[Vuejs]-Need help initialized Vuetify into my vue-cli 3

In main.js changed

import './plugins/vuetify'

to

import vuetify from './plugins/vuetify'**

and then add it into new Vue instance like this:

new Vue({
...
  vuetify,
...
}).$mount('#app')

for example, main.js:

    import Vue from 'vue'
    import App from './App.vue'
    import router from './router'
    import store from './store'
    import vuetify from './plugins/vuetify'
    import 'material-design-icons-iconfont/dist/material-design-icons.css'
    Vue.config.productionTip = false
    new Vue({
      router,
      store,
      vuetify,
      render: h => h(App)
    }).$mount('#app')

and vuetify.js:

    import Vue from 'vue'
    import Vuetify from 'vuetify'
    import 'vuetify/dist/vuetify.min.css'
    import colors from 'vuetify/es5/util/colors'

    Vue.use(Vuetify)

    export default new Vuetify({
      iconfont: 'md',
      theme: {
        primary: colors.green.darken1,
        secondary: colors.green.lighten4,
        accent: colors.green.darken3
      }
    })