blocks|key|1043427|text|您可以简单地检查是否存在空文件，如果它不存在，则执行您的代码并创建该文件。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1043428|例如：|1043429|if(File.Exists("emptyfile"){
++++//Your+code+here
++++File.Create("emptyfile");
}|code-block|syntax|javascript|1043430|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

You could simply check for the existence of an empty file, if it doesn't exist, then execute your code and create the file.

e.g.

<pre><code>if(File.Exists("emptyfile"){
 //Your code here
 File.Create("emptyfile");
}
</code></pre>

blocks|key|1043555|text|另一个想法是使用共享首选项中的设置。与检查空文件的一般概念相同，但这样就不会有空文件到处浮动，不会被用来存储任何内容|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1043556|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|$]]

Another idea is to use a setting in the Shared Preferences. Same general idea as checking for an empty file, but then you don't have an empty file floating around, not being used to store anything

blocks|key|828639|text|这是一些代码-|type|unstyled|depth|inlineStyleRanges|entityRanges|data|828640|String+path+=+Environment.getExternalStorageDirectory().getAbsolutePath()+%2B
++++++++++++++++++++"/Android/data/myapp/files/myfile.txt";

boolean+exists+=+(new+File(path)).exists();+

if+(!exists)+{
++++doSomething();++++++++++++++++++++++++++++++++++++++
}
else+{
++++doSomethingElse();
}|code-block|syntax|javascript|828641|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|$]]

Here's some code for this - 

<pre><code>String path = Environment.getExternalStorageDirectory().getAbsolutePath() +
 "/Android/data/myapp/files/myfile.txt";

boolean exists = (new File(path)).exists(); 

if (!exists) {
 doSomething(); 
}
else {
 doSomethingElse();
}
</code></pre>

blocks|key|828650|text|++++/**
+++++*+@author+ALGO
+++++*/
++++import+java.io.File;
++++import+java.io.FileOutputStream;
++++import+java.io.IOException;
++++import+java.io.RandomAccessFile;
++++import+java.util.UUID;

++++import+android.content.Context;

++++public+class+Util+{
++++++++//+===========================================================
++++++++//
++++++++//+===========================================================

++++++++private+static+final+String+INSTALLATION+=+"INSTALLATION";

++++++++public+synchronized+static+boolean+isFirstLaunch(Context+context)+{
++++++++++++String+sID+=+null;
++++++++++++boolean+launchFlag+=+false;
++++++++++++if+(sID+==+null)+{
++++++++++++++++File+installation+=+new+File(context.getFilesDir(),+INSTALLATION);
++++++++++++++++try+{
++++++++++++++++++++if+(!installation.exists())+{

++++++++++++++++++++++++writeInstallationFile(installation);
++++++++++++++++++++}
++++++++++++++++++++sID+=+readInstallationFile(installation);
launchFlag+=+true;
++++++++++++++++}+catch+(Exception+e)+{
++++++++++++++++++++throw+new+RuntimeException(e);
++++++++++++++++}
++++++++++++}
++++++++++++return+launchFlag;
++++++++}

++++++++private+static+String+readInstallationFile(File+installation)+throws+IOException+{
++++++++++++RandomAccessFile+f+=+new+RandomAccessFile(installation,+"r");//+read+only+mode
++++++++++++byte[]+bytes+=+new+byte[(int)+f.length()];
++++++++++++f.readFully(bytes);
++++++++++++f.close();

++++++++++++return+new+String(bytes);
++++++++}

++++++++private+static+void+writeInstallationFile(File+installation)+throws+IOException+{
++++++++++++FileOutputStream+out+=+new+FileOutputStream(installation);
++++++++++++String+id+=+UUID.randomUUID().toString();
++++++++++++out.write(id.getBytes());
++++++++++++out.close();
++++++++}
++++}

>+Usage+(in+class+extending+android.app.Activity)

