Why Warning:Unable to find optional library: org.a

问题:

My gradle file:

apply plugin: 'com.android.application' 

android { 
  useLibrary 'org.apache.http.legacy' 
  compileSdkVersion 23 
  buildToolsVersion "23.0.0" 

  defaultConfig { 
    applicationId "com.skripsi.irwanto.paud" 
    minSdkVersion 15 
    targetSdkVersion 23 
    versionCode 1 
    versionName "1.0" 
  } 

  buildTypes { 
    release { 
      minifyEnabled false 
      proguardFiles getDefaultProauardFile('proguard-android.txt'), 'proguard-rules.pro' 
    } 
  } 
} 
dependencies { 
 compile fileTree(include: ['*.jar'], dir: 'libs') 
 testCompile 'junit:junit:4.12' 
 compile 'com.android.support:appcompat-v7:23.1.11 
} 

And I get Warning:Unable to find optional library: org.apache.http.legacy

回答1:

I guess, the easier way to solve this issue without having to reinstall the SDK is to create a file called optional.json in <sdk-path>\platforms\android-23\optional\ directory with the following content:

[
  {
    "name": "org.apache.http.legacy",
    "jar": "org.apache.http.legacy.jar",
    "manifest": false
  }
]

It solved the problem for me.

---

EDIT: Information taken from @domoch's answer below on how to locate your SDK location

To Locate your Android SDK's Location

Go to Android Studio Settings -> Appearence & Behavior -> System Settings and look for Android SDK Location. In Windows, it usually would be pointing to C:\Users\<username>\AppData\Local\Android\sdk.

回答2:

I had exactly the same issue. Please check if you have android-sdk-windows\platforms\android-23\optional\optional.json file in place. If not then just reinstall API 23 (remove and install again).

回答3:

Why? If you use Android Studio on Windows then optional.json file should be not only in \Program Files (x86)\...\platforms\android-23\optional\ .

So: go to Android Studio Settings -> Appearence & Behavior -> System Settings and look for Android SDK Location, copy (or create) optional.json in corresponding folder. Or just edit Android SDK Location to \Program Files (x86)\...

In my case Android SDK Location was C:\Users\Usernade\AppData\Local\Android\sdk and there was no optional.json file.

回答4:

1. Settings -> Appearence & Behavior -> System Settings and look for Android SDK Location

2. platforms/Android 23/optional/

3. org.apache.http.legacy jar file is copy and paste your android studio project lib and this jar file gradle compile files('libs/org.apache.http.legacy.jar')

回答5:

The error is that the optional.json file is not in the <sdk-path>\platforms\android-23\optional\ folder.

I solved this by the following:

1. Go to the sdk manager
2. Select Android Sdk and updates are available in the Appropriate API level.
3. Just update it.