java - ParseQuery - 正确处理 IndexOutOfBoundsException - Parse.com？

Question

如何正确处理 throwIndexOutOfBoundsException？基本上，我正在查询用户。如果用户存在，它会显示他们的个人资料。但是，如果找不到条目，​​它会使我的应用程序崩溃并引发异常。我应该在“else”语句中添加什么内容才能使应用程序不会崩溃？

                    @Override
                    public void done(List<ParseUser> parseUsers, ParseException e) {
                            if (e == null) {
                                    // The query was successful.
                                    ParseUser user = parseUsers.get(0);
                                    String userId = user.getObjectId();
                                    showProfileActivity(userId);

                            } else {
                                // The query was unsuccessful.

                            }
                        }
                    });

这是日志猫:

10-14 21:27:06.888  28595-28595/com.app.social E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.elgami.customizer, PID: 28595
    java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0
            at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:255)
            at java.util.ArrayList.get(ArrayList.java:308)
            at com.elgami.feed.SearchActivity$1$1.done(SearchActivity.java:74)
            at com.elgami.feed.SearchActivity$1$1.done(SearchActivity.java:67)
            at com.parse.Parse$6$1.run(Parse.java:944)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:148)
            at android.app.ActivityThread.main(ActivityThread.java:5417)
            at java.lang.reflect.Method.invoke(Native Method)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

Answer 1

您可以检查列表是否为空:

 @Override
      public void done(List<ParseUser> parseUsers, ParseException e) {
                                if (!parseUsers.isEmpty()) {
                                        // The query was successful.
                                        ParseUser user = parseUsers.get(0);
                                        String userId = user.getObjectId();
                                        showProfileActivity(userId);

                                } else {
                                    // The query was unsuccessful.

                                }
                            }
                        });

或者如果你想捕获异常，请使用 try -catch ，如下所示:

 @Override
  public void done(List<ParseUser> parseUsers, ParseException e) {
          if (e==null) {
            // The query was successful.
          try{
               ParseUser user = parseUsers.get(0);
               String userId = user.getObjectId();
             }
       catch(ArrayIndexOutOfBoundsException e)
           {
       // Print message for user does not exist . 
            }
             showProfileActivity(userId);
            } 
              else {
                   // The query was unsuccessful.
                     }
                       }
                            });