Fragment好Activity之間的數據交換（傳值）

1、Activity把數據傳遞給Fragment

有時候從Activity跳轉到fragment時需要傳遞參數，可以使用bundle的方式傳遞

Activity中代碼

private fun initView() {
        fragments = ArrayList()
        if (fragments!!.isEmpty()) {
            fragments!!.add(MineRelationDiscoverFragment().newInstance(userId, imgUrl!!))
            fragments!!.add(MineRelationQuestionFragment().newInstance(userId, imgUrl!!))
        }
        view_pager.adapter = FragmentPagerAdapter(supportFragmentManager, fragments!!, titles)
        view_pager.offscreenPageLimit = 2
        tab.tabMode = TabLayout.MODE_FIXED
        tab.tabGravity = TabLayout.GRAVITY_FILL
        tab.run { setupWithViewPager(view_pager) }

    }

fragment中代碼

fun newInstance(userId: Int, imgUrl: String): MineRelationDiscoverFragment {
        val frag = MineRelationDiscoverFragment()
        val bundle = Bundle()
        bundle.putInt("userId", userId)
        bundle.putString("imgUrl", imgUrl)
        frag.arguments = bundle
        return frag
    }


//取參數  onViewCreated()方法中
override fun initEnv() {
        userId = arguments!!.getInt("userId")
        imgUrl = arguments!!.getString("imgUrl")
        if (!EventBus.getDefault().isRegistered(this)) {
            EventBus.getDefault().register(this)
        }
        super.initEnv()
    }

2、Fragment傳遞參數給Activity

使用接口回調的方式傳遞給Activity

Fragment代碼

 private var myListener: MineDiscoverListener? = null
    override fun onAttach(context: Context?) {
        super.onAttach(context)
        myListener = activity as MineDiscoverListener
    }


interface MineDiscoverListener {
        fun sendDiscoverIds(idList: List<Int>)
    }

參考：陳李冠

https://blog.csdn.net/chenliguan/article/details/53906934