performance - Switching between Android activities increasing memory usage -

an app consists of 3 activities: activity a, b , c. each activity has "singletop" set launch mode.

all 3 activities have default "hello world!" textview , button. button in activity starts activity b , 1 in activity b starts activity c. code use:

    public void startactivityb(view v){         intent = new intent(a.this, b.class);         i.addflags(intent.flag_activity_single_top|intent.flag_activity_clear_top);         startactivity(i);     } 

the button in activity c finishes using finish()

i know there similar questions have tried every single thing make work nothing has worked me. problem if navigate b , b c, c b , b using android's button, , repeat process several times, reason there several instances of each activity, except a, running. used mat check , there several objects of each class when there should 1 of each.

my concern happening memory app uses keeps increasing end in app getting "oom" error.

am doing wrong or missing something?

activity a

package com.test.testapp;  import android.content.intent; import android.support.v7.app.actionbaractivity; import android.os.bundle; import android.view.view;   public class extends actionbaractivity {      @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_a);     }      public void startactivityb(view v){         intent = new intent(a.this, b.class);         i.addflags(intent.flag_activity_single_top|intent.flag_activity_clear_top);         startactivity(i);     } } 

activity b

package com.test.testapp;  import android.content.intent; import android.support.v7.app.actionbaractivity; import android.os.bundle; import android.view.view;   public class b extends actionbaractivity {      @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_b);     }      public void startactivityc(view v) {         intent = new intent(b.this, c.class);         i.addflags(intent.flag_activity_single_top | intent.flag_activity_clear_top);         startactivity(i);     } } 

activity c

package com.test.testapp;  import android.support.v7.app.actionbaractivity; import android.os.bundle; import android.view.view;   public class c extends actionbaractivity {      @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_c);     }      public void closeactivity(view v){         finish();     }  } 

update

activities still have several instances when changing launch mode , starting them different intent flags. reason if call finish() on activities problem persists.