Util.isFirstLaunch(this);|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|828651|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> /**
 * @author ALGO
 */
 import java.io.File;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.RandomAccessFile;
 import java.util.UUID;

 import android.content.Context;

 public class Util {
 // ===========================================================
 //
 // ===========================================================

 private static final String INSTALLATION = "INSTALLATION";

 public synchronized static boolean isFirstLaunch(Context context) {
 String sID = null;
 boolean launchFlag = false;
 if (sID == null) {
 File installation = new File(context.getFilesDir(), INSTALLATION);
 try {
 if (!installation.exists()) {

 writeInstallationFile(installation);
 }
 sID = readInstallationFile(installation);
launchFlag = true;
 } catch (Exception e) {
 throw new RuntimeException(e);
 }
 }
 return launchFlag;
 }

 private static String readInstallationFile(File installation) throws IOException {
 RandomAccessFile f = new RandomAccessFile(installation, "r");// read only mode
 byte[] bytes = new byte[(int) f.length()];
 f.readFully(bytes);
 f.close();

 return new String(bytes);
 }

 private static void writeInstallationFile(File installation) throws IOException {
 FileOutputStream out = new FileOutputStream(installation);
 String id = UUID.randomUUID().toString();
 out.write(id.getBytes());
 out.close();
 }
 }

&gt; Usage (in class extending android.app.Activity)

Util.isFirstLaunch(this);
</code></pre>

blocks|key|828701|text|我建议不仅要存储布尔标志，还要存储完整的版本代码。这样，您还可以在开始时查询它是否是新版本中的第一个开始。例如，您可以使用此信息来显示“What+new”对话框。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|828702|下面的代码应该在任何“是上下文”的android类中工作(活动，服务，...)。如果你喜欢把它放在一个单独的(POJO)类中，你可以考虑使用“静态上下文”，比如here。|offset|length|828703|/**
+*+Distinguishes+different+kinds+of+app+starts:+<li>
+*+<ul>
+*+First+start+ever+({@link+#FIRST_TIME})
+*+</ul>
+*+<ul>
+*+First+start+in+this+version+({@link+#FIRST_TIME_VERSION})
+*+</ul>
+*+<ul>
+*+Normal+app+start+({@link+#NORMAL})
+*+</ul>
+*+
+*+@author+schnatterer
+*+
+*/
public+enum+AppStart+{
++++FIRST_TIME,+FIRST_TIME_VERSION,+NORMAL;
}

/**
+*+The+app+version+code+(not+the+version+name!)+that+was+used+on+the+last
+*+start+of+the+app.
+*/
private+static+final+String+LAST_APP_VERSION+=+"last_app_version";

/**
+*+Finds+out+started+for+the+first+time+(ever+or+in+the+current+version). 
+*+ 
+*+Note:+This+method+is+not+idempotent+only+the+first+call+will
+*+determine+the+proper+result.+Any+subsequent+calls+will+only+return
+*+{@link+AppStart#NORMAL}+until+the+app+is+started+again.+So+you+might+want
+*+to+consider+caching+the+result!
+*+
+*+@return+the+type+of+app+start
+*/
public+AppStart+checkAppStart()+{
++++PackageInfo+pInfo;
++++SharedPreferences+sharedPreferences+=+PreferenceManager
++++++++++++.getDefaultSharedPreferences(this);
++++AppStart+appStart+=+AppStart.NORMAL;
++++try+{
++++++++pInfo+=+getPackageManager().getPackageInfo(getPackageName(),+0);
++++++++int+lastVersionCode+=+sharedPreferences
++++++++++++++++.getInt(LAST_APP_VERSION,+-1);
++++++++int+currentVersionCode+=+pInfo.versionCode;
++++++++appStart+=+checkAppStart(currentVersionCode,+lastVersionCode);
++++++++//+Update+version+in+preferences
++++++++sharedPreferences.edit()
++++++++++++++++.putInt(LAST_APP_VERSION,+currentVersionCode).commit();
++++}+catch+(NameNotFoundException+e)+{
++++++++Log.w(Constants.LOG,
++++++++++++++++"Unable+to+determine+current+app+version+from+pacakge+manager.+Defenisvely+assuming+normal+app+start.");
++++}
++++return+appStart;
}

