Multiple Switch Buttons

Question

I am new to Android development and am having a question about multiple switch buttons, how to retrieve values ​​smartly, and make this data available for other activities?

Currently, I am implemented the save of the button state and retrieval of the information found in the current activity as followed:

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

    switchButtonOne = findViewById(R.id.switchButtonOne);
    switchButtonOne.setChecked(true);

    switchButtonTwo = findViewById(R.id.switchButtonTwo);
    switchButtonTwo.setChecked(false);

    //...... (In total there are 5 switch buttons)

    //switchButtonOne
    switchButtonOne.setOnCheckedChangeListener((compoundButton, isChecked) -> {
        if(isChecked){
            stringArrayList.add("1");
        }else {
            stringArrayList.remove("1");
        }
        getArray(stringArrayList);
        //SAVE
        sharedPreferences[0] = PreferenceManager
                .getDefaultSharedPreferences(getApplicationContext());
        SharedPreferences.Editor editor = sharedPreferences[0].edit();
        editor.putBoolean("1", switchButtonOne.isChecked());
        editor.commit();
    });
    switchButtonOne.setChecked(sharedPreferences[0].getBoolean("1", false));

    //switchButtonTwo
    switchButtonTwo.setOnCheckedChangeListener((compoundButton, isChecked) -> {
        if(isChecked){
            stringArrayList.add("2");
        }else {
            stringArrayList.remove("2");
        }
        getArray(stringArrayList);
        //SAVE
        sharedPreferences[0] = PreferenceManager
                .getDefaultSharedPreferences(getApplicationContext());
        SharedPreferences.Editor editor = sharedPreferences[0].edit();
        editor.putBoolean("2", switchButtonTwo.isChecked());
        editor.commit();
    });
    //.......
}

I am sure there is a more efficient way to implement this and I would gladly appreciate effective resources to learn the best practices of making information and Activity state available between Activities.

Big thanks in advance

Answer 1

One option is to use only one listener for all five buttons. You would do this like so:

public class MyActivity extends Activity implements CompoundButton.OnCheckedChangeListener {
    Switch[] buttons;

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

        buttons = new Switch[5];
        Switch switchButtonOne = findViewById(R.id.switchButtonOne);
        switchButtonOne.setOnCheckedChangeListener(this);
        switchButtonOne.setChecked(sharedPreferences[0].getBoolean("1", false));
        buttons[0] = switchButtonOne;

        Switch switchButtonTwo = findViewById(R.id.switchButtonTwo);
        switchButtonTwo.setOnCheckedChangeListener(this);
        switchButtonTwo.setChecked(sharedPreferences[1].getBoolean("2", false));
        buttons[1] = switchButtonTwo;

        //...... (In total there are 5 switch buttons)
    }

    @Override
    public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
        int index;
        switch (buttonView.getId()) {
            case R.id.switchButtonOne:
                index = 0;
                break;
            case R.id.switchButtonTwo:
                index = 1;
                break;
                ...
        }
        if (isChecked) {
            stringArrayList.add(String.valueOf(index + 1));
        } else {
            stringArrayList.remove(String.valueOf(index + 1));
        }
        getArray(stringArrayList);
        //SAVE
        sharedPreferences = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
        SharedPreferences.Editor editor = sharedPreferences[index].edit();
        editor.putBoolean(String.valueOf(index + 1), buttons[index].isChecked());
        editor.commit();
    }
}

At this point the code is not much shorter than yours, however, as soon as you add your other three buttons, you will see than the code for all buttons ends up being considerably shorter and more concise.

It would be great to have a BooleanArray for the SharedPreferences, however, such a class does not exist. A workaround can be found here.

EDIT

Looking at your question and your full code again, I would suggest a different approach. You don't need any OnCheckedChangeListener at all. Simply save the state of your buttons whenever the activity is left (onPause) and restore state once the activity is resumed (onResume). A side effect is that the code gets much shorter.

public class MainActivity extends Activity {
    Switch[] buttons;
    int numberOfButtons = 5;
    SharedPreferences sharedPreferences;

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

        buttons = new Switch[numberOfButtons];
        sharedPreferences = getSharedPreferences("YourPreferenceName", MODE_PRIVATE);

        for (int i = 0; i < numberOfButtons; i++) {
            buttons[i] = findViewById(getResources().getIdentifier("switchButton" + String.valueOf(i + 1), "id", getPackageName()));
        }
    }

    public void onPause() {
        super.onPause();
        for (int i = 0; i < numberOfButtons; i++) {
            SharedPreferences.Editor editor = sharedPreferences.edit();
            editor.putBoolean(String.valueOf(i + 1), buttons[i].isChecked());
            editor.apply();
        }
    }

    public void onResume(){
        super.onResume();
        for (int i = 0; i < numberOfButtons; i++) {
            buttons[i].setChecked(sharedPreferences.getBoolean(String.valueOf(i + 1), false));
        }
    }
}

Please note that, in your layout xml, you have to change the ids of your switches to the following: switchButton1, ..., switchButton5.

Answer 2

You can Implement CompoundButton.OnCheckedChangeListener for whole activity and then set listener for all switch you have used.Handle all switch in single callback onCheckedChanged.

public class SwitchActivity extends Activity implements CompoundButton.OnCheckedChangeListener {
    Switch switchButtonOne;
    Switch switchButtonTwo;

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState, @Nullable PersistableBundle persistentState) {

        super.onCreate(savedInstanceState, persistentState);
        switchButtonOne = findViewById(R.id.switchButtonOne);
        switchButtonOne.setChecked(true);

        switchButtonTwo = findViewById(R.id.switchButtonTwo);
        switchButtonTwo.setChecked(false);

        switchButtonOne.setOnCheckedChangeListener(this);
        switchButtonTwo.setOnCheckedChangeListener(this);
    }

    @Override
    public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
        switch (buttonView.getId()) {
            case R.id.switchButtonOne:
                //Handle Code for switchButtonOne
                break;
            case R.id.switchButtonTwo:
                //Handle Code for switchButtonOne
                break;
        }
    }
}