EditText.setSelection(结束)没有效果？

我用下面的代码设置cursor在endcustomEditText(的EditText),但它带来的任何影响.

customEditText.setOnFocusChangeListener(new OnFocusChangeListener() {
            @Override
            public void onFocusChange(View v, boolean hasFocus) {
                 if (hasFocus) {
                    String customEditTextText = customEditText.getText().toString();
                    int selection = customEditTextText.length();
                    customEditText.setSelection(selection);
                }
            }
});

对此有什么想法吗？