1.关于Handler延时处理机制:

    mHandler = new Handler();
        mHandler.postDelayed(new Runnable() {
            @Override
            public void run() {
                Intent intent = new Intent(HandlerActivity.this,ButtonActivity.class);
                startActivity(intent);
            }
        },3000);

2.handler线程间的通信

 mHandler = new Handler(){
            @Override
            public void handleMessage(@NonNull Message msg) {
                super.handleMessage(msg);
                switch (msg.what){
                    case 1:
                        ToastUtil.showMsg(HandlerActivity.this,"线程通信成功");
                        break;
                }
            }
        };
//开启子线程
        new Thread(){
            @Override
            public void run() {
                super.run();
                Message msg = new Message();
                msg.what=1;
                mHandler.sendMessage(msg);
            }
        }.start();