How to get app install time from android

i try some method,but not success,help me.

PackageManager pm = context.getPackageManager();
ApplicationInfo appInfo = pm.getApplicationInfo("app.package.name", 0);
String appFile = appInfo.sourceDir;
long installed = new File(appFile).lastModified(); //Epoch Time

In API level 9 (Gingerbread) and above, there's the PackageInfo.firstInstallTime field, holding milliseconds since the epoch:

packageManager.getPackageInfo(packageName, 0).firstInstallTime;

I have the following code to use it if available, and fall back to the apk modification time:

// return install time from package manager, or apk file modification time,
// or null if not found
public Date getInstallTime(
    PackageManager packageManager, String packageName) {
  return firstNonNull(
    installTimeFromPackageManager(packageManager, packageName),
    apkUpdateTime(packageManager, packageName));
}

private Date apkUpdateTime(
    PackageManager packageManager, String packageName) {
  try {
    ApplicationInfo info = packageManager.getApplicationInfo(packageName, 0);
    File apkFile = new File(info.sourceDir);
    return apkFile.exists() ? new Date(apkFile.lastModified()) : null;
  } catch (NameNotFoundException e) {
    return null; // package not found
  }
}

private Date installTimeFromPackageManager(
    PackageManager packageManager, String packageName) {
  // API level 9 and above have the "firstInstallTime" field.
  // Check for it with reflection and return if present. 
  try {
    PackageInfo info = packageManager.getPackageInfo(packageName, 0);
    Field field = PackageInfo.class.getField("firstInstallTime");
    long timestamp = field.getLong(info);
    return new Date(timestamp);
  } catch (NameNotFoundException e) {        
    return null; // package not found
  } catch (IllegalAccessException e) {
  } catch (NoSuchFieldException e) {
  } catch (IllegalArgumentException e) {
  } catch (SecurityException e) {
  }
  // field wasn't found
  return null;
}

private Date firstNonNull(Date... dates) {
  for (Date date : dates)
    if (date != null)
      return date;
  return null;
}