Android cardview，使用切换监听器更改背景颜色

Question

I have a cardview with a switch inside. When the switch is on, I want to change the background color of the card to green, when is off(by default it is) instead is red. I also need to save the switch state locally, so when I open the app again, it remain in the last position it was. I don't know if it's ok doing all the code for that in the adapter..I'm using 2 fragment, and the cardview is inside one of them, in a listview. I think I have to use

// paidSwitch is the switch in the cardview paidSwitch.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() { @Override public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) { paidCard.setCardBackgroundColor(??? I need to get my R.color.green value here);

This code is inside the getView method in the adapter class. Each cardview in the list has it's own switch. I attach a picture of the fragments, so it's easier to understand. ps. How can I reduce the size(screen size) of the picture when I post some photo here?

Answer 1

This should work :

    final int greenBackgroundColor = ContextCompat.getColor(this, R.color.my_red_color);
    final int redBackgroundColor = ContextCompat.getColor(this, R.color.my_green_color);
    switch.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
        @Override
        public void onCheckedChanged(CompoundButton compoundButton, boolean b) {
            if (b){
                cardView.setCardBackgroundColor(greenBackgroundColor);
            }
            else{
                cardView.setCardBackgroundColor(redBackgroundColor);
            }

        }
    });

And set the default card background with :

app:cardBackgroundColor="@color/white"

Hope this helps

Answer 2

To save state locally, you can use SharedPrefrences or Paper library. I personally prefer Paper.

You can use it like so

//Init Paper
Paper.init(this);

//save switch state
Paper.book().write("key1", "value1");
Paper.book().write("key2", "value2");

// key being the switch Indentifier, value being the state of the specific switch

//save switch state
String value1 = Paper.book().read("key1");
String value2= Paper.book().read("key2");

//delete all saved record
Paper.book().destroy();

EDIT --

This logic of Saving the state can be implemented after the if-else of the onCheckedChanged, like so

if (isChecked){
    //line of code to change color
   ...
}
else{
    //line of code to change color
   ...
}

 //line of code to save state
 Paper.book().write("position", isChecked);

This logic of Reading the state & Setting to switches can be implemented in onResume (and onCreate too, if needed) , like so

paidSwitchAtPosition.setChecked(Paper.book().read("position"));