How to enable cookies in android webview?

CookieManager.getInstance() is the CookieManager instance for your entire application. Hence, you enable or disable cookies for all the webviews in your application.

Normally it should work if your webview is already initialized: http://developer.android.com/reference/android/webkit/CookieManager.html#getInstance()

Maybe you call CookieManager.getInstance().setAcceptCookie(true); before you initialize your webview and this is the problem?

You should consider that

CookieManager.getInstance().setAcceptCookie(true);

doesn't work from lollipop(API21) and above. You should check and use appropriate function for that case:

if (android.os.Build.VERSION.SDK_INT >= 21) {   
     CookieManager.getInstance().setAcceptThirdPartyCookies(mWebView, true);
} else {
     CookieManager.getInstance().setAcceptCookie(true);
}