Validating multiple checkboxes in linear layout

Question

I am trying to make an app that lists all the predefined tasks a person has to do daily. To mark them I'm using checkboxes in vertical linearlayout. I'm using for loop to iterate through the layout. I want that if a checkbox is checked, an integer (total) is incremented by 1 and if it is unchecked then the integer remains same. Here is the method:

CheckBox checkBox151, checkBox152, checkBox153;
LinearLayout sundayLayout;

int total = 0;
int[] boxState = {2, 2, 2, 2, 2, 2, 2};


public int formIsValid(LinearLayout layout) {
    boolean wasChecked = false;

    for (int i = 0; i < layout.getChildCount(); i++) {
        View v = layout.getChildAt(i);

        if (v instanceof CheckBox) {
            if (((CheckBox) v).isChecked() && boxState[i] == 2 && wasChecked == false) {
                total++;
                boxState[i] = 0;
                wasChecked = true;

            } else if (boxState[i] == 1 && wasChecked == true) {
                total = total - 1;
                boxState[i] = 2;

            } else if (boxState[i] == 0 && wasChecked == false) {
                boxState[i] = 2;
            }
        }
    }
    return total;
}

I tried various logic statements, but what I get eventually is either the number getting incremented ok but decremented when I check the box again (I want it to decrement when unchecked, and increment when checked ONLY), but when I try this the app crashes due to bad logic statements.

Instant help needed, And thanks in advance...

Answer 1

This is the main purpose of Listeners. They watch the changes you make on components.

In your case you should use a CompoundButton.OnCheckedChangeListener

In your case, using a listener would let you only track the relevant changes (check / uncheck). Since it would be only called when a check / uncheck event has been triggered.

You also don't need to "validate" the values of the checkboxes by looping every time on the LinearLayout to be able to increment / decrement the counter value.

Here's how you would use it in your case:

public class MyActivity extends AppCompatActivity implements CompoundButton.OnCheckedChangeListener {

    private int counter;

    @Override
    protected void onCreate (Bundle savedInstanceState) {
        super.onCreate (savedInstanceState);

        // ........

        CheckBox checkBox1 = findViewById (R.id.checkbox1);
        CheckBox checkBox2 = findViewById (R.id.checkbox2);
        CheckBox checkBox3 = findViewById (R.id.checkbox3);

        checkBox1.setOnCheckedChangeListener (this);
        checkBox2.setOnCheckedChangeListener (this);
        checkBox3.setOnCheckedChangeListener (this);
    }

    @Override
    public void onCheckedChanged (CompoundButton buttonView, boolean isChecked) {
        if (isChecked) {
            counter ++;
        } else {
            counter --;
        }
    }
}

Then when submitting your form, just grab the counter variable and do whatever you want with it.

EDIT: Regarding the 175 requirements, the concept stays the same. You'll register a listener to all of them.

The OnCreate method becomes:

@Override
protected void onCreate (Bundle savedInstanceState) {
    super.onCreate (savedInstanceState);

    // ........
    // For each one of the 7 layouts you'll call the following (better create a method containing the below)
    for (int i = 0; i < layout.getChildCount(); i++) {
        View v = layout.getChildAt(i);

        if (v instanceof CheckBox) {
            ((CheckBox)v).setOnCheckedChangeListener (this);
        }
    }