1、 精确获取屏幕尺寸（例如：3.5、4.0、5.0寸屏幕）

public static double getScreenPhysicalSize(Activity ctx) {      DisplayMetrics dm = new DisplayMetrics();      ctx.getWindowManager().getDefaultDisplay().getMetrics(dm);      double diagonalPixels = Math.sqrt(Math.pow(dm.widthPixels, 2) + Math.pow(dm.heightPixels, 2));      return diagonalPixels / (160 * dm.density);}

2、 判断是否是平板（官方用法）

public static boolean isTablet(Context context) {     return (context.getResources().getConfiguration().screenLayout & Configuration.SCREENLAYOUT_SIZE_MASK) >= Configuration.SCREENLAYOUT_SIZE_LARGE;

public static float GetTextWidth(String text, float Size) {     TextPaint FontPaint = new TextPaint();     FontPaint.setTextSize(Size);     return FontPaint.measureText(text);}

 }

3、 文字根据状态更改颜色android:textColor

<selector xmlns:android="http://schemas.android.com/apk/res/android">      <item android:color="#53c1bd" android:state_selected="true"/>      <item android:color="#53c1bd" android:state_focused="true"/>      <item android:color="#53c1bd" android:state_pressed="true"/>      <item android:color="#777777"/></selector>

4、背景色根据状态更改颜色 android:backgroup

<selector xmlns:android="http://schemas.android.com/apk/res/android">    <item android:state_selected="true">         <shape>             <gradient                   android:angle="0"                   android:centerColor="#00a59f"                   android:endColor="#00a59f"                   android:startColor="#00a59f" />         </shape>    </item>    <item android:state_focused="true">         <shape>              <gradient                   android:angle="0"                   android:centerColor="#00a59f"                   android:endColor="#00a59f"                   android:startColor="#00a59f" />         </shape>     </item>     <item android:state_pressed="true">         <shape>              <gradient                   android:angle="0"                   android:centerColor="#00a59f"                   android:endColor="#00a59f"                   android:startColor="#00a59f" />          </shape>      </item>      <item>          <shape>              <gradient                  android:angle="0"                  android:centerColor="#00ff00"                  android:endColor="00ff00"                  android:startColor="00ff00" />          </shape>      </item> </selector>

5、 启动APK的默认Activity

public static void startApkActivity(final Context ctx, String packageName) {     PackageManager pm = ctx.getPackageManager();     PackageInfo pi;     try {          pi = pm.getPackageInfo(packageName, 0);          Intent intent = new Intent(Intent.ACTION_MAIN, null);          intent.addCategory(Intent.CATEGORY_LAUNCHER);          intent.setPackage(pi.packageName);List<ResolveInfo> apps = pm.queryIntentActivities(intent, 0);           ResolveInfo ri = apps.iterator().next();          if (ri != null) {                String className = ri.activityInfo.name;                intent.setComponent(new ComponentName(packageName, className));                ctx.startActivity(intent);          }     } catch (NameNotFoundException e) {          Log.e("startActivity", e);     }}

6、计算字宽

public static float GetTextWidth(String text, float Size) {     TextPaint FontPaint = new TextPaint();     FontPaint.setTextSize(Size);     return FontPaint.measureText(text);}

7、获取应用程序下所有Activity

public static ArrayList<String> getActivities(Context ctx) {      ArrayList<String> result = new ArrayList<String>();      Intent intent = new Intent(Intent.ACTION_MAIN, null);      intent.setPackage(ctx.getPackageName());      for (ResolveInfo info : ctx.getPackageManager().queryIntentActivities(intent, 0)) {           result.add(info.activityInfo.name);      }      return result;}

8、检测字符串中是否包含汉字

public static boolean checkChinese(String sequence) {     final String format = "[\\u4E00-\\u9FA5\\uF900-\\uFA2D]";     boolean result = false;     Pattern pattern = Pattern.compile(format);     Matcher matcher = pattern.matcher(sequence);     result = matcher.find();     return result;}

9、检测字符串中只能包含：中文、数字、下划线(_)、横线(-)

public static boolean checkNickname(String sequence) {     final String format = "[^\\u4E00-\\u9FA5\\uF900-\\uFA2D\\w-_]";     Pattern pattern = Pattern.compile(format);     Matcher matcher = pattern.matcher(sequence);     return !matcher.find();}

