Java删除字符串的第一部分（不区分大小写）

Question

I searched and couldn't find the right code as I only saw case sensitive ones.

I am writing code that checks that the file name starts with "CMF-". I have the code that if the name doesn't start with CMF- then it is added (this works).

However, I am having an issue with case-sensitivity. The first if statement is where I need help.

For example, when someone saves the name as cmf-something then I need to delete the cmf- and put CMF- in its place. As another example, someone saves a file as Cmf-something it will also need to delete the Cmf- and put CMF- in its place.

    String name = document.getObjectName();

    String newName;

    String haystack = "CMF-";
    if(haystack.regionMatches(true, 0, name, 0, 4) && !name.startsWith(haystack))
    {
        //part to delete lowercase cmf and then add cmf
    }

    //Check the object name for CMF-
    if(!haystack.regionMatches(true, 0, name, 0, 4))
    {
        //System.out.println("Missing CMF- on name \nAdding CMF- to " + name);

        StringBuffer str = new StringBuffer("CMF-");
        newName = str.append(name).toString();

        document.setObjectName(newName);
    }

Answer 1

If I understand your question correct, just make it lowercase and check

if(newString.toLowerCase().starstWith("cmf")){
  newString = newString.substring(3);
}

Answer 2

Your approach seems overly complicated. Why not do something like:

String name = document.getObjectName();
//Check for names starting "CMF-", "cmf-", "Cmf-", etc.
if (name.substring(0,4).equalsIgnoreCase("CMF-")){
    name = "CMF-"+name.substring(4); //May even overwrite correct name.
} else {
    name = "CMF-" + name;
}

And you can also include some error checking for names that would be too short and cause out of bounds exceptions.

Answer 3

I like Lars Nielsen solution for it's simplicity, but if you would like to see how regular expression will look in such case, here it is:

"Cmf-abc".matches("(?i)^cmf-.*"); // true

Test .

Regular expression (?i)^cmf-.* works like this:

• (?i) enables case insensitive-matching (by default it is case-sensitive).
• ^cmf- means that we want to have cmf- (or Cmf- , CMF- , ...) in the beggining of the string...
• .* - ...followed with whatever.