I have a group of radio buttons to toggle the background color of the textview on an app. Here is the XML for the buttons and the textview

<TextView
            android:id="@ id/calcScreen"
            android:layout_width="wrap_content"
            android:layout_height="500dp"
            android:fontFamily="monospace"
            android:text="0"
            android:textSize="48sp" />

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="horizontal">

            <RadioGroup
                android:id="@ id/bgColorChangeGRP"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="horizontal"
                android:paddingHorizontal="14dp">

                <RadioButton
                    android:id="@ id/_FF0000"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:onClick="onRadioButtonClicked"
                    android:text="Red background"
                    android:textSize="12sp" />

                <RadioButton
                    android:id="@ id/_00FF00"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:onClick="onRadioButtonClicked"
                    android:text="Green background"
                    android:textSize="12sp" />

                <RadioButton
                    android:id="@ id/_0000FF"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:onClick="onRadioButtonClicked"
                    android:text="Blue background"
                    android:textSize="12sp" />
            </RadioGroup>

        </LinearLayout>

As you can see, I have a onClick method added called onRadioButtonClicked, here is the code for that function:

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

    fun onRadioButtonClicked(v: View){
        val textView = findViewById<TextView>(R.id.calcScreen)
        if (v is RadioButton) {
            val checked = v.isChecked
            when(v.getId()){
                R.id._0000FF ->
                    if (checked) {
                        textView.setBackgroundColor(0xFF0000)
                    }
                R.id._00FF00 ->
                    if (checked) {
                        textView.setBackgroundColor(0x00FF00)
                    }
                R.id._0000FF ->
                    if (checked) {
                        textView.setBackgroundColor(0x0000FF)
                    }
            }
        }
    }

}

Whenever I click a button nothing happens. I tried adding a print statement in testing but did not see any output in the text console. I followed the android tutorial but do not seem to get the desired output. I think it has something to do with how the onRadioButtonClicked function is getting the id's but am not 100% sure. Any tips would be appreciated.

CodePudding user response：

if (checked) {
       textView.setBackgroundColor(Color.parseColor("#FFFFFF"))
 }

try to use it as

CodePudding user response：

To clarify why your original solution wasn't working. because you made your button transparent. The first byte is the alpha.

So your colors should have value like: 0xFFFF0000 to make your colors visible. FF at the start is key.

So your code would look something like this:

fun onRadioButtonClicked(v: View){
        val textView = findViewById<TextView>(R.id.calcScreen)
        if (v is RadioButton) {
            val checked = v.isChecked
            when(v.getId()){
                R.id._FF0000 ->
                    if (checked) {
                        textView.setBackgroundColor(0xFFFF0000.toInt())
                    }
                R.id._00FF00 ->
                    if (checked) {
                        textView.setBackgroundColor(0xFF00FF00.toInt())
                    }
                R.id._0000FF ->
                    if (checked) {
                        textView.setBackgroundColor(0xFF0000FF.toInt())
                    }
            }
        }
    }