
}
private fun makeColored(view: View) {
when (view.id) {
R.id.box_one_text -> view.setBackgroundColor(Color.DKGRAY)
R.id.box_two_text -> view.setBackgroundColor(Color.GRAY)
R.id.box_three_text -> view.setBackgroundColor(Color.BLUE)
R.id.box_four_text -> view.setBackgroundColor(Color.MAGENTA)
R.id.box_five_text -> view.setBackgroundColor(Color.BLUE)
R.id.red_button -> boxThreeText.setBackgroundResource(R.color.my_red)
R.id.yellow_button -> boxFourText.setBackgroundResource(R.color.my_yellow)
R.id.green_button -> boxFiveText.setBackgroundResource(R.color.my_green)
else -> view.setBackgroundColor(Color.LTGRAY)
}
}
private fun setListeners() {
boxOneText = findViewById<TextView>(R.id.box_one_text)
boxTwoText = findViewById<TextView>(R.id.box_two_text)
boxThreeText = findViewById<TextView>(R.id.box_three_text)
boxFourText = findViewById<TextView>(R.id.box_four_text)
boxFiveText = findViewById<TextView>(R.id.box_five_text)
val rootConstraintLayout = findViewById<View>(R.id.constraint_layout)
val redButton = findViewById<Button>(R.id.red_button)
val greenButton = findViewById<Button>(R.id.green_button)
val yellowButton = findViewById<Button>(R.id.yellow_button)
val clickableViews: List<View> =
listOf(
boxOneText, boxTwoText, boxThreeText,
boxFourText, boxFiveText, rootConstraintLayout,
redButton, greenButton, yellowButton
)
for (item in clickableViews) {
item.setOnClickListener { makeColored(it) }
}
}
}