Android: ViewModel+LiveData+Data

EditText实现双向绑定

配置: 模块build中设置使用DataBinding

defaultConfig {
        ...
        dataBinding{
            enabled true
        }
    }

Activity

//设置contentView 返回值是ViewBinding对象
ALoginBinding dataBinding = DataBindingUtil.setContentView(this, R.layout.a_login);
EmergencyContactViewModel viewModel = new ViewModelProvider(this).get(EmergencyContactViewModel.class);
dataBinding.setViewModel(viewModel);
dataBinding.setLifecycleOwner(this);

dataBinding.setViewModel(viewModel);
dataBinding.setLifecycleOwner(this);
注意此处要记得databinding和Viewmodel进行绑定

然后来到我们需要支持Databinding的xml布局文件中
将光标定位在 最开始
然后按下Alt+Enter键

image.png
可快捷生成DataBinding代码

<?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:etApp="http://schemas.android.com/tools">

    <data>
        <variable
            name="viewModel"
            type="com.ceshi.LoginViewModel" />
    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">
                <EditText
                    android:id="@+id/et_phoneNumber"
                    android:layout_width="match_parent"
                    android:layout_height="42dp"
                    app:layout_constraintLeft_toLeftOf="parent"
                    app:layout_constraintRight_toRightOf="parent"
                    android:inputType="phone"
                    android:afterTextChanged="@{(editable) -> viewModel.setPhoneNumber(editable.toString())}"
                    android:text="@{viewModel.phoneNumber}"
                    android:textSize="15sp"
                    android:textColor="@color/title_333" />
    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

主要是这两句

android:afterTextChanged="@{(editable) -> viewModel.setPhoneNumber(editable.toString())}"
android:text="@{viewModel.phoneNumber}"

ViewModel类

public class LoginViewModel extends ViewModel {
    private MutableLiveData<String> phoneNumber;
    public LoginViewModel() {
        phoneNumber = new MutableLiveData<>();
    }
  public void setPhoneNumber(String phoneNumber1) {
        this.phoneNumber.setValue(phoneNumber1);
    }
}