blocks|key|593023|text|在我的例子中，LoginActivity也被关闭了。结果,|type|unstyled|depth|inlineStyleRanges|entityRanges|data|593024|Intent.FLAG_ACTIVITY_CLEAR_TOP+%7C+Intent.FLAG_ACTIVITY_CLEAR_TASK|code-block|syntax|javascript|593025|无济于事。|593026|但是，设置|593027|Intent.FLAG_ACTIVITY_NEW_TASK|593028|帮了我。|593029|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|T|8|@]|9|@]|A|$]]|$1|K|3|L|5|D|7|U|8|@]|9|@]|A|$E|F]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

In my case, LoginActivity was closed as well. As a result, 

<pre><code>Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_CLEAR_TASK
</code></pre>

did not help.

However, setting 

<pre><code>Intent.FLAG_ACTIVITY_NEW_TASK
</code></pre>

helped me.

blocks|key|593071|text|下面是一个简单的助手方法，用于启动一个新的activity作为新的top+activity，它从API+level+4一直到当前版本17：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|593072|static+void+startNewMainActivity(Activity+currentActivity,+Class<?+extends+Activity>+newTopActivityClass)+{
++++Intent+intent+=+new+Intent(currentActivity,+newTopActivityClass);
++++intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
++++intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
++++if+(Build.VERSION.SDK_INT+>=+Build.VERSION_CODES.HONEYCOMB)
++++++++intent.addFlags(0x8000);+//+equal+to+Intent.FLAG_ACTIVITY_CLEAR_TASK+which+is+only+available+from+API+level+11
++++currentActivity.startActivity(intent);
}|code-block|syntax|javascript|593073|从您当前的活动中这样调用它：|593074|startNewMainActivity(this,+MainActivity.class);|593075|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Here is a simple helper method for starting a new activity as the new top activity which works from API level 4 up until the current version 17:

<pre><code>static void startNewMainActivity(Activity currentActivity, Class&lt;? extends Activity&gt; newTopActivityClass) {
 Intent intent = new Intent(currentActivity, newTopActivityClass);
 intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
 intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
 if (Build.VERSION.SDK_INT &gt;= Build.VERSION_CODES.HONEYCOMB)
 intent.addFlags(0x8000); // equal to Intent.FLAG_ACTIVITY_CLEAR_TASK which is only available from API level 11
 currentActivity.startActivity(intent);
}
</code></pre>

call it like this from your current activity:

<pre><code>startNewMainActivity(this, MainActivity.class);
</code></pre>

blocks|key|593079|text|Intent+intent+=+new+Intent(LoginActivity.this,+Home.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);++//It+is+use+to+finish+current+activity
startActivity(intent);
this.finish();|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|593080|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>Intent intent = new Intent(LoginActivity.this, Home.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); //It is use to finish current activity
startActivity(intent);
this.finish();
</code></pre>

blocks|key|593113|text|这个决定可以很好地工作：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|593114|intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK+%7C+Intent.FLAG_ACTIVITY_CLEAR_TASK);|code-block|syntax|javascript|593115|但是新的活动启动很长时间，你有时会看到白屏。如果这很重要，则使用此解决方法：|593116|public+class+BaseActivity+extends+AppCompatActivity+{

++++private+static+final+String+ACTION_FINISH+=+"action_finish";

++++private+BroadcastReceiver+finisBroadcastReceiver;

++++@Override
++++protected+void+onCreate(Bundle+savedInstanceState)+{
++++++++super.onCreate(savedInstanceState);

++++++++registerReceiver(finisBroadcastReceiver+=+new+BroadcastReceiver()+{
++++++++++++@Override
++++++++++++public+void+onReceive(Context+context,+Intent+intent)+{
++++++++++++++++finish();
++++++++++++}
++++++++},+new+IntentFilter(ACTION_FINISH));
++++}

++++public+void+clearBackStack()+{
++++++++sendBroadcast(new+Intent(ACTION_FINISH));
++++}

++++@Override
++++protected+void+onDestroy()+{
++++++++unregisterReceiver(finisBroadcastReceiver);
++++++++super.onDestroy();
++++}
}|593117|如何使用它：|593118|public+class+ActivityA+extends+BaseActivity+{

++++//+Click+any+button
++++public+void+startActivityB()+{
++++++++startActivity(new+Intent(this,+ActivityB.class));
++++++++clearBackStack();
++++}
}|593119|缺点:堆栈上必须关闭的所有活动都必须扩展BaseActivity|593120|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|W|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|Y|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

This decision works fine: 

<pre><code>intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
</code></pre>

But new activity launch long and you see white screen some time. If this is critical then use this workaround:

