List-ArrayList 使用

今天优化一段代码，如下

int num = 0; 
            boolean skipAppend = false;
            int types_ext1[] = new int[] {
                    ModuleType.TYPE_CONTACT, ModuleType.TYPE_MESSAGE,
                    ModuleType.TYPE_PICTURE, ModuleType.TYPE_BOOKMARK,ModuleType.TYPE_MUSIC
            };   
            int types_ext2[] = new int[] {
                    ModuleType.TYPE_CONTACT, ModuleType.TYPE_MESSAGE,
                    ModuleType.TYPE_PICTURE, ModuleType.TYPE_BOOKMARK,ModuleType.TYPE_CALENDAR
            };
            int types_ext3[] = new int[] {
                    ModuleType.TYPE_CONTACT, ModuleType.TYPE_MESSAGE,
                    ModuleType.TYPE_PICTURE, ModuleType.TYPE_BOOKMARK
            };
if(mIsGoogleOrigCalendarExist && mIsGoogleOrigMusicExist){
            num = types.length;
            for (int i = 0; i < num; i++) {
                types_ext[i] = types[i] ;
            }
            MyLogger.logE("yjp", "music & calendar are not 3rd-party");
        } else if(!(mIsGoogleOrigCalendarExist || mIsGoogleOrigMusicExist)){
            num = types_ext3.length;
            for (int i = 0; i < num; i++) {
                types_ext[i] = types_ext3[i];
            }
            MyLogger.logE("yjp", "music & calendar are 3rd-party");
        } else if(!mIsGoogleOrigCalendarExist && mIsGoogleOrigMusicExist){
            num = types_ext1.length;
            for (int i = 0; i < num; i++) {
                types_ext[i] = types_ext1[i];
            }
            MyLogger.logE("yjp", "calendar is 3rd-party");
        } else if(mIsGoogleOrigCalendarExist && !mIsGoogleOrigMusicExist){
            num = types_ext2.length;
            for (int i = 0; i < num; i++) {
                types_ext[i] = types_ext2[i];
            }
            MyLogger.logE("yjp", "music is  3rd-party");
        }

这段代码，其实就是改变int[]里面的元素。因为int[]数组就是增删比较麻烦，只能靠循环提取到另外的数组。所以，我想到了使用list，这样动态改变起来就非常的方便

如下

 ArrayList<Integer> typeList  = new ArrayList<Integer>();
            for (int i = 0; i < types.length; i++) {
                typeList.add(types[i]);
            }    
            try {
                 PackageManager pm1 = getPackageManager();
                 pm1.getPackageInfo("com.android.calendar", PackageManager.GET_ACTIVITIES);
                 mIsGoogleOrigCalendarExist = true;
             } catch (PackageManager.NameNotFoundException e) { 
                        MyLogger.logE("yjp", "google original Calendar not found");
             }    
            try {
                 PackageManager pm2 = getPackageManager();
                 pm2.getPackageInfo("com.android.music", PackageManager.GET_ACTIVITIES);
                 mIsGoogleOrigMusicExist = true;
             } catch (PackageManager.NameNotFoundException e) { 
                        MyLogger.logE("yjp", "google original Music not found");
             }    
            if (!mIsGoogleOrigMusicExist) {
                typeList.remove(Integer.valueOf(ModuleType.TYPE_MUSIC));
            }    
            if (!mIsGoogleOrigCalendarExist) {
                typeList.remove(Integer.valueOf(ModuleType.TYPE_CALENDAR));
            }    
            if (FeatureOption.VANZO_OOS_BROWSER_SUPPORT) {
                typeList.remove(Integer.valueOf(ModuleType.TYPE_BOOKMARK));
            }    
            int num = typeList.size();

 在修改的时候，遇到了一个问题，就是当我尝试移除一个名为ModuleType.TYPE_BOOKMARK的元素的时候，我使用的方法是typeList.remove(ModuleType.TYPE_BOOKMARK);结果一直报错，说是数组越界。这个是很容易理解的，因为 ModuleType.TYPE_BOOKMARK本身就是一个数值，代码这时候认为你是移除这个位置上的元素。后来改为这个方法，成功了。另外，这个代码中有一点还是非常值得我们学习的。就是

 try {
                 PackageManager pm1 = getPackageManager();
                 pm1.getPackageInfo("com.android.calendar", PackageManager.GET_ACTIVITIES);
                 mIsGoogleOrigCalendarExist = true;
             } catch (PackageManager.NameNotFoundException e) { 
                        MyLogger.logE("yjp", "google original Calendar not found");
             }    

它巧妙的运用了异常以后，对接下来try{}代码不做处理的特点，更改了标志位的状态