在我的应用程序中，我想跟踪EditText. 每次用户修改EditText我要跟踪的字符时：
- 如果添加/删除了一个字符
- 添加/删除字符的索引处和
- 添加/删除了什么字符
我用TextWatcher它来实现这一点。到目前为止，我的方法一直运行良好。但最近我IndexOutOfBoundsException的生产应用程序发生了 3 次崩溃。我注意到的一件事是所有崩溃都发生在操作系统版本为 6.0.1 的 Galaxy S7 上。
我正在尝试找出一种理解和修复此崩溃的好方法。请参考下面的代码
public class EditTextMonitor extends Activity implements TextWatcher {
private EditText etInputText;
private int deleteCharIndex = -1, addCharIndex = -1;
private char deleteChar;
private boolean wasCharDeleted;
private String prevCharSeq = "";
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.mylayout);
etInputText = (EditText) findViewById(R.id.etInputText);
}
// Add TextChangedListener here to prevent call to text watcher methods upon switching
// orientation
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
etInputText.addTextChangedListener(this);
}
/*
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. It is an error to attempt to
make changes to s from this callback.
*/
@Override
public 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
are about to be replaced by new text with length after.
It is an error to attempt to make changes to s from this callback.
*/
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
// if count > after then its a char delete cause the no. of chars in 's'
// will decrease when the text change is complete.
// If count < after
// then its a char addition cause the no. of chars in 's'
// will increase when the text change is complete.
if (count > after) {
// CHARACTER DELETION
// As 'count' is no. of chars being replaced from 'start' by
// 'after' no. of chars, (start+count)-1 will be the index of the
// char that that will be deleted.
deleteCharIndex = (start + count) - 1;
deleteChar = s.charAt(deleteCharIndex);
wasCharDeleted = true;
} else if (count < after) {
// CHARACTER ADDITION
// As 'count' is no. of chars being replaced from 'start' by
// 'after' no. of chars, (start+after)-1 will will be the index of the
// char that will be added.
wasCharDeleted = false;
addCharIndex = (start + after) - 1;
} else {
// Extra call to the text changed method with no change in 's'.
// Android framework bug??
wasCharDeleted = false;
Log.d(TAG, "------EXTRA CALL TO BEFORETEXTCHANGED------");
}
}
@Override
public void afterTextChanged(Editable s) {
// Don't process if redundant call to afterTextChanged method.
// A framework bug??
if (!prevCharSeq.equals(s.toString())) {
if (wasCharDeleted) {
// handle char delete
if (deleteChar == 'x'
&& (s.length() == 0 || s.charAt(deleteCharIndex - 1) == ' ')) {
// Business logic to deal with the case where the deleted char was an independent 'x'
} else {
// Business logic to deal with the case where deleted char was anything other than an independent 'x'.
}
} else {
// handle char addition
***if (s.charAt(addCharIndex) == 'x'// CRASH OCCURS ON THIS LINE <-----------------***
&& (s.length() == 1 || s.charAt(addCharIndex - 1) == ' ')) {
// Business logic to deal with the case where added char is an independent 'x'
} else {
// Business logic to deal with the case where added char is anything other than an independent 'x'
}
}
}
prevCharSeq = s.toString();
}
}
到目前为止的 3 次崩溃是：
java.lang.IndexOutOfBoundsException: charAt: 24 >= length 23
java.lang.IndexOutOfBoundsException: charAt: 202 >= length 198
java.lang.IndexOutOfBoundsException: charAt: 1 >= length 1
查看异常中的索引，我假设addCharIndex没有正确计算。这意味着要么我对参数的理解beforeTextChanged不正确，要么TextWatcher方法没有按预期顺序调用，或者它们被多次调用并更新了参数，这弄乱了我计算addCharIndexin的逻辑beforeTextChanged。
任何有关如何解决此问题的帮助和见解将不胜感激。
谢谢。