android databinding using "&&" logical operator

Question

I am trying to use the and "&&" operator in xml using Android databinding,

android:visibility="@{(bean.currentSpaceId == bean.selectedSpaceId **&&** bean.currentSpaceId > 0)? View.VISIBLE: View.GONE}"

but I got the compilation error:

Error:Execution failed for task ':app:dataBindingProcessLayoutsDevDebug'. org.xml.sax.SAXParseException; systemId: file:/Users/path/app/build/intermediates/res/merged/dev/debug/layout/fragment_space.xml; lineNumber: 106; columnNumber: 89; The entity name must immediately follow the '&' in the entity reference.

and red highlight error in android studio "unescaped & or non terminated character".

So how should I fix this?

Edit: found the answer, these character needs to be escaped:

'&' --> '&'

'<' --> '&lt;'

'>' --> '&gt;'

Answer 1

List of HTML entities

You can not use & or some other HTML entity in XML. So you have to use escaping character.

android:text="@{(1==1 && 2>0) ? `true` : `false`}"

HTML Character entities often used in Android:

+--------+----------------------------+--+--+--+
| Symbol | Equivalent HTML Entity     |  |  |  |
+--------+----------------------------+--+--+--+
| >      | >                       |  |  |  |
+--------+----------------------------+--+--+--+
| <      | &lt;                       |  |  |  |
+--------+----------------------------+--+--+--+
| "      | &quot;, &ldquo; or &rdquo; |  |  |  |
+--------+----------------------------+--+--+--+
| '      | &apos;, &lsquo; or &rsquo; |  |  |  |
+--------+----------------------------+--+--+--+
| }      | &#125;                     |  |  |  |
+--------+----------------------------+--+--+--+
| &      | &amp;                      |  |  |  |
+--------+----------------------------+--+--+--+
| space  | &#160;                     |  |  |  |
+--------+----------------------------+--+--+--+

Here is a complete list of HTML entities.

Answer 2

Escaping && in the layout mark-up is a very poor solution. It is better to create a method on the (view)model object:

android:visibility="@{user.adult ? View.VISIBLE : View.GONE}"

public boolean isAdult() {
    return age >= 18;
}

Answer 3

The best solution that I could come up with for this problem was introducing a new Bindable method.

Before:

item_recyclerview.xml:

<EditText
...
android:enabled="@{myViewModel.myDataModelClass.lastAddedItem &amp;&amp; !myViewModel.myDataModelClass.editTextDisabled}"
/>

MyDataModelClass: (which is being held in my viewmodel)

...
private boolean lastAddedItem;
private boolean editTextDisabled;
...
@Bindable
public boolean isLastAddedItem() {
    return lastAddedItem;
}
public void setLastAddedItem(boolean lastAddedItem) {
    this.lastAddeditem = lastAddedItem;
    notifyPropertyChanged(BR.lastAddedItem);
}
@Bindable
public boolean isEditTextDisabled() {
    return editTextDisabled;
}
public void setEditTextDisabled(boolean editTextDisabled) {
    this.editTextDisabled = editTextDisabled;
    notifyPropertyChanged(BR.editTextDisabled);
}

After:

item_recyclerview.xml:

<EditText
...
android:enabled="@{myViewModel.myDataModelClass.enableEditing}"
/>

MyDataModelClass: (which is being held in my viewmodel)

...
private boolean lastAddedItem;
private boolean editTextDisabled;
...
@Bindable
public boolean isLastAddedItem() {
    return lastAddedItem;
}
public void setLastAddedItem(boolean lastAddedItem) {
    this.lastAddeditem = lastAddedItem;
    notifyPropertyChanged(BR.lastAddedItem);
    notifyPropertyChanged(BR.isEnableEditing);
}
@Bindable
public boolean isEditTextDisabled() {
    return editTextDisabled;
}
public void setEditTextDisabled(boolean editTextDisabled) {
    this.editTextDisabled = editTextDisabled;
    notifyPropertyChanged(BR.editTextDisabled);
    notifyPropertyChanged(BR.isEnableEditing);
}
@Bindable
public boolean isEnableEditing() {
    return isLastAddedItem() && !isEditTextDisabled();
}

Answer 4

Try 'compareTo' method in the XML like

android:visibility=${viewModel.intValue.compareTo(0) == -1 ? View.GONE : View.VISIBLE}"