How to call a public void to run automatically when my app iniciates
<p>I need to call the following public void automatically as soon as the app gets open:</p>

<pre><code>public void GetIMEI(){
    String deviceId = Settings.Secure.getString(getApplicationContext().getContentResolver(), Settings.Secure.ANDROID_ID);
    Toast.makeText(MainActivity.this, "IMEI: " + deviceId, Toast.LENGTH_SHORT).show();
}
</code></pre>

<p>How can I do that?</p>

<p>Update: This is the main activity of my app</p>

<p>MainActivity.JAVA:</p>

<pre><code>package ar.com.reservo.reservo;

//here go all the imports

public class MainActivity extends Activity {

/* URL saved to be loaded after fb login */
private static final String target_url="http://chapatelo.hol.es/";
private static final String target_url_prefix="chapatelo.hol.es";
private Context mContext;
private WebView mWebview;
private WebView mWebviewPop;
private RelativeLayout mContainer;
private long mLastBackPressTime = 0;
private Toast mToast;
private ValueCallback&lt;Uri&gt; mUploadMessage;
private final static int FILECHOOSER_RESULTCODE=1;

@Override
protected void onActivityResult(int requestCode, int resultCode,
                                Intent intent) {
    if(requestCode==FILECHOOSER_RESULTCODE)
    {
        if (null == mUploadMessage) return;
        Uri result = intent == null || resultCode != RESULT_OK ? null
                : intent.getData();
        mUploadMessage.onReceiveValue(result);
        mUploadMessage = null;
    }
}


@Override
protected void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    // final View controlsView =
    // findViewById(R.id.fullscreen_content_controls);
    CookieManager cookieManager = CookieManager.getInstance();
    cookieManager.setAcceptCookie(true);
    mWebview = (WebView) findViewById(R.id.activity_main_webview);
    //mWebviewPop = (WebView) findViewById(R.id.webviewPop);
    mContainer = (RelativeLayout) findViewById(R.id.webview_relative);
    WebSettings webSettings = mWebview.getSettings();
    webSettings.setJavaScriptEnabled(true);
    webSettings.setAppCacheEnabled(true);
    webSettings.setJavaScriptCanOpenWindowsAutomatically(true);
    webSettings.setAllowUniversalAccessFromFileURLs(true);
    webSettings.setSupportMultipleWindows(true);
    mWebview.setVerticalScrollBarEnabled(true);
    InputMethodManager imm = (InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE);
    imm.hideSoftInputFromWindow(mWebview.getWindowToken(), 0);

    mWebview.setWebViewClient(new UriWebViewClient(){
        @Override
        public void onPageFinished(WebView view, String url) {
            findViewById(R.id.splashLoading1).setVisibility(View.GONE);
            findViewById(R.id.activity_main_webview).setVisibility(View.VISIBLE);
        }
    });

    mWebview.setWebChromeClient(new UriChromeClient(){

        // For Android 3.0+
        public void openFileChooser(ValueCallback&lt;Uri&gt; uploadMsg) {
            mUploadMessage = uploadMsg;
            Intent i = new Intent(Intent.ACTION_GET_CONTENT);
            i.addCategory(Intent.CATEGORY_OPENABLE);
            i.setType("image/*");
            MainActivity.this.startActivityForResult(Intent.createChooser(i,"File Chooser"), FILECHOOSER_RESULTCODE);

        }

        // For Android 3.0+
        public void openFileChooser( ValueCallback uploadMsg, String acceptType ) {
            mUploadMessage = uploadMsg;
            Intent i = new Intent(Intent.ACTION_GET_CONTENT);
            i.addCategory(Intent.CATEGORY_OPENABLE);
            i.setType("*/*");
            MainActivity.this.startActivityForResult(
                    Intent.createChooser(i, "File Browser"),
                    FILECHOOSER_RESULTCODE);
        }

