1、 精确获取屏幕尺寸（例如：3.5、4.0、5.0寸屏幕）
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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);
}
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2、 判断是否是平板（官方用法）
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public static boolean isTablet(Context context) {
return (context.getResources().getConfiguration().screenLayout & Configuration.SCREENLAYOUT_SIZE_MASK) >=Configuration.SCREENLAYOUT_SIZE_LARGE;
}
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3、 文字根据状态更改颜色 android:textColor
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<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>
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放在res/color/目录下
4、背景色根据状态更改颜色 android:backgroup
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<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>
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如果直接给背景色color会报错。
5、 启动APK的默认Activity
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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);
}
}
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6、计算字宽
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public static float GetTextWidth(String text, float Size) {
TextPaint FontPaint = new TextPaint();
FontPaint.setTextSize(Size);
return FontPaint.measureText(text);
}
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注意如果设置了textStyle，还需要进一步设置TextPaint。
7、获取应用程序下所有Activity
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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;
}
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8、检测字符串中是否包含汉字
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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;
}
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9、检测字符串中只能包含：中文、数字、下划线(_)、横线(-)
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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();
}
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10、检查有没有应用程序来接受处理你发出的intent
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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();
}
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11、使用TransitionDrawable实现图片显示的时候有渐变效果
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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), newBitmapDrawable(mContext.getResources(), bitmap) });
//noinspection deprecation
imageView.setBackgroundDrawable(imageView.getDrawable());
imageView.setImageDrawable(td);
td.startTransition(200);
}
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比使用AlphaAnimation效果要好，可避免出现闪烁问题。
12、 扫描指定的文件
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sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, uri));
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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
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public static int dipToPX(final Context ctx, float dip) {
return (int)TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dip, ctx.getResources().getDisplayMetrics());
}
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用途：难免在Activity代码中设置位置、大小等，本方法就很有用了！
14、获取已经安装APK（列表）的路径
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PackageManager pm = getPackageManager();
for (ApplicationInfo app : pm.getInstalledApplications(0)) {
Log.d("PackageList", "package: " + app.packageName + ", sourceDir: " + app.sourceDir);
}
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输出：
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package: com.tmobile.thememanager, sourceDir: /system/app/ThemeManager.apk
package: com.touchtype.swiftkey, sourceDir: /data/app/com.touchtype.swiftkey-1.apk
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15、 多进程Preferences数据共享
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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);
}
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16、泛型ArrayList转数组
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@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()));
}
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17、 保存恢复ListView当前位置
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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);
}
}
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18、调用 便携式热点和数据共享 设置
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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;
}
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19、 格式化输出IP地址
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public static String getIp(Context ctx) {
return Formatter.formatIpAddress((WifiManager)ctx.getSystemService(Context.WIFI_SERVICE).getConnectionInfo().getIpAddress());
}
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20、 ip地址转成8位十六进制串
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/** 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
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21、 文件夹排序（先文件夹排序，后文件排序）
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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());
}
}
});
}
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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：
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new TextView(this,null,R.style.text_style);
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但你运行这代码你会发现毫无作用！正确用法：
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new TextView(new ContextThemeWrapper(this, R.style.text_style))
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23、获取网络类型名称
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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";
}
}
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24、Android解压Zip包
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/**
* 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
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25、 从assets中读取文本和图片资源
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/** 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;
}
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26、展开、收起状态栏
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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();
}
}
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用途：可用于点击Notifacation之后收起状态栏
27、 获取状态栏高度
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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;
}
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28、ListView使用ViewHolder极简写法
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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;
}
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用法：
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@Override
public 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);
}
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用起来非常简练，将ViewHolder隐于无形。
29、 设置Activity透明
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<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>
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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
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//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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注意：切换到全屏时，底部的虚拟按键仍然是显示的。次方法可多次调用用于切换
用途：播放器界面经常会用到
转自：农民伯伯