10、检查有没有应用程序来接受处理你发出的intent

public static boolean isIntentAvailable(Context context, String action) {    final PackageManager packageManager = context.getPackageManager();    final Intent intent = new Intent(action);    List<ResolveInfo> list = packageManager.queryIntentActivities(intent, PackageManager.MATCH_DEFAULT_ONLY);    return list.size();}

11、使用TransitionDrawable实现图片显示的时候有渐变效果

private void setImageBitmap(ImageView imageView, Bitmap bitmap) {      // Use TransitionDrawable to fade in.      final TransitionDrawable td = new TransitionDrawable(new Drawable[] { new ColorDrawable(android.R.color.transparent), new BitmapDrawable(mContext.getResources(), bitmap) });      //noinspection deprecation      imageView.setBackgroundDrawable(imageView.getDrawable());      imageView.setImageDrawable(td);      td.startTransition(200);}

12、 扫描指定的文件

sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, uri));

用途：从本软件新增、修改、删除图片、文件某一个文件（音频、视频）需要更新系统媒体库时使用，不必扫描整个SD卡。

13、Dip转px

public static int dipToPX(final Context ctx, float dip) {      return (int)TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dip, ctx.getResources().getDisplayMetrics()); }

14、获取已经安装APK（列表）的路径

PackageManager pm = getPackageManager();for (ApplicationInfo app : pm.getInstalledApplications(0)) {      Log.d("PackageList", "package: " + app.packageName + ", sourceDir: " + app.sourceDir);}

15、 多进程Preferences数据共享

public static void putStringProcess(Context ctx, String key, String value) {     SharedPreferences sharedPreferences = ctx.getSharedPreferences("preference_mu", Context.MODE_MULTI_PROCESS);     Editor editor = sharedPreferences.edit();     editor.putString(key, value);     editor.commit();}public static String getStringProcess(Context ctx, String key, String defValue) {     SharedPreferences sharedPreferences = ctx.getSharedPreferences("preference_mu", Context.MODE_MULTI_PROCESS);     return sharedPreferences.getString(key, defValue);}

16、泛型ArrayList转数组

@SuppressWarnings("unchecked")public static <T> T[] toArray(Class<?> cls, ArrayList<T> items) {     if (items == null || items.size() == 0) {          return (T[]) Array.newInstance(cls, 0);     }     return items.toArray((T[]) Array.newInstance(cls, items.size()));}

17、 保存恢复ListView当前位置

private void saveCurrentPosition() {      if (mListView != null) {            int position = mListView.getFirstVisiblePosition();            View v = mListView.getChildAt(0);            int top = (v == null) ? 0 : v.getTop();            //保存position和top       }}private void restorePosition() {       if (mFolder != null && mListView != null) {             int position = 0;//取出保存的数据             int top = 0;//取出保存的数据             mListView.setSelectionFromTop(position, top);       }}

18、调用便携式热点和数据共享设置

public static Intent getHotspotSetting() {     Intent intent = new Intent();     intent.setAction(Intent.ACTION_MAIN);     ComponentName com = new ComponentName("com.android.settings", "com.android.settings.TetherSettings");     intent.setComponent(com);     return intent;}

19、 格式化输出IP地址

public static String getIp(Context ctx) {      return Formatter.formatIpAddress((WifiManager) ctx.getSystemService(Context.WIFI_SERVICE).getConnectionInfo().getIpAddress()); }

20、 ip地址转成8位十六进制串

/** ip转16进制 */public static String ipToHex(String ips) {     StringBuffer result = new StringBuffer();     if (ips != null) {          StringTokenizer st = new StringTokenizer(ips, ".");          while (st.hasMoreTokens()) {                String token = Integer.toHexString(Integer.parseInt(st.nextToken()));                if (token.length() == 1)                      token = "0" + token;                result.append(token);          }     }     return result.toString();} /** 16进制转ip */public static String texToIp(String ips) {     try {          StringBuffer result = new StringBuffer();          if (ips != null && ips.length() == 8) {               for (int i = 0; i < 8; i += 2) {                    if (i != 0)                          result.append('.');                    result.append(Integer.parseInt(ips.substring(i, i + 2), 16));               }          }          return result.toString();     } catch (NumberFormatException ex) {          Logger.e(ex);     }     return "";} ip:192.168.68.128 16 =>hex :c0a84480

