android UI-EditText的长度监听慎用TextWatcher

 1         // 昵称最多为8个字符
 2         mUsernameEditText.addTextChangedListener(new TextWatcher() {
 3             private CharSequence temp;
 4             private int editStart;
 5             private int editEnd;
 6 
 7             @Override
 8             public void beforeTextChanged(CharSequence s, int arg1, int arg2, int arg3) {
 9                 temp = s;
10             }
11 
12             @Override
13             public void onTextChanged(CharSequence s, int arg1, int arg2, int arg3) {
14             }
15 
16             @Override
17             public void afterTextChanged(Editable s) {
18                 editStart = mUsernameEditText.getSelectionStart();
19                 editEnd = mUsernameEditText.getSelectionEnd();
20                 if (temp.length() > 8) {
21                     s.delete(Math.max(editStart - 1, 0), editEnd);
22                     showToast("昵称最多为8个字符");
23                     int tempSelection = editStart;
24                     mUsernameEditText.setText(s);
25                     mUsernameEditText.setSelection(s.length());
26                 }
27             }
28         });