使用Android数据绑定动态切换布局元素的可见性.

我正在构建一个Android应用程序,我想根据按钮点击切换一些视图元素的可见性.我试图用数据绑定而不是使用findViewById()来存档它,但是直到现在我发现的所有解决方案都不会在更改变量时更新布局.

这是我到目前为止所拥有的. (我简化了代码,专注于问题)

Activicy.java

public class RecipeActivity extends AppCompatActivity {
private Recipe recipe;
private ActivityRecipeBinding binding;
private RecipeBinderHelper rbhelper = new RecipeBinderHelper();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Intent intent = getIntent();
    recipe = intent.getParcelableExtra("recipe");
    binding = DataBindingUtil.setContentView(this,R.layout.activity_recipe);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    toolbar.setTitle(recipe.getName());
    setSupportActionBar(toolbar);
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);

    binding.recipeContent.setRecipe(recipe);
    binding.recipeContent.setHelper(rbhelper);

    binding.Button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            //HERE I CHANGE THE VALUE OF THE VARIBLE
            rbhelper.setPresentationViewVisible(false);
            binding.notifyChange();
        }
    });
}
}

助手班

public class RecipeBinderHelper{
private Boolean presentationElementsVisible;
private Boolean timerElementsVisible;

public RecipeBinderHelper(){
    this.presentationElementsVisible = true;
    this.timerElementsVisible = false;
}
public void setPresentationViewVisible(boolean presentationElementsVisible) {
    this.presentationElementsVisible = presentationElementsVisible;
}
public Boolean getPresentationElementsVisible() {
    return presentationElementsVisible;
}
//getters and setters for private Boolean timerElementsVisible;
}

布局

最佳答案

我强烈推荐阅读George Mount的posts about Android data-binding,它们非常实用.

为解决这个问题,我将助手类扩展为BaseObservable,如the documentation所述.

助手班

public class RecipeBinderHelper{
    private Boolean presentationElementsVisible;
    private Boolean timerElementsVisible;

    public RecipeBinderHelper(){
        this.presentationElementsVisible = true;
        this.timerElementsVisible = false;
    }
    public void setPresentationViewVisible(boolean presentationElementsVisible) {
        this.presentationElementsVisible = presentationElementsVisible;
        //Notifying change in the setter. 
        notifyPropertyChanged(BR.presentationElementsVisible);
    }
    //assigning Bindable annotation to the getter 
    @Bindable
    public Boolean getPresentationElementsVisible() {
        return presentationElementsVisible;
    }
    //getters and setters for private Boolean timerElementsVisible;
}

Activity中的binding.notifyChange();不是必需的,可以删除.

现在,当单击按钮时,应用程序会根据需要删除TextView.

一个奇怪的事情是Android Studio(2.1.2,Ubuntu)给了我一个无法解决符号’BR’警告,但应用程序编译并按预期运行.