        //For Android 4.1
        public void openFileChooser(ValueCallback&lt;Uri&gt; uploadMsg, String acceptType, String capture){
            mUploadMessage = uploadMsg;
            Intent i = new Intent(Intent.ACTION_GET_CONTENT);
            i.addCategory(Intent.CATEGORY_OPENABLE);
            i.setType("image/*");
            MainActivity.this.startActivityForResult( Intent.createChooser( i, "File Chooser" ), MainActivity.FILECHOOSER_RESULTCODE );

        }
    });
    mWebview.loadUrl(target_url);

    mContext=this.getApplicationContext();
}


private class UriWebViewClient extends WebViewClient{
    @Override
    public boolean shouldOverrideUrlLoading(WebView view, String url) {
        String host = Uri.parse(url).getHost();
        //Log.d("shouldOverrideUrlLoading", url);
        if (host.equals(target_url_prefix))
        {
            // This is my web site, so do not override; let my WebView load
            // the page
            if(mWebviewPop!=null){
                mWebviewPop.setVisibility(View.GONE);
                mContainer.removeView(mWebviewPop);
                mWebviewPop=null;
            }
            return false;
        }

        if(host.equals("m.facebook.com") || host.equals("www.facebook.com")){
            return false;
        }
        // Otherwise, the link is not for a page on my site, so launch
        // another Activity that handles URLs
        Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
        startActivity(intent);
        return true;
    }

    @Override
    public void onReceivedSslError(WebView view, SslErrorHandler handler,
                                   SslError error) {
        Log.d("onReceivedSslError", "onReceivedSslError");
        //super.onReceivedSslError(view, handler, error);
    }
}

class UriChromeClient extends WebChromeClient {

    @Override
    public boolean onCreateWindow(WebView view, boolean isDialog,
                                  boolean isUserGesture, Message resultMsg) {
        mWebviewPop = new WebView(mContext);
        mWebviewPop.setVerticalScrollBarEnabled(false);
        mWebviewPop.setHorizontalScrollBarEnabled(false);
        mWebviewPop.setWebViewClient(new UriWebViewClient());
        mWebviewPop.getSettings().setJavaScriptEnabled(true);
        mWebviewPop.getSettings().setSavePassword(false);
        mWebviewPop.setLayoutParams(new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
                ViewGroup.LayoutParams.MATCH_PARENT));
        mContainer.addView(mWebviewPop);
        WebView.WebViewTransport transport = (WebView.WebViewTransport) resultMsg.obj;
        transport.setWebView(mWebviewPop);
        resultMsg.sendToTarget();

        return true;
    }

    @Override
    public void onCloseWindow(WebView window) {
        Log.d("onCloseWindow", "called");
    }
}

@Override
public void onConfigurationChanged(Configuration newConfig){
    super.onConfigurationChanged(newConfig);
}


public void GetIMEI(){
   String deviceId = Settings.Secure.getString(getApplicationContext().getContentResolver(), Settings.Secure.ANDROID_ID);
   Toast.makeText(MainActivity.this, "IMEI: " + deviceId, Toast.LENGTH_SHORT).show();
}

/*@Override
public boolean onKeyDown(int keyCode, KeyEvent event){

    if(keyCode == KeyEvent.KEYCODE_BACK){
        mWebview.loadUrl("javascript:()");
    }

    return super.onKeyDown(keyCode, event);
}*/


@Override
public void onBackPressed(){
   /* if(mWebview.canGoBack()){
        mWebview.goBack();
    }else{
        Toast.makeText(MainActivity.this, "Has salido de 'Contacto'", Toast.LENGTH_SHORT).show();
        super.onBackPressed();
    }*/
    Toast.makeText(MainActivity.this, "Saliste de 'Chapátelo'. ¡Nos vemos la próxima vez!", Toast.LENGTH_SHORT).show();
    super.onBackPressed();
}
}
</code></pre>

<p>I hope it is enough information to make clear how my code is and to help you find out how to call that public void specifically for my case.</p>