java.lang.ClassNotFoundException: Didn’t find class on path: dexpathlist

ref: https://stackoverflow.com/questions/22399572/java-lang-classnotfoundexception-didnt-find-class-on-path-dexpathlist?utm_medium=organic&utm_source=google_rich_qa&utm_campaign=google_rich_qa

I should understand the problem by just seeing

dex errors

But it took a half day to fix the issue.
I fix this by following android developers page’s instruction:https://developer.android.com/studio/build/multidex.html

First add this to gradle.build file :

defaultConfig {
    ...
    minSdkVersion 14
    targetSdkVersion 21
    ...

    // Enabling multidex support.
    multiDexEnabled true
}

 dependencies {
     compile 'com.android.support:multidex:1.0.0'
 }
Then extend Application class (or declare the application class in 
AndroidManifest.xml
 or override 
attachBaseContext()
 function with the 
MultiDexApplication
 class as instructed on the above link.
That’s all and it solved the problem.