Using CheckBox's with button and switch

Issue

I am trying to show toast with the color name of the CheckBox that selected, but when I click on the button, nothing happens, I tried to use the LinearLayout as a parent of all views to get the id of the chosen Checkbox, first I tried to create it as a Linearlayout in main activity but the app is stopped when I choose one checkbox and click on the button, then I changed it to a View and cast it to LinearLayout

here's my code

public class MainActivity extends AppCompatActivity {

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

        View view = (LinearLayout)findViewById(R.id.view);

        Button btn = findViewById(R.id.button1);

        CheckBox chk1 = findViewById(R.id.chk1);
        CheckBox chk2 = findViewById(R.id.chk2);
        CheckBox chk3 = findViewById(R.id.chk3);

        btn.setOnClickListener(v -> {

            switch (view.getId()) {
                case R.id.chk1:
                    if (chk1.isChecked())
                        Toast.makeText(MainActivity.this, "Green", Toast.LENGTH_LONG).show();
                    break;

                case R.id.chk2:

                    if (chk2.isChecked())
                        Toast.makeText(MainActivity.this, "Orange", Toast.LENGTH_LONG).show();
                    break;

                case R.id.chk3:
                    if (chk3.isChecked())
                        Toast.makeText(MainActivity.this, "Orange", Toast.LENGTH_LONG).show();

                    break;
                default:
            }
        });

    }

The layout

<?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"
    android:id="@+id/view"
    >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:layout_gravity="center"
        android:text="@string/app_name"
        android:textColor="@color/black"
        android:textAlignment="center"
        android:textSize="24sp"
        />

    <CheckBox
        android:id="@+id/chk1"
        android:text="Green"
        android:textSize="33sp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        >

    </CheckBox>

    <CheckBox
        android:id="@+id/chk2"
        android:text="Orange"
        android:textSize="33sp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        >

    </CheckBox>

    <CheckBox
        android:id="@+id/chk3"
        android:text="Blue"
        android:textSize="33sp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        >

    </CheckBox>

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:layout_gravity="center"
        android:text="@string/button1"
        android:textAllCaps="false"
        android:textSize="24sp"
        >

    </Button>

</LinearLayout>

Solution

btn.setOnClickListener(v -> {
    switch (view.getId()) {
        case R.id.chk1:
            if (chk1.isChecked())
                Toast.makeText(MainActivity.this, "Green", Toast.LENGTH_LONG).show();
            break;
        case R.id.chk2:

            if (chk2.isChecked())
                Toast.makeText(MainActivity.this, "Orange", Toast.LENGTH_LONG).show();
            break;
        case R.id.chk3:
            if (chk3.isChecked())
                Toast.makeText(MainActivity.this, "Orange", Toast.LENGTH_LONG).show();
            break;
        default:
    }
});

Root cause

When users click on btn button, you check whether the view has the same id with one of the CheckBox or not, but it always false because they are different view with different id. That why you do not see any toast on screen.

Solution

No need to use switch-case, just use if statement, like this.

btn.setOnClickListener(v -> {
    StringBuilder color = new StringBuilder();

    if (chk1.isChecked()) {
        color.append(chk1.getText().toString()).append(" ");
    }

    if (chk2.isChecked()) {
        color.append(chk2.getText().toString()).append(" ");
    }

    if (chk3.isChecked()) {
        color.append(chk3.getText().toString());
    }

    Toast.makeText(MainActivity.this, color.toString().trim(), Toast.LENGTH_LONG).show();
});

Note: If you want the users can select one color at a time, please use RadioButton instead CheckBox.

Update: If you really want to use switch-case and CheckBox, then here is a solution for you.

public class MainActivity extends AppCompatActivity {

    private CheckBox latestCheckedCheckBox;
    private View.OnClickListener onCheckBoxClickedListener = new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            CheckBox checkBox = (CheckBox) v;
            if (checkBox.isChecked()) {
                latestCheckedCheckBox = checkBox;
            }
        }
    };

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

        View view = (LinearLayout) findViewById(R.id.view);

        Button btn = findViewById(R.id.button1);

        CheckBox chk1 = findViewById(R.id.chk1);
        CheckBox chk2 = findViewById(R.id.chk2);
        CheckBox chk3 = findViewById(R.id.chk3);

        chk1.setOnClickListener(onCheckBoxClickedListener);
        chk2.setOnClickListener(onCheckBoxClickedListener);
        chk3.setOnClickListener(onCheckBoxClickedListener);

        btn.setOnClickListener(v -> {
            if (latestCheckedCheckBox == null) {
                return;
            }

            String color = "";
            switch (latestCheckedCheckBox.getId()) {
                case R.id.chk1:
                    if (chk1.isChecked()) {
                        color = chk1.getText().toString();
                        Toast.makeText(MainActivity.this, color, Toast.LENGTH_LONG).show();
                    }
                    break;
                case R.id.chk2:
                    if (chk2.isChecked()) {
                        color = chk2.getText().toString();
                        Toast.makeText(MainActivity.this, color, Toast.LENGTH_LONG).show();
                    }
                    break;
                case R.id.chk3:
                    if (chk3.isChecked()) {
                        color = chk3.getText().toString();
                        Toast.makeText(MainActivity.this, color, Toast.LENGTH_LONG).show();
                    }
                    break;
                default:
                    break;
            }
        });
    }
}

Answered By - Son Truong