Is it usefull using WebView whole layout in native Android app?

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http://stackoverflow.com – I am developing an android app. My app have a lot of activities. I want to develop native android app. But in some case, I want to use webview. Layout just have a webview. No linear or relative or another layout. Just webview. All of the images and other things running in HTML.All of screen running HTML5. So, partically I can transfer my app into iphone app or others. This is benefit of this way. But I don't know. Is this way true? What performance will be? What is the disadvantage this way? Can you explain? Regards (HowTos)