Handler弱引用举例（ViewPager的自动播放）

￡神魔★判官ぃ 2022-07-28 01:21 117阅读 0赞

前提该代码在HomeFragment中完成：

private int page = 0;
    
        //Handler的弱引用
        private static class MyHandler extends Handler { 
            private WeakReference<HomeFragment> weakReference;
    
            public MyHandler(HomeFragment fragment) {
                weakReference = new WeakReference<>(fragment);
            }
    
            @Override
            public void handleMessage(Message msg) {
                super.handleMessage(msg);
                HomeFragment fragment = weakReference.get();
                if (null != fragment) {
                    if (msg.what == 0) {
                        fragment.viewPager.setCurrentItem(fragment.page % fragment.list.size());
                    }
                }
            }
        }
    
        private MyHandler myHandler = new MyHandler(this);

private boolean flag = true;//用于自动播放循环条件，一直true，销毁方法里改为false
    
        //viewPager自动播放
        private void autoBanner() {
            new Thread(new Runnable() {
                @Override
                public void run() {
                    while (flag) {
                        try {
                            Thread.sleep(2500);
                            page++;
                            myHandler.sendEmptyMessage(0);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                }
            }).start();
        }
    
        @Override
        public void onDestroy() {
            super.onDestroy();
            flag = false;
        }