public+AppStart+checkAppStart(int+currentVersionCode,+int+lastVersionCode)+{
++++if+(lastVersionCode+==+-1)+{
++++++++return+AppStart.FIRST_TIME;
++++}+else+if+(lastVersionCode+<+currentVersionCode)+{
++++++++return+AppStart.FIRST_TIME_VERSION;
++++}+else+if+(lastVersionCode+>+currentVersionCode)+{
++++++++Log.w(Constants.LOG,+"Current+version+code+("+%2B+currentVersionCode
++++++++++++++++%2B+")+is+less+then+the+one+recognized+on+last+startup+("
++++++++++++++++%2B+lastVersionCode
++++++++++++++++%2B+").+Defenisvely+assuming+normal+app+start.");
++++++++return+AppStart.NORMAL;
++++}+else+{
++++++++return+AppStart.NORMAL;
++++}
}|code-block|syntax|javascript|828704|它可以在下面这样的活动中使用：|828705|public+class+MainActivity+extends+Activity+{++++++++
++++@Override
++++protected+void+onCreate(Bundle+savedInstanceState)+{
++++++++super.onCreate(savedInstanceState);

++++++++switch+(checkAppStart())+{
++++++++case+NORMAL:
++++++++++++//+We+don't+want+to+get+on+the+user's+nerves
++++++++++++break;
++++++++case+FIRST_TIME_VERSION:
++++++++++++//+TODO+show+what's+new
++++++++++++break;
++++++++case+FIRST_TIME:
++++++++++++//+TODO+show+a+tutorial
++++++++++++break;
++++++++default:
++++++++++++break;
++++++++}

++++++++//+...
++++}
++++//+...
}|828706|可以使用以下JUnit测试来验证基本逻辑：|828707|public+void+testCheckAppStart()+{
++++//+First+start
++++int+oldVersion+=+-1;
++++int+newVersion+=+1;
++++assertEquals("Unexpected+result",+AppStart.FIRST_TIME,
++++++++++++service.checkAppStart(newVersion,+oldVersion));

++++//+First+start+this+version
++++oldVersion+=+1;
++++newVersion+=+2;
++++assertEquals("Unexpected+result",+AppStart.FIRST_TIME_VERSION,
++++++++++++service.checkAppStart(newVersion,+oldVersion));

++++//+Normal+start
++++oldVersion+=+2;
++++newVersion+=+2;
++++assertEquals("Unexpected+result",+AppStart.NORMAL,
++++++++++++service.checkAppStart(newVersion,+oldVersion));
}|828708|多花点功夫，你可能也可以测试与安卓相关的东西(PackageManager和SharedPreferences)。有没有人有兴趣写测试？:)|828709|请注意，只有在AndroidManifest.xml中不修改android:versionCode的情况下，上面的代码才能正常工作！|style|CODE|828710|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/2002288/static-way-to-get-context-on-android/5114361#5114361^0|0|28|4|0|0|0|0|0|0|0|0|U|J|0^^$0|@$1|2|3|4|5|6|7|16|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|17|8|@]|9|@$D|18|E|19|1|1A]]|A|$]]|$1|F|3|G|5|H|7|1B|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|1C|8|@]|9|@]|A|$]]|$1|M|3|N|5|H|7|1D|8|@]|9|@]|A|$I|J]]|$1|O|3|P|5|6|7|1E|8|@]|9|@]|A|$]]|$1|Q|3|R|5|H|7|1F|8|@]|9|@]|A|$I|J]]|$1|S|3|T|5|6|7|1G|8|@]|9|@]|A|$]]|$1|U|3|V|5|6|7|1H|8|@$D|1I|E|1J|W|X]]|9|@]|A|$]]|$1|Y|3|-4|5|6|7|1K|8|@]|9|@]|A|$]]]|Z|$10|$5|11|12|13|A|$14|15]]]]

I suggest to not only store a boolean flag, but the complete version code.
This way you can also query at the beginning if it is the first start in a new version. You can use this information to display a "Whats new" dialog, for example.

The following code should work from any android class that "is a context" (activities, services, ...). If you prefer to have it in a separate (POJO) class, you could consider using a "static context", as described <a href="https://stackoverflow.com/questions/2002288/static-way-to-get-context-on-android/5114361#5114361">here</a> for example.

