Android EditText观察器按API调用时间限制？

Question

我有一个Edit text，用来观察自动更新搜索页面的变化。每输入一个字符，观察器就会被启动，所以对于一个搜索查询，如 apple，查询的方式为：。

D/debug: a
D/debug: ap
D/debug: app
D/debug: appl
D/debug: apple

所以我加了一个延迟的 2s 与定时器，和日志看起来像

D/debug: apple
D/debug: apple
D/debug: apple
D/debug: apple
D/debug: apple

连珠炮 2s. 这是我的文字观察器。

search_et.addTextChangedListener( object: TextWatcher{
    override fun afterTextChanged(s: Editable?) {
        val timer = Timer()
        timer.schedule(object : TimerTask() {
            override fun run() {
                Log.d("debug", "$s");
            }
        }, 2000)            
    }
    override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {}
    override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {}
})

我想完成的是 在2秒内从EditText中获取一次数值。，这种情况下我该怎么做才对？

Answer 1

使用处理程序的概念，我们可以这样做。通过这种方式，我们可以限制api调用的次数，同时在编辑文本中实现搜索功能。

Java.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET.NET:

        private Handler textSearchHandler  = new Handler(); //declare it as a global variable
        et_FilterStopsFromListActivity_FilterETxt.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                textSearchHandler.removeCallbacksAndMessages(null); //It will clear all previous callbacks
            }

            @Override
            public void afterTextChanged(final Editable s) {
                textSearchHandler.postDelayed(new Runnable() {
                    @Override
                    public void run() {
                       callApi();//do whatever you want to do
                        }
                    }
                }, 2000);

            }
        });

Kotlin:

private var textChangedHandler = Handler() // declare it globally.
tie_password.addTextChangedListener(object : TextWatcher {
        override fun afterTextChanged(editable: Editable?) {
            textChangedHandler.postDelayed(runnable,2000)
        }

        override fun beforeTextChanged(s: CharSequence, start: Int, count: Int, after: Int) {

        }

        override fun onTextChanged(s: CharSequence, start: Int, before: Int, count: Int) {
            textChangedHandler.removeCallbacksAndMessages(runnable)
        }
    })

 var runnable = Runnable {
    callApi() //do whatever you want to do here.
}

Answer 2

你需要为这个用例使用一个处理程序。你没有处理以前的查询结果，你必须丢弃以前的结果并发出一个新的查询。

private var runnable: Runnable? = null

private var handler: Handler? = null

private var timeToWait = 2000L //change this one for delay (time in milli)

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_search)
    setListenersForSearch()
}

private fun setListenersForSearch() {

    //Initialize your handler
    handler = Handler()

    etSearch.addTextChangedListener(object : TextWatcher {
        override fun afterTextChanged(s: Editable?) {
            runnable = Runnable {

                //check if it is not empty then search
                if (etSearch.text.toString().isEmpty().not()) {
                    search(etSearch.text.toString())
                }
            }
            handler?.postDelayed(runnable, timeToWait)
        }

        override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {

        }

        override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
            //remove call back for old query
            handler?.removeCallbacks(runnable)
        }
    })
}


private fun search(query: String) {
    //hit your API call
}