You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <allpages apcontinue="JavaでHMAC-SHA256を計算する" />
  </query-continue>
  <query>
    <allpages>
      <p pageid="30" ns="0" title="Error launching Android Studio" />
      <p pageid="16" ns="0" title="HashMap" />
      <p pageid="21" ns="0" title="IntStream" />
      <p pageid="44" ns="0" title="JUnit" />
      <p pageid="35" ns="0" title="Java スレッドの同期 wait notify notifyAll" />
      <p pageid="36" ns="0" title="Java スレッドをスリープさせる方法" />
      <p pageid="52" ns="0" title="Javadoc" />
      <p pageid="19" ns="0" title="JavaからJNIでC言語プログラムを呼び出す" />
      <p pageid="13" ns="0" title="Javaで10進数を2進数と8進数と16進数に変換する方法" />
      <p pageid="31" ns="0" title="JavaでC言語のdefineの定数定義に相当するものは" />
    </allpages>
  </query>
</api>