RadioButtons-AGN HUB

 RadioButton in Kotlin (Android)

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Key Components

1. RadioButton: The individual buttons representing the options.

2. RadioGroup: Groups multiple RadioButton elements to enforce single selection.

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Basic Implementation

XML Layout

<LinearLayout

    xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:orientation="vertical"

    android:padding="16dp">

    <RadioGroup

        android:id="@+id/radioGroup"

        android:layout_width="match_parent"

        android:layout_height="wrap_content">

        <RadioButton

            android:id="@+id/radioButton1"

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:text="Option 1" />

        <RadioButton

            android:id="@+id/radioButton2"

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:text="Option 2" />

        <RadioButton

            android:id="@+id/radioButton3"

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:text="Option 3" />

    </RadioGroup>

    <Button

        android:id="@+id/buttonSubmit"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="Submit"

        android:layout_marginTop="16dp" />

</LinearLayout>

Kotlin Code

import android.os.Bundle

import android.widget.Button

import android.widget.RadioButton

import android.widget.RadioGroup

import android.widget.Toast

import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {

        super.onCreate(savedInstanceState)

        setContentView(R.layout.activity_main)

        val radioGroup: RadioGroup = findViewById(R.id.radioGroup)

        val buttonSubmit: Button = findViewById(R.id.buttonSubmit)

        buttonSubmit.setOnClickListener {

            // Get the selected RadioButton's ID

            val selectedId = radioGroup.checkedRadioButtonId

            if (selectedId != -1) {

                // Find the RadioButton by its ID

                val selectedRadioButton: RadioButton = findViewById(selectedId)

                val selectedText = selectedRadioButton.text

                Toast.makeText(this, "Selected: $selectedText", Toast.LENGTH_SHORT).show()

            } else {

                Toast.makeText(this, "No option selected", Toast.LENGTH_SHORT).show()

            }

        }

    }

}

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Key Properties and Methods

1. RadioButton:

• isChecked: Boolean property to check if the button is selected.

• text: Gets or sets the text of the button.

2. RadioGroup:

• checkedRadioButtonId: Returns the ID of the selected RadioButton. If none is selected, it returns -1.

• setOnCheckedChangeListener: Listens for selection changes.

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Advanced Features

Set Default Selection

You can set a default selected RadioButton programmatically:

radioGroup.check(R.id.radioButton2) // Sets "Option 2" as selected

Handle Change Events

Listen for changes in the selected RadioButton:

radioGroup.setOnCheckedChangeListener { group, checkedId ->

    val selectedRadioButton: RadioButton = findViewById(checkedId)

    Toast.makeText(this, "Selected: ${selectedRadioButton.text}", Toast.LENGTH_SHORT).show()

}

Deselect All RadioButtons

Clear the selection programmatically:

radioGroup.clearCheck()

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Styling and Customization

1. Custom Text Color:

2. <RadioButton

3.     android:layout_width="wrap_content"

4.     android:layout_height="wrap_content"

5.     android:text="Custom Option"

6.     android:textColor="@color/black" />

7. Custom Button Drawable: Replace the default radio button with a custom drawable:

8. <RadioButton

9.     android:layout_width="wrap_content"

10.     android:layout_height="wrap_content"

11.     android:button="@drawable/custom_radio_button" />

12. Vertical or Horizontal Alignment: Use android:orientation in the RadioGroup to arrange buttons:

13. <RadioGroup

14.     android:layout_width="match_parent"

15.     android:layout_height="wrap_content"

16.     android:orientation="horizontal">

17.     <!-- RadioButtons -->

18. </RadioGroup>

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Example: Dynamic RadioButtons

Kotlin Code

Create RadioButton elements programmatically:

val radioGroup: RadioGroup = findViewById(R.id.radioGroup)

// Add dynamic RadioButtons

val options = listOf("Dynamic Option 1", "Dynamic Option 2", "Dynamic Option 3")

for (option in options) {

    val radioButton = RadioButton(this).apply {

        text = option

        id = View.generateViewId() // Generate a unique ID

    }

    radioGroup.addView(radioButton)

}

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Common Use Cases

1. Forms: Single-choice questions like gender, subscription type, etc.

2. Settings: Selecting preferences (e.g., dark mode or light mode).

3. Filters: Choosing one filter category from a list.