title: What the actual meaning `Caused by: java.lang.RuntimeException: view must have a tag`?
body: <p>Please inform me if knowing whats tag that wanted.</p>
  
  <p><code>Caused by: java.lang.RuntimeException: view must have a tag</code></p>
  
  <p>__BaseActivity.java</p>
  
  <pre><code>    @Override
      public void setContentView(int layoutResID) {
  
          mBinding.contentParent.removeAllViews();
          DataBindingUtil.inflate(LayoutInflater.from(this), layoutResID, mBinding.contentParent, true);
          super.setContentView(mBinding.getRoot());
      }
  </code></pre>
  
  <p>__ChildActivity.java</p>
  
  <pre><code> @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          mBinding = DataBindingUtil.setContentView(this, R.layout.my_wallet);
  }
  </code></pre>
  
  <p>ERROR logcat</p>
  
  <pre><code>java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mydev}: java.lang.RuntimeException: view must have a tag
          at &lt;more...&gt;
       Caused by: java.lang.RuntimeException: view must have a tag
          at android.databinding.DataBinderMapperImpl.getDataBinder(DataBinderMapperImpl.java:121)
  </code></pre>