How to pass data between fragments of an Activity in Android app

This blog demonstrates how to pass values of a variable between two fragments of a single activity. The blog will mainly include the demonstration of passing values between fragments while using BottomSheet Navigation as done in PSLab Android application.

This blog contains the work done by me in the Lux Meter instrument of the PSLab Android app of passing data from LuxMeterConfiguration fragment to LuxMeterData fragment as shown in the featured image to set the high limit for the pointer and to set the update period of the Lux Sensor. The blog will solve the difficult task of communication between two fragments of a single activity. For passing data between multiple fragments of different activities, refer to [1].

How to pass data between fragments?

In this blog, I will pass data from Fragment 2 to Fragment 1 only. But vice versa or passing data from both the fragments can also be made using the same given approach.

  • First, make a static method in Fragment 1 which can set the parameters i.e. the value of the variables as soon as the fragment is inflated as follow
public static void setParameters(int one, int two, int three) {
        Fragment1.firstValue = one;
        Fragment1.secondValue = two;
        Fragment1.thirdValue = three;
    }
  • Now, there is one point to mark that Fragment 1 will be inflated only when Fragment 2 gets destroyed. Else, other than default inflation of Fragment 1, there is no way Fragment 1 can be inflated after navigating to Fragment 2.
  • So, override the OnDestroy() method of Fragment 2 and use the setParameters() method to set the value of variables from Fragment 2 to be used in Fragment 1.
@Override
    public void onDestroyView() {
        super.onDestroyView();
        highValue = getValueFromText(highLimit, 0, highLimitMax);
        updatePeriodValue = getValueFromText(updatePeriod, updatePeriodMin, updatePeriodMax + 100);
        Fragment1.setParameters(selectedSensor, highValue, updatePeriodValue);
    }

Here, the highValue, updatePeriodValue and selectedSensor are the variables being used in the Lux Meter fragment in PSLab Android app. But they can be replaced by the necessary variables as per the app.

So, in this way, we can pass data between the fragments of the same Activity in an Android application. Above demonstration can be extended in passing values between multiple fragments of the same Activity by creating different methods in different fragments.

Resources

  1. Blog on how to pass data between fragments of different/same activities: https://www.journaldev.com/14207/android-passing-data-between-fragments