让我先从展示代码开始:

build.gradle(模块):

android {
compileSdkVersion 24
buildToolsVersion "24.0.2"
dataBinding {
    enabled = true
}
defaultConfig {
    applicationId "com.example.oryaa.basecalculator"
    minSdkVersion 15
    targetSdkVersion 24
    versionCode 1
    versionName "1.0"
}
buildTypes {
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }
}


dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
testCompile 'junit:junit:4.12'
compile 'com.android.support:appcompat-v7:24.2.1'
compile 'com.google.android.gms:play-services-appindexing:8.1.0'

activity_main.xml:

<data>
    <import type="android.view.View" />
    <variable
        name="baseCalcModel"
        type="com.example.oryaa.basecalculator.BaseCalcModel">
    </variable>
</data>  <TextView
        android:id="@+id/resultOutput"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/resultTextView"
        android:textColor="@color/DarkBlue"
        android:text="@{baseCalcModel.calcResult}"
        android:textSize="32dp" />

MainActivity.java:

public class MainActivity extends AppCompatActivity {

EditText userInput = null;
TextView resultTV = null;
Spinner fromBaseSpinner = null;
Spinner toBaseSpinner = null;
ArrayList<String> spinnerArray = new ArrayList<>();
String _allowedChars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
String _onlyOnceChar = "-+*/";
BaseCalcModel baseCalcModel = new BaseCalcModel();

/**
 * ATTENTION: This was auto-generated to implement the App Indexing API.
 * See https://g.co/AppIndexing/AndroidStudio for more information.
 */
private GoogleApiClient client;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    ActivityMainBinding binding = DataBindingUtil.setContentView(this, R.layout.activity_main);
    binding.setBaseCalcModel(this.baseCalcModel);
    this.resultTV = (TextView) this.findViewById(R.id.resultOutput);
    this.fromBaseSpinner = (Spinner) findViewById(R.id.fromBaseSpinner);
    this.toBaseSpinner = (Spinner) findViewById(R.id.toBaseSpinner);
    this.userInput = (EditText) findViewById(R.id.userInput);
    SetupUI();
    baseCalcModel.setCalcResult("test");

    // ATTENTION: This was auto-generated to implement the App Indexing API.
    // See https://g.co/AppIndexing/AndroidStudio for more information.
    client = new GoogleApiClient.Builder(this).addApi(AppIndex.API).build();
}

基础计算模型.java:

ublic class BaseCalcModel extends BaseObservable {


public String calcResult;
public BaseView firstNumView;
public BaseView secondNumView;
public BaseView resultNumView;
public int firstNumBase;
public int secondNumBase;
public int resultNumBase;
public String error;


@Bindable
String getCalcResult() {
    return calcResult;
}

@Bindable
public BaseView getFirstNumView() {
    return firstNumView;
}

@Bindable
public BaseView getSecondNumView() {
    return secondNumView;
}

@Bindable
public BaseView getResultNumView() {
    return this.resultNumView;
}

@Bindable
public int getFirstNumBase() {
    return this.firstNumBase;
}

@Bindable
public int getSecondNumBase() {
    return this.secondNumBase;
}

@Bindable
public int getResultNumBase() {
    return this.resultNumBase;
}

@Bindable
public String getError() {
    return this.error;
}

public void setCalcResult(String calcResult) {
    this.calcResult = calcResult;
    notifyPropertyChanged(com.example.oryaa.basecalculator.BR.calcResult);
}

public void setFirstNumView(BaseView firstNumView) {
    this.firstNumView = firstNumView;
    notifyPropertyChanged(com.example.oryaa.basecalculator.BR.firstNumView);
}

public void setSecondNumView(BaseView secondNumView) {
    this.secondNumView = secondNumView;
    notifyPropertyChanged(com.example.oryaa.basecalculator.BR.secondNumView);
}

public void setResultNumView(BaseView resultNumView) {
    this.resultNumView = resultNumView;
    notifyPropertyChanged(com.example.oryaa.basecalculator.BR.resultNumView);
}

public void setFirstNumBase(int firstNumBase) {
    this.firstNumBase = firstNumBase;
    notifyPropertyChanged(com.example.oryaa.basecalculator.BR.firstNumBase);
}

public void setSecondNumBase(int secondNumBase) {
    this.secondNumBase = secondNumBase;
    notifyPropertyChanged(com.example.oryaa.basecalculator.BR.secondNumBase);
}

public void setResultNumBase(int resultNumBase) {
    this.resultNumBase = resultNumBase;
    notifyPropertyChanged(com.example.oryaa.basecalculator.BR.resultNumBase);
}

public void setError(String error) {
    this.error = error;
    notifyPropertyChanged(com.example.oryaa.basecalculator.BR.error);
}


public BaseCalcModel() {
    firstNumView = new BaseView();
    secondNumView = new BaseView();
    resultNumView = new BaseView();
    firstNumBase = 0;
    secondNumBase = 0;
    resultNumBase = 0;
    calcResult = "";
    error = "";
}

public BaseCalcModel(BaseView firstNumView, BaseView secondNumView, BaseView resultNumView,
                     int firstNumBase, int secondNumBase, int resultNumBase, String clcResult,
                     String error) {
    this.firstNumView = firstNumView;
    this.secondNumView = secondNumView;
    this.resultNumView = resultNumView;
    this.firstNumBase = firstNumBase;
    this.secondNumBase = secondNumBase;
    this.resultNumBase = resultNumBase;
    this.calcResult = clcResult;
    this.error = error;
}

我正在尝试进行简单的数据绑定(bind)，但在 proparty 更改后我的 View 没有更新。 正如您在图片中看到的，我的代码到达:

            notifyPropertyChanged(com.example.oryaa.basecalculator.BR.calcResult);

但 View 仅在应用程序启动时或在我将手机从垂直方向旋转到水平方向或从垂直方向旋转到水平方向时才会更新。

我的问题在哪里？

非常感谢， 或者雅科夫

最佳答案

如果您在使用 LiveData 时遇到此问题，您可能忘记了设置绑定(bind)的生命周期所有者； binding.setLifecycleOwner(lifecycleOwner)

关于java - Android 数据绑定(bind) : view does not update when property is changed，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/41913818/