Android Back Arrow on Toolbar (AppCompatActivity)

Question

I want to show the back arrow button in my app, but the app crashes when I put this in my code:

getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setDisplayShowHomeEnabled(true);

style.xml

 <style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
    <item name="colorPrimary">@color/PrimaryColor</item>
    <item name="colorPrimaryDark">@color/PrimaryColorDark</item>
    <item name="colorAccent">@color/PrimaryColor</item>
    <item name="colorControlHighlight">@color/ControlHighlight</item>
    <item name="android:statusBarColor" tools:targetApi="21">@android:color/transparent</item>
</style>


<style name="ActionBarPopupThemeOverlay" parent="ThemeOverlay.AppCompat.Light" >
    <item name="android:textColor">#000000</item>
</style>


<style name="MyCustomTabLayout" parent="Widget.Design.TabLayout">
    <item name="tabIndicatorColor">#FFFFFF</item>
    <item name="tabIndicatorHeight">3dp</item>
    <item name="tabTextAppearance">@style/MyCustomTabTextAppearance</item>
</style>


<style name="MyCustomTabTextAppearance" parent="TextAppearance.Design.Tab">
    <item name="android:textColor">#FFFFFF</item>
</style>

toolbar.xml

<android.support.v7.widget.Toolbar xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_height="@dimen/abc_action_bar_default_height_material"
android:elevation="0dp"
android:layout_width="match_parent"
android:id="@+id/toolbar"
android:background="@color/PrimaryColor"
app:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
app:popupTheme="@style/ActionBarPopupThemeOverlay"/>

Class (not Fragment):

public class WebViewCanale extends AppCompatActivity {

    Toolbar toolbar;
    TextView textView;
    WebView webView;
    ProgressBar progressBar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.webview_canali);

        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setDisplayShowHomeEnabled(true);

        //Toolbar
        toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);


        //FindViewById
        webView = (WebView) findViewById(R.id.webview);
        textView = (TextView) findViewById(R.id.textView);
        progressBar = (ProgressBar) findViewById(R.id.progressBar);

        //Impostazioni WebView
        WebSettings webSettings = webView.getSettings();
        webSettings.setJavaScriptEnabled(true);
        webSettings.setLoadsImagesAutomatically(true);
        webView.loadUrl(this.getIntent().getDataString());
        webView.getSettings().setCacheMode(WebSettings.LOAD_NO_CACHE);
        webView.getSettings().setAppCacheEnabled(false);

        //Titolo Toolbar
        webView.setWebChromeClient(new WebChromeClient() {
            @Override
            public void onReceivedTitle(WebView view, String title) {
                super.onReceivedTitle(view, title);
                if (!TextUtils.isEmpty(title)) {
                    WebViewCanale.this.setTitle(title);
                }
            }
        });
    }
}

Answer 1

You can also just declare in the Manifest a ParentActivity with: <activity android:name=".ThisActivity" android:parentActivityName=".TheActivityThatCalledThisOne"> </activity>