21、 文件夹排序（先文件夹排序，后文件排序）

public static void sortFiles(File[] files) {     Arrays.sort(files, new Comparator<File>() {          @Override          public int compare(File lhs, File rhs) {               //返回负数表示o1 小于o2，返回0 表示o1和o2相等，返回正数表示o1大于o2。               boolean l1 = lhs.isDirectory();               boolean l2 = rhs.isDirectory();               if (l1 && !l2)                    return -1;               else if (!l1 && l2)                    return 1;               else {                    return lhs.getName().compareTo(rhs.getName());               }          }     });}

22、代码设置TextView的样式

使用过自定义Dialog可能马上会想到用如下代码：

new TextView(this,null,R.style.text_style);

但你运行这代码你会发现毫无作用！正确用法：

new TextView(new ContextThemeWrapper(this, R.style.text_style))

23、获取网络类型名称

public static String getNetworkTypeName(Context context) {     if (context != null) {          ConnectivityManager connectMgr = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);          if (connectMgr != null) {                  NetworkInfo info = connectMgr.getActiveNetworkInfo();                  if (info != null) {                       switch (info.getType()) {                            case ConnectivityManager.TYPE_WIFI:                                  return "WIFI";                            case ConnectivityManager.TYPE_MOBILE:                                  return getNetworkTypeName(info.getSubtype());                       }                  }          }     }     return getNetworkTypeName(TelephonyManager.NETWORK_TYPE_UNKNOWN);} public static String getNetworkTypeName(int type) {     switch (type) {          case TelephonyManager.NETWORK_TYPE_GPRS:               return "GPRS";          case TelephonyManager.NETWORK_TYPE_EDGE:               return "EDGE";          case TelephonyManager.NETWORK_TYPE_UMTS:               return "UMTS";          case TelephonyManager.NETWORK_TYPE_HSDPA:               return "HSDPA";          case TelephonyManager.NETWORK_TYPE_HSUPA:               return "HSUPA";          case TelephonyManager.NETWORK_TYPE_HSPA:               return "HSPA";          case TelephonyManager.NETWORK_TYPE_CDMA:               return "CDMA";          case TelephonyManager.NETWORK_TYPE_EVDO_0:               return "CDMA - EvDo rev. 0";          case TelephonyManager.NETWORK_TYPE_EVDO_A:               return "CDMA - EvDo rev. A";          case TelephonyManager.NETWORK_TYPE_EVDO_B:               return "CDMA - EvDo rev. B";          case TelephonyManager.NETWORK_TYPE_1xRTT:               return "CDMA - 1xRTT";          case TelephonyManager.NETWORK_TYPE_LTE:               return "LTE";          case TelephonyManager.NETWORK_TYPE_EHRPD:               return "CDMA - eHRPD";          case TelephonyManager.NETWORK_TYPE_IDEN:               return "iDEN";          case TelephonyManager.NETWORK_TYPE_HSPAP:               return "HSPA+";          default:               return "UNKNOWN";     }}

24、Android解压Zip包

/** * 解压一个压缩文档 到指定位置 * * @param zipFileString 压缩包的名字 * @param outPathString 指定的路径 * @throws Exception */ public static void UnZipFolder(String zipFileString, String outPathString) throws Exception {      java.util.zip.ZipInputStream inZip = new java.util.zip.ZipInputStream(new java.io.FileInputStream(zipFileString));      java.util.zip.ZipEntry zipEntry;      String szName = "";while ((zipEntry = inZip.getNextEntry()) != null) {           szName = zipEntry.getName();            if (zipEntry.isDirectory()) {                 // get the folder name of the widget                szName = szName.substring(0, szName.length() - 1);                java.io.File folder = new java.io.File(outPathString + java.io.File.separator + szName);                folder.mkdirs();           } else {                 java.io.File file = new java.io.File(outPathString + java.io.File.separator + szName);                file.createNewFile();                // get the output stream of the file                java.io.FileOutputStream out = new java.io.FileOutputStream(file);                int len;                byte[] buffer = new byte[1024];                // read (len) bytes into buffer                while ((len = inZip.read(buffer)) != -1) {                      // write (len) byte from buffer at the position 0                      out.write(buffer, 0, len);                      out.flush();               }               out.close();         }    }//end of while     inZip.close(); }//end of func

