Recently, I upgraded my android studio to 4.2.1. Then I found all of my projects are not working, I got this erro rnavigation.json (The system cannot find the path specified). Even I created a blank activity project, I got the same error. Therefore, somethings. I tried to switch to lower sdk version, that is still not working. Finally, I found out I put my project in an external disk which is using ex3 format. So that, I can use it in my pc and mac. Is the disk format causing problems? Then I moved my project to the main disk which is using NTFS. Then that is no problems, strange

As I remember, when I copied a service class from my previous system. But I got this error striaght away: can't resolve all parameters for InvoiceService: (?). I checked it should be in module class, imported the modules I need for the constructor. Finally, I found in Angular 8, that required @Injectable at the top of class. A silly mistake...

These few months, I am working on a project which is using Angular Material Framework. Its functions are very rich. It makes UI very nice. But you need to have a very tiny html template. I found my Radio Button is not working. You cannot select the values. After several trial and error, I found the mistakes I did is placing mat-radio-group elements in a mat-form-field element. Even the page is still rendering the nice UI, but the functions are not working. The solution is simple, I just need to change mat-form-field to a div!

Angular Material framework is very useful. It will make your SPA look like a native mobile app. It works fine in desktop, tablet and Mobile. However, I found sometimes, the styles are broken and the Animations does not working anymore. I did a research on the internet, a lot of people are saying that is because the style files are not applied. In my situation, it does not sounds that is the case. Finally, I deleted the elements one by one. Then I found it caused by the malform elements

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In the past, AngularJS is using "ng-if" to control whether the div is show or hide. That is basic 101. In Angular, the syntax are changed, there are no more "ng-" somethings. Now, that is using somethings more similar with, [hidden]. So you can bind a variable with that to control the visibility of div.
Example:

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