Android开发问题汇总(二)

1.Error running app: Default Activity not found

A: 问题的原因是 AndroidManifest.xml 文件配置的有问题。正确的样例如下：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="edu.self.buildexample">

<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">

<activity android:name=".BuildExampleActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>

2. How to rename java package in Android Studio?

A:Android Studio Rename Package

3.No service of type Factory available in ProjectScopeServices

A:Change maven gradle plugin version to 1.4.1 in project build.gradle file

dependencies {
    classpath 'com.android.tools.build:gradle:2.2.2'
        classpath 'com.github.dcendents:android-maven-gradle-plugin:1.4.1'
}

ReferenceNo service of type Factory available in ProjectScopeServices

###4.Android Gradle cannot find symbol class Gson A:In my case, I just added this line:

compile 'com.google.code.gson:gson:2.7'

on my app build.gradle file.

By now 2.7 is last current available version according to: https://mvnrepository.com/artifact/com.google.code.gson/gson

Please check this repository to be sure you are using last available version.

Reference:Android Gradle cannot find symbol class Gson

###5.Gradle sync failed: The SDK Build Tools revision (19.0.0) is too low for project ‘:app’. Minimum required is 19.1.0 A:设置更新版本的Build Tools:

// Step 1
File > Project Structure ... > Modules(Select your module, eg:app) > Properties > Build Tools Version > 25.0.0

// Step 2:
Module build.gradle

android {
    ...
    buildToolsVersion "25.0.0"
    ...
} 

###6.Gradle sync failed: Could not find method android() for arguments [build_5v1bwdgcgpex8ek4ayinac3qa$_run_closure3@6518ea53] on root project ‘ActionBarDemo’ of type org.gradle.api.Project. A:Root project gradle hasn’t method android(), so remove it and setting in module gradle.

###7.Failed to resolve: junit:junit:4.12 A:It happens HTTPS is blocked by proxy, so we have to disable proxy.

// Step 1
Android Studio > Preferences... > System Settings > HTTP Proxy > No Proxy

// Step 2: Uncomment http proxy settings in gradle.properties
#systemProp.http.proxyHost=mirrors.neusoft.edu.cn
#systemProp.http.proxyPort=80

Reference:Failed to resolve: junit:junit:4.12

###7.Error:Please select Android SDK A:应用的Run 标红，打开弹出的对话底部提示error please select Android SDK.工程是从 eclipse 迁移过来的，target SDK 一开始是没安装的，安装之后标红依然没有消失。File > Project Structure… > Properties > Compile SDK Version 选择一个之前安装好的版本，工程构建之后标红消息，之后再选择刚安装的 target SDK 作为Compile SDK Version, 工程自动重新构建成功，标红消息。应该是安装 SDK 版本之后没有立即生效，连带 android.app 包都找不到。

###8.unknown attr app:popuptheme A:The reason is miss relate name space:xmlns:app=”http://schemas.android.com/apk/res-auto”

// Before
<android.support.v7.widget.Toolbar
android:id="@+id/my_toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
android:elevation="4dp"
android:theme="@style/ThemeOverlay.AppCompat.ActionBar"
app:popupTheme="@style/ThemeOverlay.AppCompat.Light"/>

// After
<android.support.v7.widget.Toolbar
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/my_toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
android:elevation="4dp"
android:theme="@style/ThemeOverlay.AppCompat.ActionBar"
app:popupTheme="@style/ThemeOverlay.AppCompat.Light"/>

###9.How to get Activity’s content view? A:

this.getWindow().getDecorView().findViewById(android.R.id.content)
or

this.findViewById(android.R.id.content)
or

this.findViewById(android.R.id.content).getRootView()

Reference:How to get Activity’s content view?

###10.Conversion to Dalvik format failed with error 1

Dx 
UNEXPECTED TOP-LEVEL EXCEPTION:
    java.lang.RuntimeException: Exception parsing classes
    at com.android.dx.command.dexer.Main.processClass(Main.java:752)
    at com.android.dx.command.dexer.Main.processFileBytes(Main.java:718)
    at com.android.dx.command.dexer.Main.access$1200(Main.java:85)
    at com.android.dx.command.dexer.Main$FileBytesConsumer.processFileBytes(Main.java:1645)
    at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:170)
    at com.android.dx.cf.direct.ClassPathOpener.processDirectory(ClassPathOpener.java:229)
    at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:158)
    at com.android.dx.cf.direct.ClassPathOpener.processDirectory(ClassPathOpener.java:229)
    at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:158)
    at com.android.dx.cf.direct.ClassPathOpener.processDirectory(ClassPathOpener.java:229)
    at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:158)
    at com.android.dx.cf.direct.ClassPathOpener.processDirectory(ClassPathOpener.java:229)
    at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:158)
    at com.android.dx.cf.direct.ClassPathOpener.processDirectory(ClassPathOpener.java:229)
    at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:158)
    at com.android.dx.cf.direct.ClassPathOpener.processDirectory(ClassPathOpener.java:229)
    at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:158)
at com.android.dx.cf.direct.ClassPathOpener.process(ClassPathOpener.java:144)
...

A:This android project dependent on serveral java projects, when I change these java project’s jre from 1.8 to 1.6, it works. The deep reason isn’t clear.

11.Make the Input Box Fill in the Screen Width

A: Setting the width to zero (0dp) improves layout performance because using “wrap_content” as the width requires the system to calculate a width that is ultimately irrelevant because the weight value requires another width calculation to fill the remaining space.

<EditText android:id="@+id/edit_message"
    android:layout_weight="1"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:hint="@string/edit_message" />

Reference:Building a Simple User Interface

12. TabHost.TabSpec is not an enclosing class.

A:TabHost.TabSpec is not static so it requires an instance of the outer class.Using TabHost’s newTabSpec method instead of new TabHost.TabSpec.

Reference:Is not an enclosing class Java

13. com.android.ide.common.process.ProcessException: Failed to execute aapt

A: The reason is buildToolsVersion doesn’t match compileSdkVersion, correct it in module gradle fix problem.

Reference:解决com.android.ide.common.process.ProcessException: Failed to execute aapt

14. What is the difference between android:gravity and android:layout_gravity?

A: The difference between android:gravity and android:layout_gravity is that android:gravity positions the contents of that view (i.e. what’s inside the view), whereas android:layout_gravity positions the view with respect to its parent (i.e. what the view is contained in).

Reference:
How to Position Views Properly in Layouts

15. Expected Resource of type ID

A:It is a editor validation error as this is not a common way to deal with ids. So if your app supporting API 17 or higher, you can call View.generateViewId as

titleView.setId(View.generateViewId());

and for API < 17

Open your project’s res/values/ folder;
Create an xml filed called ids.xml with following content:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <item name="titleId" type="id" />
    <item name="svId" type="id" />
</resources>

then in your code,

titleView.setId(R.id.titleId);

sv.setId(R.id.svId);

Reference:Android - Expected Resource of type ID