title: Retrofit & RxJava running on JDK 7
body: <p>i'm working on API using java i'm using Retrofit2 and RxJava, first i program it for JDK 8 and now i have to change it to JDK 7, when it runs it keeps throwing this exception:</p>
  <pre><code>Exception in thread &quot;main&quot; java.lang.UnsupportedClassVersionError: retrofit2/CallAdapter$Factory : Unsupported major.minor version 52.0
  at java.lang.ClassLoader.defineClass1(Native Method)
  at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
  at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
  at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
  at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
  at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
  at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
  at java.security.AccessController.doPrivileged(Native Method)
  at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
  at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
  at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
  at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
  at networking.client.RetrofitClient.newInstance(RetrofitClient.java:14)
  at tetimer.TeCampChecker.&lt;init&gt;(TeCampChecker.java:19)
  at tetimer.TeServerTimer.scheduleTime(TeServerTimer.java:26)
  at main.Main.main(Main.java:54)
  </code></pre>
  <p>i think because RxJava adapter is using JDK 8 and converter factories i'm using, this is my code:</p>
  <pre><code>Retrofit retrofit = new Retrofit.Builder()
              .baseUrl(getBaseUrl())
              .client(okHttpClient)
              .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
              .addConverterFactory(TikXmlConverterFactory.create())
              .addConverterFactory(GsonConverterFactory.create())
              .build();
  </code></pre>
  <p>----------------------<strong>GRADLE</strong>--------------</p>
  <pre><code>def tikVersion = &quot;0.8.13&quot;
  def retrofitVersion = &quot;2.9.0&quot;
  
  compile &quot;com.squareup.retrofit2:retrofit:${retrofitVersion}&quot;
  compile &quot;com.squareup.retrofit2:converter-gson:${retrofitVersion}&quot;
  compile &quot;com.squareup.retrofit2:adapter-rxjava2:${retrofitVersion}&quot;
  compile 'com.squareup.okhttp3:logging-interceptor:4.8.1'
  
  compileOnly(&quot;com.tickaroo.tikxml:annotation:${tikVersion}&quot;)
  compile &quot;com.tickaroo.tikxml:core:${tikVersion}&quot;
  compile &quot;com.tickaroo.tikxml:retrofit-converter:${tikVersion}&quot;
  
  annotationProcessor &quot;com.tickaroo.tikxml:auto-value-tikxml:${tikVersion}&quot;
  annotationProcessor &quot;com.tickaroo.tikxml:processor:${tikVersion}&quot;
  
  compile 'io.reactivex.rxjava3:rxjava:3.0.0'
  </code></pre>
  <p>can anyone tell me what is happening and how to solve it.</p>