25、从assets中读取文本和图片资源

/** 从assets 文件夹中读取文本数据 */public static String getTextFromAssets(final Context context, String fileName) {     String result = "";     try {          InputStream in = context.getResources().getAssets().open(fileName);          // 获取文件的字节数          int lenght = in.available();          // 创建byte数组          byte[] buffer = new byte[lenght];          // 将文件中的数据读到byte数组中          in.read(buffer);          result = EncodingUtils.getString(buffer, "UTF-8");          in.close();     } catch (Exception e) {          e.printStackTrace();     }     return result;} /** 从assets 文件夹中读取图片 */public static Drawable loadImageFromAsserts(final Context ctx, String fileName) {      try {            InputStream is = ctx.getResources().getAssets().open(fileName);            return Drawable.createFromStream(is, null);      } catch (IOException e) {            if (e != null) {                 e.printStackTrace();            }      } catch (OutOfMemoryError e) {            if (e != null) {                 e.printStackTrace();            }      } catch (Exception e) {            if (e != null) {                 e.printStackTrace();            }      }      return null;}

26、展开、收起状态栏

public static final void collapseStatusBar(Context ctx) {     Object sbservice = ctx.getSystemService("statusbar");     try {          Class<?> statusBarManager = Class.forName("android.app.StatusBarManager");          Method collapse;          if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {                collapse = statusBarManager.getMethod("collapsePanels");          } else {                collapse = statusBarManager.getMethod("collapse");          }          collapse.invoke(sbservice);     } catch (Exception e) {           e.printStackTrace();     } } public static final void expandStatusBar(Context ctx) {      Object sbservice = ctx.getSystemService("statusbar");      try {            Class<?> statusBarManager = Class.forName("android.app.StatusBarManager");            Method expand;            if (Build.VERSION.SDK_INT >= 17) {                  expand = statusBarManager.getMethod("expandNotificationsPanel");            } else {                  expand = statusBarManager.getMethod("expand");            }            expand.invoke(sbservice);      } catch (Exception e) {            e.printStackTrace();      }}

27、 获取状态栏高度

public static int getStatusBarHeight(Context context){     Class<?> c = null;     Object obj = null;     Field field = null;     int x = 0, statusBarHeight = 0;     try {          c = Class.forName("com.android.internal.R$dimen");          obj = c.newInstance();          field = c.getField("status_bar_height");          x = Integer.parseInt(field.get(obj).toString());          statusBarHeight = context.getResources().getDimensionPixelSize(x);     } catch (Exception e1) {          e1.printStackTrace();     }     return statusBarHeight;}

28、ListView使用ViewHolder极简写法

public static <T extends View> T getAdapterView(View convertView, int id) {     SparseArray<View> viewHolder = (SparseArray<View>) convertView.getTag();     if (viewHolder == null) {          viewHolder = new SparseArray<View>();          convertView.setTag(viewHolder);     }     View childView = viewHolder.get(id);     if (childView == null) {          childView = convertView.findViewById(id);          viewHolder.put(id, childView);     }     return (T) childView;}

用法：

@Overridepublic View getView(int position, View convertView, ViewGroup parent) {     if (convertView == null) {          convertView = LayoutInflater.from(getActivity()).inflate(R.layout.fragment_feed_item, parent, false);     }     ImageView thumnailView = getAdapterView(convertView, R.id.video_thumbnail);     ImageView avatarView =  getAdapterView(convertView, R.id.user_avatar);     ImageView appIconView = getAdapterView(convertView, R.id.app_icon); }

29、 设置Activity透明

<style name="TransparentActivity" parent="AppBaseTheme">      <item name="android:windowBackground">@android:color/transparent</item>      <item name="android:colorBackgroundCacheHint">@null</item>      <item name="android:windowIsTranslucent">true</item>      <item name="android:windowNoTitle">true</item>      <item name="android:windowContentOverlay">@null</item></style>

说明：AppBaseTheme一般是你application指定的android:theme是啥这里就是啥，否则Activity内部的空间风格可能不一致。

用途：用于模拟Dialog效果，比如再Service中没法用Dialog，就可以用Activity来模拟

30、 代码切换全屏

//切换到全屏getWindow().clearFlags(WindowManager.LayoutParams.FLAG_FORCE_NOT_FULLSCREEN);getActivity().getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);//切换到非全屏getWindow().clearFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);getWindow().addFlags(WindowManager.LayoutParams.FLAG_FORCE_NOT_FULLSCREEN);

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