android - onTextChanged 与 Android 中的 afterTextChanged - 需要现场示例

Question

我正在阅读有关 Android 编程的 TextWatcher。我无法理解 afterTextChanged() 和 onTextChanged() 之间的区别。

虽然我提到 Differences between TextWatcher 's onTextChanged, beforeTextChanged and afterTextChanged ，我仍然无法想到需要使用 onTextChanged() 而不是 afterTextChanged() 的情况。

Answer 1

我在 Android Dev Portal 上找到了对此的解释

http://developer.android.com/reference/android/text/TextWatcher.html

**abstract void afterTextChanged(Editable s)**
This method is called to notify you that, somewhere within s, the text has been changed.

**abstract void beforeTextChanged(CharSequence s, int start, int count, int after)**
This method is called to notify you that, within s, the count characters beginning at start are about to be replaced by new text with length after.

**abstract void onTextChanged(CharSequence s, int start, int before, int count)**
This method is called to notify you that, within s, the count characters beginning at start have just replaced old text that had length before.

所以，两者的区别是:

• 我可以使用afterTextChanged更改我的文本，而onTextChanged不允许我这样做
• onTextChanged 给我更改位置的偏移量，而 afterTextChanged 没有