Discussion of LiveData and Android life cycle

LiveData is a commonly used data holding class in Android development, which is closely related to the Android life cycle.This article will explore the correlation between Livedata in the Android life cycle and provide some Java code examples. First, let's understand what LiveData is.LiveData is an observed data holding class that can perceive the life cycle in the application and ensure that it is updated only when the activity or fragment is in an active state.This means that LiveData can help developers automatically update the UI when the data changes without manual handling the life cycle. The following is a simple example to illustrate how to use LiveData and show its relationship with the Android life cycle.Suppose we have an activity containing a counter, and I hope to update the UI when the value of the counter changes. First, we need to define a LiveData object to hold the value of the counter.We can create a class named Counterlivedata, inherited from MutableLivedata <Integer>: public class CounterLiveData extends MutableLiveData<Integer> { private int counter = 0; public void increment() { counter++; setValue(counter); } public void decrement() { counter--; setValue(counter); } } The Counterlivedata class is inherited from MutableLivedata, a specific sub -class of LiveData.We define a private Counter variable, and change the value of the counter through the increment () and decrement () methods, and update the new value through the SetValue () method to the LiveData. Next, we need to observe the change of LiveData during the event and update the UI.We can create an observer through the oncreate () method of the activity and update the UI in the onChanged () method. public class MainActivity extends AppCompatActivity { private TextView counterTextView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); CounterLiveData counterLiveData = new CounterLiveData(); counterTextView = findViewById(R.id.counterTextView); counterLiveData.observe(this, new Observer<Integer>() { @Override public void onChanged(Integer counter) { counterTextView.setText(String.valueOf(counter)); } }); } } In this example, we created an object of the counterlivedata and bind the observer to the activity through the Observe () method.In the onChanged () method of the observer, we update the new value of the counter to the UI. Since LiveData can perceive the life cycle, it will only inform the observer when the activity is in the Started or Resumed state where the life cycle is in the Started or Resumed state.This means that when the activity is not visible or destroyed, the onChanged () method will not be triggered, which effectively avoids memory leakage and empty pointer abnormalities. The above is the correlation between Livedata in the Android life cycle and some use examples.With LiveData, we can handle the synchronization of data and UI more concisely and avoid common issues related to life cycle.I hope this article can help you better understand the usage and advantages of LiveData.