Why does Android Studio not deploy my latest changes to my device when I run my project?

Question

Note:This question is not about how to fix a NullPointerException. This question is about why a piece of code that has been updated still generates a stacktrace in the Android Studio application for an older version.

I have a class that checks internet connectivity. This class, however, used to have an invalid piece of code, like this:

public class InternetConnectivityChecker {
    private Context context;

    public InternetConnectivityChecker(Context context) {
        context = context;
    }

I fixed this piece of code by changing it to:

public class InternetConnectivityChecker {
    private Context context;

    public InternetConnectivityChecker(Context context) {
        this.context = context;
    }

I kept getting a stacktrace, pasted below. To fix that, I decided to remove the invokation of the class altogether.

This class used to be called from SamaWebViewClient, on line 22. However, now it is not being called anymore:

public class SamaWebViewClient extends WebViewClient {
    private com.sama7.sama.listeners.OnReceivedErrorListener onReceivedErrorListener;

    public SamaWebViewClient(com.sama7.sama.listeners.OnReceivedErrorListener listener) {
        this.onReceivedErrorListener = listener;
    }

    @Override
    public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {
            onReceivedErrorListener.onReceivedError();
    }

}

However, now when I run my code in debug mode, even though I get 0 errors and 0 warnings in the Gradle Build window, this is what I see in logcat:

03-02 08:49:29.240 24373-24373/com.sama7.sama E/AndroidRuntime: FATAL EXCEPTION: main
                                                            Process: com.sama7.sama, PID: 24373
                                                                java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object android.content.Context.getSystemService(java.lang.String)' on a null object reference
                                                                at com.sama7.sama.InternetConnectivityChecker.isConnected(InternetConnectivityChecker.java:15)
                                                                at com.sama7.sama.SamaWebViewClient.onReceivedError(SamaWebViewClient.java:22)
                                                                at com.android.webview.chromium.WebViewContentsClientAdapter.onReceivedError(WebViewContentsClientAdapter.java:582)
                                                                at org.chromium.android_webview.AwContentsClient.onReceivedError(AwContentsClient.java:355)
                                                                at org.chromium.android_webview.AwContentsClientCallbackHelper$MyHandler.handleMessage(AwContentsClientCallbackHelper.java:160)
                                                                at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                at android.os.Looper.loop(Looper.java:145)
                                                                at android.app.ActivityThread.main(ActivityThread.java:5832)
                                                                at          java.lang.reflect.Method.invoke(Native Method)
                                                                at     java.lang.reflect.Method.invoke(Method.java:372)
                                                                at     com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399)
                                                                at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)
03-02 08:49:38.015 24373-24373/com.sama7.sama I/Process: Sending signal. PID: 24373 SIG: 9

Why am I not getting the latest application built and deployed to my Samsung Galaxy S5 device?

Answer 1

For anyone discovering this in the future, here is what worked for me.

Turning Instant Run Off

If you need to turn off Instant Run, go to Settings → Build, Execution, Deployment → Instant Run and uncheck Enable Instant Run… .

This is an excerpt from the Android tools page on instant run.