失效问题

AppBarLayout: onOffsetChanged stops being called after multiple scrolls

问题描述:

Using the CheeseSquare demo, if you register with AppBarLayout as an OnOffsetChangedListener, then onOffsetChanged is only called for a limited time. After multiple scrolls up and down, the method is never called.

• Expected - onOffsetChanged should be called consistently for all registered listeners whenever the offset of AppBarLayout changes.

• To reproduce: include this method in CheeseDetailActivity:

  @Override 
  protected void onStart() { 
  (); 
  AppBarLayout appBarLayout = (AppBarLayout) findViewById(); 
  (new () { 
  @Override 
  public void onOffsetChanged(AppBarLayout appBarLayout, int verticalOffset) { 
  (“CheeseDetailActivity”, ” verticalOffset ” + verticalOffset);

      }
  });
  

  }

原因: 
Your problem is that AppBarLayout uses WeakReference to keep track of the offsetChanged listeners, and as soon as a GC is due your listener is collected.

解决方式:

@Override
    protected void onStart() {
        ();
        AppBarLayout appBarLayout = (AppBarLayout) findViewById();
        (this);
    }

Then have CheesDetailActivity implement 

.

我在项目中是这样处理的:

@Override
    protected void onResume() {
        ();
        (this);
    }

    @Override
    protected void onPause() {
        ();
        (this);
    }

当然activity需要

implements