Listviewをタップしてnew intentに飛ばしたい

listviewにアダプターを設定するまではいいのですが、onitemclickがうまくいきません。

クリックすると、Unfortunately the app has stopped と出てしまいます。

なぜでしょうか？

エラー

android.content.ActivityNotFoundException: Unable to find explicit activity class {com.example.tsuyoshiokaprofile/com.example.tsuyoshiokaprofile.sub_activity}; have you declared this activity in your AndroidManifest.xml?
                                                                                  at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1777)
                                                                                  at android.app.Instrumentation.execStartActivity(Instrumentation.java:1501)
                                                                                  at android.app.Activity.startActivityForResult(Activity.java:3745)
                                                                                  at android.app.Activity.startActivityForResult(Activity.java:3706)
                                                                                  at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:843)
                                                                                  at android.app.Activity.startActivity(Activity.java:4016)
                                                                                  at android.app.Activity.startActivity(Activity.java:3984)
                                                                                  at com.example.tsuyoshiokaprofile.Main$1.onItemClick(Main.java:48)
                                                                                  at android.widget.AdapterView.performItemClick(AdapterView.java:305)
                                                                                  at android.widget.AbsListView.performItemClick(AbsListView.java:1146)
                                                                                  at android.widget.AbsListView$PerformClick.run(AbsListView.java:3053)
                                                                                  at android.widget.AbsListView$3.run(AbsListView.java:3860)
                                                                                  at android.os.Handler.handleCallback(Handler.java:739)
                                                                                  at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                                  at android.os.Looper.loop(Looper.java:135)
                                                                                  at android.app.ActivityThread.main(ActivityThread.java:5254)
                                                                                  at java.lang.reflect.Method.invoke(Native Method)
                                                                                  at java.lang.reflect.Method.invoke(Method.java:372)
                                                                                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
                                                                                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

 @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //content.xmlからidを取得
        ListView listView = (ListView)findViewById(R.id.listView1);

        //配列を保持するアダプターのインスタンスと引数を設定
        ArrayAdapter<String> arrayAdapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, profiles);

        //アダプターをリストビューのインスタンスに設定
        listView.setAdapter(arrayAdapter);


        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

                ListView listView = (ListView) parent;
                Intent sub = new Intent();
                sub.setClassName("com.example.tsuyoshiokaprofile", "com.example.tsuyoshiokaprofile.sub_activity");
                startActivity(sub);


            }
        });