<pre><code>/**
 * Distinguishes different kinds of app starts: &lt;li&gt;
 * &lt;ul&gt;
 * First start ever ({@link #FIRST_TIME})
 * &lt;/ul&gt;
 * &lt;ul&gt;
 * First start in this version ({@link #FIRST_TIME_VERSION})
 * &lt;/ul&gt;
 * &lt;ul&gt;
 * Normal app start ({@link #NORMAL})
 * &lt;/ul&gt;
 * 
 * @author schnatterer
 * 
 */
public enum AppStart {
 FIRST_TIME, FIRST_TIME_VERSION, NORMAL;
}

/**
 * The app version code (not the version name!) that was used on the last
 * start of the app.
 */
private static final String LAST_APP_VERSION = "last_app_version";

/**
 * Finds out started for the first time (ever or in the current version).&lt;br/&gt;
 * &lt;br/&gt;
 * Note: This method is &lt;b&gt;not idempotent&lt;/b&gt; only the first call will
 * determine the proper result. Any subsequent calls will only return
 * {@link AppStart#NORMAL} until the app is started again. So you might want
 * to consider caching the result!
 * 
 * @return the type of app start
 */
public AppStart checkAppStart() {
 PackageInfo pInfo;
 SharedPreferences sharedPreferences = PreferenceManager
 .getDefaultSharedPreferences(this);
 AppStart appStart = AppStart.NORMAL;
 try {
 pInfo = getPackageManager().getPackageInfo(getPackageName(), 0);
 int lastVersionCode = sharedPreferences
 .getInt(LAST_APP_VERSION, -1);
 int currentVersionCode = pInfo.versionCode;
 appStart = checkAppStart(currentVersionCode, lastVersionCode);
 // Update version in preferences
 sharedPreferences.edit()
 .putInt(LAST_APP_VERSION, currentVersionCode).commit();
 } catch (NameNotFoundException e) {
 Log.w(Constants.LOG,
 "Unable to determine current app version from pacakge manager. Defenisvely assuming normal app start.");
 }
 return appStart;
}

public AppStart checkAppStart(int currentVersionCode, int lastVersionCode) {
 if (lastVersionCode == -1) {
 return AppStart.FIRST_TIME;
 } else if (lastVersionCode &lt; currentVersionCode) {
 return AppStart.FIRST_TIME_VERSION;
 } else if (lastVersionCode &gt; currentVersionCode) {
 Log.w(Constants.LOG, "Current version code (" + currentVersionCode
 + ") is less then the one recognized on last startup ("
 + lastVersionCode
 + "). Defenisvely assuming normal app start.");
 return AppStart.NORMAL;
 } else {
 return AppStart.NORMAL;
 }
}
</code></pre>

It could be used from an activity like this:

<pre><code>public class MainActivity extends Activity { 
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);

 switch (checkAppStart()) {
 case NORMAL:
 // We don't want to get on the user's nerves
 break;
 case FIRST_TIME_VERSION:
 // TODO show what's new
 break;
 case FIRST_TIME:
 // TODO show a tutorial
 break;
 default:
 break;
 }

 // ...
 }
 // ...
}
</code></pre>

The basic logic can be verified using this JUnit test:

<pre><code>public void testCheckAppStart() {
 // First start
 int oldVersion = -1;
 int newVersion = 1;
 assertEquals("Unexpected result", AppStart.FIRST_TIME,
 service.checkAppStart(newVersion, oldVersion));

 // First start this version
 oldVersion = 1;
 newVersion = 2;
 assertEquals("Unexpected result", AppStart.FIRST_TIME_VERSION,
 service.checkAppStart(newVersion, oldVersion));

 // Normal start
 oldVersion = 2;
 newVersion = 2;
 assertEquals("Unexpected result", AppStart.NORMAL,
 service.checkAppStart(newVersion, oldVersion));
}
</code></pre>

With a bit more effort you could probably test the android related stuff (PackageManager and SharedPreferences) as well.
Anyone interested in writing the test? :)

Note that the above code will only work properly if you don't mess around with your <code>android:versionCode</code> in AndroidManifest.xml!

blocks|key|828757|text|为什么不使用Database+Helper？这将有一个很好的onCreate，它只在应用程序第一次启动时调用。这将帮助那些想要在没有跟踪的情况下安装初始应用程序后跟踪此内容的人。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|828758|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|$]]

Why not use the Database Helper ? This will have a nice onCreate which is only called the first time the app is started. This will help those people who want to track this after there initial app has been installed without tracking.

