Android TextWatcher内容监听死循环案例详解

TextWatcher如何避免在afterTextChanged中调用setText后导致死循环,今天在用TextView时,添加了addTextChangedListener方法监听内容改变,在afterTextChanged方法中又执行了setText方法,结果造成afterTextChanged方法再次调用,然后setText,因此造成了死循环的问题。列出此问题,以备后忘。

先贴Google文档原文说明:

/** * This method is called to notify you that, somewhere within * <code>s</code>, the text has been changed. * It is legitimate to make further changes to <code>s</code> from * this callback, but be careful not to get yourself into an infinite * loop, because any changes you make will cause this method to be * called again recursively. * (You are not told where the change took place because other * afterTextChanged() methods may already have made other changes * and invalidated the offsets. But if you need to know here, * you can use {@link Spannable#setSpan} in {@link #onTextChanged} * to mark your place and then look up from here where the span * ended up. */public void afterTextChanged(Editable s);

根据文档说明意思就是调用setText之前暂时去掉此监听器, 然后再恢复添加自身即可.

如下:

xxxEdit.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) {}

@Override

public void afterTextChanged(Editable s) {

xxxEdit.removeTextChangedListener(this);

xxxEdit.setText("新取值");

xxxEdit.addTextChangedListener(this);

}

});

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