<pre><code>public class BaseActivity extends AppCompatActivity {

 private static final String ACTION_FINISH = "action_finish";

 private BroadcastReceiver finisBroadcastReceiver;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);

 registerReceiver(finisBroadcastReceiver = new BroadcastReceiver() {
 @Override
 public void onReceive(Context context, Intent intent) {
 finish();
 }
 }, new IntentFilter(ACTION_FINISH));
 }

 public void clearBackStack() {
 sendBroadcast(new Intent(ACTION_FINISH));
 }

 @Override
 protected void onDestroy() {
 unregisterReceiver(finisBroadcastReceiver);
 super.onDestroy();
 }
}
</code></pre>

How use it:

<pre><code>public class ActivityA extends BaseActivity {

 // Click any button
 public void startActivityB() {
 startActivity(new Intent(this, ActivityB.class));
 clearBackStack();
 }
}
</code></pre>

Disadvantage: all activities that must be closed on the stack must extends BaseActivity

blocks|key|808814|text|对于Xamarin开发人员，您可以使用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|808815|intent.SetFlags(ActivityFlags.NewTask+%7C+ActivityFlags.ClearTask);|code-block|syntax|javascript|808816|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

For Xamarin Developers, you can use:

<pre><code>intent.SetFlags(ActivityFlags.NewTask | ActivityFlags.ClearTask);
</code></pre>

blocks|key|593288|text|使用Kotlin：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|593289|您可以使用setter方法直接设置标志。在Kotlin中，or是表示Java位或%7C的replacement。|offset|length|style|CODE|593290|intent.flags+=+FLAG_ACTIVITY_NEW_TASK+or+FLAG_ACTIVITY_CLEAR_TASK|code-block|syntax|javascript|593291|如果您计划经常使用它，请创建一个意图扩展函数|593292|fun+Intent.clearStack()+{
++++flags+=+Intent.FLAG_ACTIVITY_NEW_TASK+or+Intent.FLAG_ACTIVITY_CLEAR_TASK
}|593293|然后，您可以在启动intent之前直接调用此函数|593294|intent.clearStack()|593295|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/45996002/974045^0|0|T|2|14|1|16|B|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|12|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|13|8|@$D|14|E|15|F|G]|$D|16|E|17|F|G]]|9|@$D|18|E|19|1|1A]]|A|$]]|$1|H|3|I|5|J|7|1B|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|1C|8|@]|9|@]|A|$]]|$1|O|3|P|5|J|7|1D|8|@]|9|@]|A|$K|L]]|$1|Q|3|R|5|6|7|1E|8|@]|9|@]|A|$]]|$1|S|3|T|5|J|7|1F|8|@]|9|@]|A|$K|L]]|$1|U|3|-4|5|6|7|1G|8|@]|9|@]|A|$]]]|V|$W|$5|X|Y|Z|A|$10|11]]]]

<h2>Using Kotlin:</h2>

You can set the flag directly using setter method. In Kotlin <code>or</code> is the <a href="https://stackoverflow.com/a/45996002/974045">replacement</a> for the Java bitwise or <code>|</code>.

<pre><code>intent.flags = FLAG_ACTIVITY_NEW_TASK or FLAG_ACTIVITY_CLEAR_TASK
</code></pre>

If you plan to use this regularly, create an Intent extension function

<pre><code>fun Intent.clearStack() {
 flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
}
</code></pre>

You can then directly call this function before starting the intent

<pre><code>intent.clearStack()
</code></pre>

blocks|key|593339|text|Intent+=新的Intent(LoginActivity.this，MainActivity.class)；intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK+%7C+Intent.FLAG_ACTIVITY_CLEAR_TASK)；startActivity(+intent+)；finish()；|type|unstyled|depth|inlineStyleRanges|entityRanges|data|593340|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Intent intent = new Intent(LoginActivity.this,MainActivity.class); intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
startActivity(intent);
finish();

I'm having several activities in my application. and flow is very complicated. When I click the Logout application navigates to login Screen and from there user can exit by cancel button (calling <code>system.exit(0)</code> )

when I exit or back button, the system invokes an activity from stack :( how can I clear all the activities in the stack when I reach Login screen? calling <code>finish()</code> is not practical as there are so many activities and some activities should no be closed when they are active such as native camera invoking activity.

<pre><code>validateuser logoutuser = new validateuser();
logoutuser.logOut();
Intent loginscreen = new Intent(homepage.this, Login2.class);
(homepage.this).finish();
loginscreen.setFlags( Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_NO_HISTORY);
startActivity(loginscreen);
</code></pre>

Android: Clear Activity Stack

我的应用程序中有几个活动。流程是非常复杂的。当我单击注销应用程序导航到登录屏幕时，用户可以从那里通过取消按钮退出(调用system.exit(0) )当我退出或后退按钮时，系统调用堆栈中的活动:(当我到达登录屏幕时，如何清除堆栈中的所有活动？调用finish()是不实际的，因为有太多的活动，有些活动在活动时不应该关闭，...

问Android:清除活动堆栈
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