reference Tableview is null

[betto2000]

Riepilogo.java
TableView list = findViewById(R.id.List);
String[] headers ={"Articolo","Lotto","Quantità","Utente"};
list.setHeaderAdapter(new SimpleTableHeaderAdapter(this,headers));

activity_main.xml
<de.codecrafters.tableview.TableView
android:id="@+id/List"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:tableView_columnCount="4" />

Error when i create the table
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.gestionelamiere, PID: 26419
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.gestionelamiere/com.example.gestionelamiere.Riepilogo}: java.lang.NullPointerException: Attempt to invoke virtual method 'void de.codecrafters.tableview.TableView.setHeaderAdapter(de.codecrafters.tableview.TableHeaderAdapter)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3271)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3410)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2017)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:214)
at android.app.ActivityThread.main(ActivityThread.java:7397)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:935)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void de.codecrafters.tableview.TableView.setHeaderAdapter(de.codecrafters.tableview.TableHeaderAdapter)' on a null object reference
at com.example.gestionelamiere.Riepilogo.onCreate(Riepilogo.java:32)
at android.app.Activity.performCreate(Activity.java:7825)
at android.app.Activity.performCreate(Activity.java:7814)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1307)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3246)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3410) 
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83) 
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2017) 
at android.os.Handler.dispatchMessage(Handler.java:107) 
at android.os.Looper.loop(Looper.java:214) 
at android.app.ActivityThread.main(ActivityThread.java:7397) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:935)