private MutableLiveData<Integer> number;public MutableLiveData<Integer> getNumber() {if (number == null) {number = new MutableLiveData<>();number.setValue(0);}return number;}public void changednumber(Int newnumber) {number.setValue(number.getValue()+newnumber);}

private val _number:MutableLiveData<Int> by lazy { MutableLiveData<Int>(0) }//初始值为0var number=_numberfun changednumber(a:Int){_number.value= _number.value?.plus(a)}

<data><variablename="vm"type="com.example.mutablelivedata.MyViewModel" /></data>android:text="@{String.valueOf(vm.number)}"android:onClick="@{()->vm.changednumber(5)}"android:progress="@{vm.number}"

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:app="http://schemas.android.com/apk/res-auto"xmlns:tools="http://schemas.android.com/tools"><data><variablename="vm"type="com.example.kotlinmutablelivedata.MyViewModel" /></data><androidx.constraintlayout.widget.ConstraintLayoutandroid:layout_width="match_parent"android:layout_height="match_parent"tools:context=".MainActivity"><TextViewandroid:id="@+id/textone"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="@{String.valueOf(vm.number)}"android:textSize="30sp"app:layout_constraintBottom_toBottomOf="parent"app:layout_constraintLeft_toLeftOf="parent"app:layout_constraintRight_toRightOf="parent"app:layout_constraintTop_toTopOf="parent" /><Buttonandroid:id="@+id/btn"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="+5"android:onClick="@{()->vm.changednumber(5)}"app:layout_constraintBottom_toBottomOf="parent"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent" /><SeekBarandroid:id="@+id/seekBar"android:progress="@{vm.number}"android:layout_width="0dp"android:layout_height="wrap_content"android:layout_marginBottom="32dp"android:max="15"app:layout_constraintBottom_toTopOf="@+id/textone"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent" /></androidx.constraintlayout.widget.ConstraintLayout>
</layout>

binding = DataBindingUtil.setContentView(this,R.layout.activity_main);myViewModel =new ViewModelProvider(this).get(MyViewModel.class);binding.setVm(myViewModel);binding.setLifecycleOwner(this);

val viewModel = ViewModelProvider(this).get(MyViewModel::class.java)val binding: ActivityMainBinding =DataBindingUtil.setContentView(this, R.layout.activity_main)binding.apply {vm = viewModel //设定对象lifecycleOwner = this@MainActivity //定义被观察者}