android textutils.split以提供固定长度字符串[]

Question

我无法将一个字符串丢弃到固定的长度块中，并添加到arraylist ...下面的代码按预期迭代，但所有MessageTosplit [] up到最后一个是null。最后一个实际上有一个值。

在下面的示例中，如果返回的编辑文本，“01234567890”则“”，“和”890“。

Pattern p = Pattern.compile(".{4}");
ArrayList<String> myText = new ArrayList<String>();
String[] messageToSplit = TextUtils.split(myStringEditText.getText().toString(), p);
int x = 0;
while(x  <= (myStringEditText.getText().toString().length() / 4)) {
  Toast.makeText(getBaseContext(), x+": '" + messageToSplit[x] + "'", Toast.LENGTH_SHORT).show();
  myText.add(messageToSplit[x]);
  x++;
}

.

Answer 1

In a split operation, the regex pattern is the separator. For example, if the regex pattern were ;, then 12;34;56 would be split into 12, 34, and 56.

So in your case 01234567890 is split into "" (the string before 0123), "" (the string between 0123 and 4567) and 890 (the remainder of the string after 4567).

You probably don't want to use split but rather something like this:

Pattern p = Pattern.compile(".{1,4}");
Matcher regexMatcher = p.matcher(messageToSplit);
while (regexMatcher.find()) {
    myText.add(regexMatcher.group());
} 

.{1,4} will match 4 characters if it can, but make do with 1-3 if four are no longer available (which might happen at the end of the string if its length is not a multiple of 4).