blocks|key|1043720|text|我喜欢在我的共享首选项中有一个“更新计数”。如果它不在那里(或缺省为零值)，那么这是我的应用程序的“第一次使用”。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1043721|private+static+final+int+UPDATE_COUNT+=+1;++++//+Increment+this+on+major+change
...
if+(sp.getInt("updateCount",+0)+==+0)+{
++++//+first+use
}+else+if+(sp.getInt("updateCount",+0)+<+UPDATE_COUNT)+{
++++//+Pop+up+dialog+telling+user+about+new+features
}
...
sp.edit().putInt("updateCount",+UPDATE_COUNT);|code-block|syntax|javascript|1043722|所以现在，每当有用户应该知道的应用程序更新时，我都会递增UPDATE_COUNT|1043723|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

I like to have an "update count" in my shared preferences. If it's not there (or default zero value) then this is my app's "first use".

<pre><code>private static final int UPDATE_COUNT = 1; // Increment this on major change
...
if (sp.getInt("updateCount", 0) == 0) {
 // first use
} else if (sp.getInt("updateCount", 0) &lt; UPDATE_COUNT) {
 // Pop up dialog telling user about new features
}
...
sp.edit().putInt("updateCount", UPDATE_COUNT);
</code></pre>

So now, whenever there's an update to the app that users should know about, I increment UPDATE_COUNT

blocks|key|1043749|text|在支持库版本23.3.0+(在v4中，这意味着兼容性回到Android1.6)中就有对此的支持。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1043750|在您的启动器活动中，首先调用：|1043751|AppLaunchChecker.onActivityCreate(activity);|code-block|syntax|javascript|1043752|然后调用：|1043753|AppLaunchChecker.hasStartedFromLauncher(activity);|1043754|如果这是该应用程序第一次启动，它将返回。|1043755|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|T|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

There is support for just this in the support library revision 23.3.0 (in the v4 which means compability back to Android 1.6).

In your Launcher activity, first call:

<pre><code>AppLaunchChecker.onActivityCreate(activity);
</code></pre>

Then call:

<pre><code>AppLaunchChecker.hasStartedFromLauncher(activity);
</code></pre>

Which will return if this was the first time the app was launched.

blocks|key|828853|text|如果你正在寻找一种简单的方法，它就在这里。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|828854|像这样创建一个实用程序类，|828855|public+class+ApplicationUtils+{

++/**
++*+Sets+the+boolean+preference+value
++*
++*+@param+context+the+current+context
++*+@param+key+++++the+preference+key
++*+@param+value+++the+value+to+be+set
++*/
+public+static+void+setBooleanPreferenceValue(Context+context,+String+key,+boolean+value)+{
+++++SharedPreferences+sp+=+PreferenceManager.getDefaultSharedPreferences(context);
+++++sp.edit().putBoolean(key,+value).apply();
+}

+/**
++*+Get+the+boolean+preference+value+from+the+SharedPreference
++*
++*+@param+context+the+current+context
++*+@param+key+++++the+preference+key
++*+@return+the+the+preference+value
++*/
+public+static+boolean+getBooleanPreferenceValue(Context+context,+String+key)+{
+++++SharedPreferences+sp+=+PreferenceManager.getDefaultSharedPreferences(context);
+++++return+sp.getBoolean(key,+false);
+}

}|code-block|syntax|javascript|828856|在您的主要活动中，onCreate()|828857|if(!ApplicationUtils.getBooleanPreferenceValue(this,"isFirstTimeExecution")){
Log.d(TAG,+"First+time+Execution");
ApplicationUtils.setBooleanPreferenceValue(this,"isFirstTimeExecution",true);
//+do+your+first+time+execution+stuff+here,
}|828858|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Q|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

If you are looking for a simple way, here it is.

Create a utility class like this,

<pre><code>public class ApplicationUtils {

 /**
 * Sets the boolean preference value
 *
 * @param context the current context
 * @param key the preference key
 * @param value the value to be set
 */
 public static void setBooleanPreferenceValue(Context context, String key, boolean value) {
 SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(context);
 sp.edit().putBoolean(key, value).apply();
 }

 /**
 * Get the boolean preference value from the SharedPreference
 *
 * @param context the current context
 * @param key the preference key
 * @return the the preference value
 */
 public static boolean getBooleanPreferenceValue(Context context, String key) {
 SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(context);
 return sp.getBoolean(key, false);
 }

}
</code></pre>

At your Main Activity, onCreate()

