WebViewActivity.kt

package me.undownding.common

import android.annotation.SuppressLint
import android.os.Bundle
import android.support.v7.app.AppCompatActivity
import android.view.MenuItem
import android.webkit.WebView
import android.webkit.WebViewClient

class WebViewActivity: AppCompatActivity() {

    private val webView by lazy { WebView(this) }

    @SuppressLint("SetJavaScriptEnabled")
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(webView)
        supportActionBar?.setDisplayHomeAsUpEnabled(true)

        with(webView.settings) {
            javaScriptEnabled = true
            domStorageEnabled = true
            databaseEnabled = true
        }

        webView.webViewClient = object : WebViewClient() {

            override fun shouldOverrideUrlLoading(view: WebView?, url: String?): Boolean {
                view?.loadUrl(url)
                return true
            }

            override fun onPageFinished(view: WebView?, url: String?) {
                supportActionBar?.title = view?.title
            }

        }

        webView.loadUrl(intent.dataString)
    }

    override fun onOptionsItemSelected(item: MenuItem?): Boolean = when(item?.itemId) {
        android.R.id.home -> {
            onBackPressed()
            true
        }
        else -> {
            super.onOptionsItemSelected(item)
        }
    }

    override fun onBackPressed() {
        if (webView.canGoBack()) {
            webView.goBack()
        } else {
            finish()
        }
    }
}