How to instance AppCompatActivity in ListView parent?

Question

I am new to android. I use a class that extends ListActivity.

public class ToLines extends ListActivity implements SimpleGestureFilter.SimpleGestureListener{}

But, in this class I want to call a method from AppCompatActivity. So I tried to instance AppCompatActivity class like this:

AppCompatActivity compat = new AppCompatActivity();
            compat.setSupportActionBar(toolbar);
            compat.getSupportActionBar().setDisplayHomeAsUpEnabled(true);

but, the code shows error. This is my logcat:

12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime: FATAL EXCEPTION: main
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime: Process: com.example.fahrudin.sjbapps, PID: 14754
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.fahrudin.sjbapps/com.example.fahrudin.sjbapps.ToLines}: java.lang.NullPointerException
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2429)
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2493)
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at android.app.ActivityThread.access$800(ActivityThread.java:166)
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1283)
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:102)
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:136)
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:5584)
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at java.lang.reflect.Method.invokeNative(Native Method)
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:515)
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1268)
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1084)
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at dalvik.system.NativeStart.main(Native Method)
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:  Caused by: java.lang.NullPointerException
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at android.support.v7.app.AppCompatDelegateImplBase.<init>(AppCompatDelegateImplBase.java:69)
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at android.support.v7.app.AppCompatDelegateImplV7.<init>(AppCompatDelegateImplV7.java:145)
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at android.support.v7.app.AppCompatDelegateImplV11.<init>(AppCompatDelegateImplV11.java:28)
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at android.support.v7.app.AppCompatDelegateImplV14.<init>(AppCompatDelegateImplV14.java:29)
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:135)
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:117)
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at android.support.v7.app.AppCompatActivity.getDelegate(AppCompatActivity.java:456)
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at android.support.v7.app.AppCompatActivity.setSupportActionBar(AppCompatActivity.java:99)
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at com.example.fahrudin.sjbapps.ToLines.onCreate(ToLines.java:86)
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at android.app.Activity.performCreate(Activity.java:5447)
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094)
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2393)
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2493) 
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at android.app.ActivityThread.access$800(ActivityThread.java:166) 
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1283) 
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:102) 
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:136) 
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:5584) 
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at java.lang.reflect.Method.invokeNative(Native Method) 
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:515) 
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1268) 
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1084) 
12-15 12:00:20.923 14754-14754/com.example.fahrudin.sjbapps E/AndroidRuntime:     at dalvik.system.NativeStart.main(Native Method)

What should I do to call AppCompatActivity's method while my class extends ListView?

You never create instance of `Activity`. – Piyush Dec 15 '15 at 05:55 — Piyush, Dec 15 '15 at 05:55

score 1 · Answer 1 · answered Dec 15 '15 at 05:35

1

I think You should extend your main class with AppCompatActivity and use Listfragment instead of ListActivity and u will achieve what u want.

answered Dec 15 '15 at 05:35

Kapil Rajput

11,429
9
50
65

score 1 · Answer 2 · answered Dec 15 '15 at 06:00

1

You'r creating a instance of your Activity class which is totally wrong. You should use like this way

AppCompatActivity appActivity = (AppCompatActivity)ToLines.this
appActivity.setSupportActionBar(toolbar);
appActivity.getSupportActionBar().setDisplayHomeAsUpEnabled(true);

answered Dec 15 '15 at 06:00

Piyush

18,895
5
32
63

is this code (AppCompatActivity)ToLines.this ended by ";"? when i try your code, this code (AppCompatActivity)ToLines.this; has red line and writen "Inconvertible types" – Peternak Kode Channel Dec 15 '15 at 06:17
You should end with `";"` – Piyush Dec 15 '15 at 06:21
yup, I have added ";" then got that red line writen "Inconvertible types" – Peternak Kode Channel Dec 15 '15 at 06:35
Hi Piyush Gupta, how about this http://stackoverflow.com/questions/10787159/android-call-an-method-from-another-class which suggest to do like this Class2 cls2= new Class2(); cls2.UpdateEmployee();? – Peternak Kode Channel Dec 16 '15 at 03:59

How to instance AppCompatActivity in ListView parent?

2 Answers2