Encountering an issue in Android Studio 1.3.1 when trying to create a SQLite

I encountered an error on line 26 of MainActivity.java. A Java NULLPOINTER Exception is being displayed. Can someone please advise me on how to resolve this issue? My code is available on GitHub. https://github.com/happyshravan/SQLite

Latest LogCat error:

2-25 21:10:58.729  15661-15661/abcd.shravankr.sqlite D/memalloc﹕ /dev/pmemMapped buffer base:0x530b2000 size:10047488 offset:8511488 fd:66
12-25 21:11:06.679  15661-15661/abcd.shravankr.sqlite D/AndroidRuntime﹕ Shutting down VM
12-25 21:11:06.679  15661-15661/abcd.shravankr.sqlite W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x40c15a68)
12-25 21:11:06.699  15661-15661/abcd.shravankr.sqlite E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.IllegalStateException: Could not execute method for android:onClick
        at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:275)
        at android.view.View.performClick(View.java:3571)
        at android.view.View$PerformClick.run(View.java:14247)
        at android.os.Handler.handleCallback(Handler.java:605)
        at android.os.Handler.dispatchMessage(Handler.java:92)
        at android.os.Looper.loop(Looper.java:137)
        at android.app.ActivityThread.main(ActivityThread.java:4517)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:993)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:760)
        at dalvik.system.NativeStart.main(Native Method)
 Caused by: java.lang.reflect.InvocationTargetException
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at
javascriptc#android

Answer №1

I encountered an issue on line 26 of MainActivity.java

Line 26 pertains to the method 

public void addButtonClicked(View view)

In your XML file, you have defined two buttons with ids addButton and deleteButton, but it seems like they are not being utilized in MainActivity.

A Java NullPointerException is being thrown

This is because you are trying to use these buttons without initializing them first.

Solution :

Try adding this code inside the onCreate method:

Button addBtn=(Button)findViewById(R.id.addButton);
Button deleteBtn=(Button)findViewById(R.id.deleteButton);

Edited

Remove 

android:onClick="addButtonClicked"
and 
android:onClick="deleteButtonClicked"
from the main_activity XML file, and remove addButtonClicked and deleteButtonClicked methods from MainActivity. Replace them with the following code.

MainActivity

 addBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) { //   add button is clicked
            Toast.makeText(getApplicationContext(),"Shravan",Toast.LENGTH_LONG).show();
            Products product = new Products(shravansInput.getText().toString());
            dbHandler.addProduct(product);
            printDatabase();
            }
        });


  deleteBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) { //   delete button is clicked
            String inputText=shravansInput.getText().toString();
            dbHandler.deleteProduct(inputText);
            printDatabase();
        });

Place this code inside the onCreate method.

I believe implementing these changes will resolve the issue.

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