<pre><code>if(!ApplicationUtils.getBooleanPreferenceValue(this,"isFirstTimeExecution")){
Log.d(TAG, "First time Execution");
ApplicationUtils.setBooleanPreferenceValue(this,"isFirstTimeExecution",true);
// do your first time execution stuff here,
}
</code></pre>

blocks|key|828864|text|对于kotlin|type|unstyled|depth|inlineStyleRanges|entityRanges|data|828865|++++fun+checkFirstRun()+{

++++var+prefs_name+=+"MyPrefsFile"
++++var+pref_version_code_key+=+"version_code"
++++var+doesnt_exist:+Int+=+-1;

++++//+Get+current+version+code
++++var+currentVersionCode+=+BuildConfig.VERSION_CODE

++++//+Get+saved+version+code
++++var+prefs:+SharedPreferences+=+getSharedPreferences(prefs_name,+MODE_PRIVATE)
++++var+savedVersionCode:+Int+=+prefs.getInt(pref_version_code_key,+doesnt_exist)

++++//+Check+for+first+run+or+upgrade
++++if+(currentVersionCode+==+savedVersionCode)+{

++++++++//+This+is+just+a+normal+run
++++++++return;

++++}+else+if+(savedVersionCode+==+doesnt_exist)+{

++++++++//+TODO+This+is+a+new+install+(or+the+user+cleared+the+shared+preferences)


++++}+else+if+(currentVersionCode+>+savedVersionCode)+{

++++++++//+TODO+This+is+an+upgrade
++++}

++++//+Update+the+shared+preferences+with+the+current+version+code
++++prefs.edit().putInt(pref_version_code_key,+currentVersionCode).apply();

}|code-block|syntax|javascript|828866|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 kotlin

<pre><code> fun checkFirstRun() {

 var prefs_name = "MyPrefsFile"
 var pref_version_code_key = "version_code"
 var doesnt_exist: Int = -1;

 // Get current version code
 var currentVersionCode = BuildConfig.VERSION_CODE

 // Get saved version code
 var prefs: SharedPreferences = getSharedPreferences(prefs_name, MODE_PRIVATE)
 var savedVersionCode: Int = prefs.getInt(pref_version_code_key, doesnt_exist)

 // Check for first run or upgrade
 if (currentVersionCode == savedVersionCode) {

 // This is just a normal run
 return;

 } else if (savedVersionCode == doesnt_exist) {

 // TODO This is a new install (or the user cleared the shared preferences)


 } else if (currentVersionCode &gt; savedVersionCode) {

 // TODO This is an upgrade
 }

 // Update the shared preferences with the current version code
 prefs.edit().putInt(pref_version_code_key, currentVersionCode).apply();

}
</code></pre>

blocks|key|1043827|text|我的kotlin版本如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1043828|PreferenceManager.getDefaultSharedPreferences(this).apply+{
++++++++//+Check+if+we+need+to+display+our+OnboardingSupportFragment
++++++++if+(!getBoolean("wasAppStartedPreviously",+false))+{
++++++++++++//+The+user+hasn't+seen+the+OnboardingSupportFragment+yet,+so+show+it
++++++++++++startActivity(Intent(this@SplashScreenActivity,+AppIntroActivity::class.java))
++++++++}+else+{
++++++++++++startActivity(Intent(this@SplashScreenActivity,+MainActivity::class.java))
++++++++}
++++}|code-block|syntax|javascript|1043829|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|$]]

My version for kotlin looks like the following:
<pre><code>PreferenceManager.getDefaultSharedPreferences(this).apply {
 // Check if we need to display our OnboardingSupportFragment
 if (!getBoolean(&quot;wasAppStartedPreviously&quot;, false)) {
 // The user hasn't seen the OnboardingSupportFragment yet, so show it
 startActivity(Intent(this@SplashScreenActivity, AppIntroActivity::class.java))
 } else {
 startActivity(Intent(this@SplashScreenActivity, MainActivity::class.java))
 }
 }
</code></pre>

I am currently developing an android app. I need to do something when the app is launched for the first time, i.e. the code only runs on the first time the program is launched.

Determine if Android app is being used for the first time

Android

我目前正在开发一个android应用程序。当应用程序第一次启动时，我需要做一些事情，即代码只在程序第一次启动时运行。

问确定是否为首次使用Android应用程序
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