Android CheckBox Tutorial

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1- Android CheckBox

In Android, CheckBox is a button with two states,  checked and unchecked. It is a basic component and frequently used in Android applications.
Basically, you can use multiple CheckBoxes in the application to allow users to select one or more options in a set of values.
By default, the CheckBoxes have the  unchecked state, so you can change its state via the  android:checked attribute.
<CheckBox
    android:id="@+id/someId"
    android:checked="true"
    ... />
Some important attributes of CheckBox:
Attribute Description
android:checked Specify the current status for the CheckBox.
android:gravity Align the text of the CheckBox. The possible values are left, right, center, top, ...
android:text Set text content for CheckBox.
android:textColor Set the color of the text.
android:textSize Set font size of text.
android:textStyle Set text style (bold, italic, bolditalic).
android:background Set the background color for the CheckBox.
android:padding Set padding for CheckBox.
android:onClick The name of the method will be called when the user clicks on CheckBox.

toggle()

All 4 classes of ToggleButton, CheckBox, RadioButton, Switch are subclasses of CompoundButton, so they inherit the toggle() method, which is the commonly used method to change their state from Checked (ON) to Unchecked (OFF), and vice versa.
CompoundButton button = (CheckBox) findViewById(R.id.checkBox);

button.toggle();

2- CheckBox Events

There are quite a few events related to a CheckBox, but here are two events used most often:
  • checkBox.setOnClickListener(View.OnClickListener)
  • checkBox.setOnCheckedChangeListener(CompoundButton.OnCheckedChangeListener)

On Click Event:

The event occurs when the user clicks on the CheckBox, similarly when the user clicks on a Button.
CheckBox chk = (CheckBox) findViewById(R.id.chk1);

chk.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        boolean checked = ((CheckBox) v).isChecked();
        // Check which checkbox was clicked
        if (checked){
            // Your code
        }
        else{
            // Your code
        }
    }
});

On Checked Change Event:

The event occurs when the CheckBox changes its state, due to the user's action or the effect of calling the  checkBox.setChecked(newState) method.
CheckBox chk = (CheckBox) findViewById(R.id.chk1);

chk.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
    @Override
    public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
        if(isChecked)  {
           // Your code
        } else {
           // Your code
        }
    }
});

3- An example of the CheckBox

Now let's take a quick look before we start:
The interface of the example application will look like this:
Note: If you are interested in the steps to design the interface of this application, please check out the appendix at the end of the article.
activity_main.xml
<?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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/textView"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginLeft="16dp"
        android:layout_marginTop="35dp"
        android:layout_marginEnd="16dp"
        android:layout_marginRight="16dp"
        android:text="What programming languages do you like?"
        android:textSize="18sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <CheckBox
        android:id="@+id/checkBox_checkAll"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginLeft="16dp"
        android:layout_marginTop="39dp"
        android:layout_marginEnd="16dp"
        android:layout_marginRight="16dp"
        android:text="(Check All)"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView" />

    <CheckBox
        android:id="@+id/checkBox_ccpp"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginLeft="16dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="16dp"
        android:layout_marginRight="16dp"
        android:text="C/C++"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/checkBox_checkAll" />

    <CheckBox
        android:id="@+id/checkBox_csharp"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginLeft="16dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="16dp"
        android:layout_marginRight="16dp"
        android:text="CSharp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/checkBox_ccpp" />

    <CheckBox
        android:id="@+id/checkBox_java"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginLeft="16dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="16dp"
        android:layout_marginRight="16dp"
        android:text="Java"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/checkBox_csharp" />

    <Button
        android:id="@+id/button_showResult"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:text="Show Result"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/checkBox_java" />
</androidx.constraintlayout.widget.ConstraintLayout>
MainActivity.java
package com.example.checkboxexample;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    private CheckBox checkBoxCheckAll;
    private CheckBox checkBoxCcpp;
    private CheckBox checkBoxCsharp;
    private CheckBox checkBoxJava;

    private Button buttonShowResult;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        this.checkBoxCheckAll = (CheckBox) this.findViewById(R.id.checkBox_checkAll);
        this.checkBoxCcpp = (CheckBox) this.findViewById(R.id.checkBox_ccpp);
        this.checkBoxCsharp = (CheckBox) this.findViewById(R.id.checkBox_csharp);
        this.checkBoxJava = (CheckBox) this.findViewById(R.id.checkBox_java);

        this.buttonShowResult = (Button) this.findViewById(R.id.button_showResult);

        this.buttonShowResult.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                showResult();
            }
        });

        this.checkBoxCheckAll.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                checkAllCheckedChange(isChecked);
            }
        });
    }

    private void showResult()  {
        String message = null;
        if(this.checkBoxCcpp.isChecked()) {
            message =  this.checkBoxCcpp.getText().toString();
        }
        if(this.checkBoxCsharp.isChecked()) {
            if(message== null)  {
                message =  this.checkBoxCsharp.getText().toString();
            } else {
                message += ", " + this.checkBoxCsharp.getText().toString();
            }
        }
        if(this.checkBoxJava.isChecked()) {
            if(message== null)  {
                message =  this.checkBoxJava.getText().toString();
            } else {
                message += ", " + this.checkBoxJava.getText().toString();
            }
        }
        message = message == null? "You select nothing": "You select: " + message;
        Toast.makeText(this, message, Toast.LENGTH_LONG).show();
    }

    // When "Check All" change state.
    private void checkAllCheckedChange(boolean isChecked)  {
        this.checkBoxCsharp.setChecked(isChecked);
        this.checkBoxCcpp.setChecked(isChecked);
        this.checkBoxJava.setChecked(isChecked);
    }
}

4- Appendix: Interface design

Here are some steps to design the application interface (of the above example).
Set ID, Text for the component in the interface:
  • textView: textSize="18sp"

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