android | 易学教程

How to keep layout unchanged when keyboard is displayed?

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问题 I have a toy example of a html app running in Cordova (code below) which is laid out with everything relative to the viewport size (either position:absolute and percent, or vh units for fonts). Unexpectedly, when a keyboard is shown, the viewport shrinks vertically resulting in the layout shown in the second screenshot. ; I would like the initial layout to be done exactly as it is here, relative to the full width/height of the viewport, but for it to not change size when the keyboard is

How to store secretKey in KeyStore and retrieve it

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问题 I'm currently developing an android application but i'm expecting some issues due to storage and retrieving of a SecretKey into the Keystore This is my code: Here I generate the SecretKey and then save it into KeyStore, and use it to encrypt my data try { KeyStore keyStore=null; keyStore= KeyStore.getInstance(KeyStore.getDefaultType()); char[] passwordKS="network".toCharArray(); SecureRandom sr = SecureRandom.getInstance("SHA1PRNG"); sr.setSeed("any data used as random seed".getBytes());

android code to detect whether my android app user is online or not

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问题 I have developed a android application, have launched it in google play. It has been downloaded by many people (around 200-300) . Now my question is i want to know if my user is online or not. Actually i want to perform a particular action in my server for that user when the user is online. How can i know the user is online and currently viewing my app screen? i have tried the below code , which can only say whether device has internet conncetion or not.. private boolean isOnline() { try {

What is proper usage of requestCellInfoUpdate()?

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问题 Utilizing onSignalStrengthsChanged , getAllCellInfo() , and related methods, my app monitors cell signal data and displays the results in realtime. My code works very well when targeting API 28 and lower, automatically refreshing the data as it changes. Targeting API 29 results in some Android 10 devices failing to update the data -- but not all. I discovered TelephonyManager.requestCellInfoUpdate() was added to API 29, which may(?) be needed to resolve this issue. However, I have been unable

Using trained Scikit-learn svm classifiers in Android [closed]

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问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 5 years ago . Improve this question I am developing an Android app that uses sensor data from the phone to classify activities. I also really prefer scikit-learn to any of the Java machine learning libraries. So I created a very minimal REST api using Django and scikit learn to train sensor

Android process memory map

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问题 I try to understand the memory regions in the com.android.browser process [memory map below], and have a few questions: For the address ranges without a pathname, what are mapped here? There're multiple [stack:xxxx] regions, are they thread local stacks? If not, what are they? They seem to get mapped in many different locations scattered in the memory space. If assuming the stack is at the top of the user space, then the user space memory is 2GB, the rest 2GB taken by the kernel space. Is it

Java多态的理解

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什么是多态面向对象的三大特性：封装、继承、多态。从一定角度来看，封装和继承几乎都是为多态而准备的。这是我们最后一个概念，也是最重要的知识点。多态的定义：指允许不同类的对象对同一消息做出响应。即同一消息可以根据发送对象的不同而采用多种不同的行为方式。（发送消息就是函数调用）。实现多态的技术称为：动态绑定（dynamic binding），是指在执行期间判断所引用对象的实际类型，根据其实际的类型调用其相应的方法。多态的作用：消除类型之间的耦合关系。现实中，关于多态的例子不胜枚举。比方说按下 F1 键这个动作，如果当前在 Flash 界面下弹出的就是 AS 3 的帮助文档；如果当前在 Word 下弹出的就是 Word 帮助；在 Windows 下弹出的就是 Windows 帮助和支持。同一个事件发生在不同的对象上会产生不同的结果。多态存在的三个必要条件 1、要有继承；2、要有重写；3、父类引用指向子类对象。上菜 public class A { public String show ( D obj ) { //方法一 return ( "A and D" ); } public String show ( A obj ) { //方法二 return ( "A and A" ); } static class B extends A { public String show

Get text from a URL using Android HttpURLConnection

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问题 how can i get the content of the URLbelow using HttpURLConnection and put it in a TextView ? http://ephemeraltech.com/demo/android_tutorial20.php 回答1: class GetData extends AsyncTask<String, Void, String> { @Override protected String doInBackground(String... params) { HttpURLConnection urlConnection = null; String result = ""; try { URL url = new URL("http://ephemeraltech.com/demo/android_tutorial20.php"); urlConnection = (HttpURLConnection) url.openConnection(); int code = urlConnection

In Android 10 devices, Biometric prompt is failing with ERROR_CANCELED all the time on top of lock screen

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问题 In Android 10 devices, Biometric prompt is failing with BiometricPrompt.ERROR_CANCELED all the time on top of the lock screen. Error is returned in onAuthenticationError callback of BiometricPrompt.AuthenticationCallback class. The biometric prompt authentication is working when the device is unlocked. is it possible to have biometric prompt authentication done on top of device lock screen in Android 10 when setDeviceCredentialAllowed is set to true? Update: The issue is only when

How check programmaticallly TEE support on Android?

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问题 How check programmaticallly TEE support on Android? In a project we need check if TEE (Trusted Execution Environment) is supported in order to make a decision. Regards. 回答1: Android 7.0 introduced this feature: Key Attestation, which gives you more confidence that the keys you use in your app are stored in a device's hardware-backed keystore. but not perfect since only a small number of devices running Android 7.0 (API level 24) support hardware-level key attestation; all other devices