清除整個歷史記錄堆棧並在Android上啓動新活動

本文翻譯自：Clear the entire history stack and start a new activity on Android

Is it possible to start an activity on the stack, clearing the entire history before it? 是否可以在堆棧上啓動活動，清除之前的整個歷史記錄？

The situation 情況

I have an activity stack that either goes A->B->C or B->C (screen A selects the users token, but many users only have a single token). 我有一個活動堆棧，可以是A-> B-> C或B-> C（屏幕A選擇用戶令牌，但許多用戶只有一個令牌）。

In screen C the user may take an action which makes screen B invalid, so the application wants to take them to screen A, regardless of whether it is already in the stack. 在屏幕C中，用戶可以採取使屏幕B無效的動作，因此應用程序想要將它們帶到屏幕A，而不管它是否已經在堆棧中。 Screen A should then be the only item on the stack in my application. 屏幕A應該是我的應用程序中堆棧上唯一的項目。

Notes 筆記

There are many other similar questions, but I haven't found anything that answers this exact question. 還有許多其他類似的問題，但我沒有發現任何可以回答這個問題的問題。 I tried calling getParent().finish() - this always results in a null pointer exception. 我試着調用getParent().finish() - 這總是會導致空指針異常。 FLAG_ACTIVITY_CLEAR_TOP only works if the activity is already on the stack. FLAG_ACTIVITY_CLEAR_TOP僅在活動已在堆棧上時纔有效。

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#1樓

參考：https://stackoom.com/question/EZWq/清除整個歷史記錄堆棧並在Android上啓動新活動

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#2樓

在使用startActivity開始新活動startActivity ，請確保調用finish()以便當前活動不會堆疊在新活動後面。

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#3樓

Case 1:Only two activity A and B: 案例1：只有兩個活動A和B：

Here Activity flow is A->B .On clicking backbutton from B we need to close the application then while starting Activity B from A just call finish() this will prevent android from storing Activity A in to the Backstack.eg for activity A is Loding/Splash screen of application. 這裏的活動流程是A-> B.點擊B的後退按鈕我們需要關閉應用程序然後從A啓動活動B只調用finish（）這將阻止android將活動A存儲到Backstack.eg中，活動A是Loding / Splash應用程序屏幕。

Intent newIntent = new Intent(A.this, B.class);
startActivity(newIntent);
finish();

Case 2:More than two activitiy: 案例2：兩個以上的活動：

If there is a flow like A->B->C->D->B and on clicking back button in Activity B while coming from Activity D.In that case we should use. 如果有來自活動D的A-> B-> C-> D-> B之類的流程以及活動B中的單擊後退按鈕。在這種情況下我們應該使用。

Intent newIntent = new Intent(D.this,B.class);
newIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); 
newIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(newIntent);

Here Activity B will be started from the backstack rather than a new instance because of Intent.FLAG_ACTIVITY_CLEAR_TOP and Intent.FLAG_ACTIVITY_NEW_TASK clears the stack and makes it the top one.So when we press back button the whole application will be terminated. 這裏活動B將從backstack而不是新實例啓動，因爲Intent.FLAG_ACTIVITY_CLEAR_TOP和Intent.FLAG_ACTIVITY_NEW_TASK清除堆棧並使其成爲最重要的一個。所以當我們按下後退按鈕時，整個應用程序將被終止。

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#4樓

I spent a few hours on this too ... and agree that FLAG_ACTIVITY_CLEAR_TOP sounds like what you'd want: clear the entire stack, except for the activity being launched, so the Back button exits the application. 我也花了幾個小時...並且同意FLAG_ACTIVITY_CLEAR_TOP聽起來像你想要的那樣：清除整個堆棧，除了正在啓動的活動，所以Back按鈕退出應用程序。 Yet as Mike Repass mentioned, FLAG_ACTIVITY_CLEAR_TOP only works when the activity you're launching is already in the stack; 然而正如Mike Repass所提到的，FLAG_ACTIVITY_CLEAR_TOP僅在你正在啓動的活動已經在堆棧中時起作用; when the activity's not there, the flag doesn't do anything. 當活動不存在時，旗幟不做任何事情。

What to do? 該怎麼辦？ Put the activity being launching in the stack with FLAG_ACTIVITY_NEW_TASK, which makes that activity the start of a new task on the history stack. 使用FLAG_ACTIVITY_NEW_TASK將正在啓動的活動放入堆棧，這使得該活動成爲歷史堆棧上新任務的開始。 Then add the FLAG_ACTIVITY_CLEAR_TOP flag. 然後添加FLAG_ACTIVITY_CLEAR_TOP標誌。

Now, when FLAG_ACTIVITY_CLEAR_TOP goes to find the new activity in the stack, it'll be there and be pulled up before everything else is cleared. 現在，當FLAG_ACTIVITY_CLEAR_TOP用於在堆棧中查找新活動時，它將存在並在其他所有清除之前被拉起。

Here's my logout function; 這是我的退出功能; the View parameter is the button to which the function's attached. View參數是函數附加的按鈕。

public void onLogoutClick(final View view) {
    Intent i = new Intent(this, Splash.class);
    i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
    startActivity(i);
    finish();
}

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#5樓

You shouldn't change the stack. 你不應該改變堆棧。 Android back button should work as in a web browser. Android後退按鈕應該像在Web瀏覽器中一樣工作。

I can think of a way to do it, but it's quite a hack. 我可以想辦法做到這一點，但這是一個非常黑客。

• Make your Activities singleTask by adding it to the AndroidManifest Example: 將您的活動singleTask添加到AndroidManifest示例中：

   <activity android:name=".activities.A" android:label="@string/A_title" android:launchMode="singleTask"/> <activity android:name=".activities.B" android:label="@string/B_title" android:launchMode="singleTask"/> 

• Extend Application which will hold the logic of where to go. 擴展Application ，它將掌握去哪裏的邏輯。

Example: 例：

public class DontHackAndroidLikeThis extends Application {

  private Stack<Activity> classes = new Stack<Activity>();

  public Activity getBackActivity() {
    return classes.pop();
  }

  public void addBackActivity(Activity activity) {
    classes.push(activity);
  }
}

From A to B: 從A到B：

DontHackAndroidLikeThis app = (DontHackAndroidLikeThis) getApplication();
app.addBackActivity(A.class); 
startActivity(this, B.class);

From B to C: 從B到C：

DontHackAndroidLikeThis app = (DontHackAndroidLikeThis) getApplication();
app.addBackActivity(B.class); 
startActivity(this, C.class);

In C: 在C：

If ( shouldNotGoBackToB() ) {
  DontHackAndroidLikeThis app = (DontHackAndroidLikeThis) getApplication();
  app.pop();
}

and handle the back button to pop() from the stack. 並從堆棧處理後退按鈕pop() 。

Once again, you shouldn't do this :) 再一次，你不應該這樣做:)

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#6樓

I found too simple hack just do this add new element in AndroidManifest as:- 我發現太簡單的黑客只是在AndroidManifest添加新元素： -

<activity android:name=".activityName"
          android:label="@string/app_name"
          android:noHistory="true"/>

the android:noHistory will clear your unwanted activity from Stack. android:noHistory將清除Stack中不需要的活動。