从任意字符串中获取最后三个字符-Java

Why not just String substr = word.substring(word.length() - 3)?

Update

Please make sure you check that the String is at least 3 characters long before calling substring():

if (word.length() == 3) {
return word;
} else if (word.length() > 3) {
return word.substring(word.length() - 3);
} else {
// whatever is appropriate in this case
throw new IllegalArgumentException("word has fewer than 3 characters!");
}

String newString = originalString.substring(originalString.length()-3);

The getChars string method does not return a value, instead it dumps its result into your buffer (or destination) array. The index parameter describes the start offset in your destination array.

Try this link for a more verbose description of the getChars method.

I agree with the others on this, I think substring would be a better way to handle what you're trying to accomplish.

You can use a substring

String word = "onetwotwoone"
int lenght = word.length(); //Note this should be function.
String numbers = word.substring(word.length() - 3);

public String getLastThree(String myString) {
if(myString.length() > 3)
return myString.substring(myString.length()-3);
else
return myString;
}

If you want the String composed of the last three characters, you can use substring(int):

String new_word = word.substring(word.length() - 3);

If you actually want them as a character array, you should write

char[] buffer = new char[3];
int length = word.length();
word.getChars(length - 3, length, buffer, 0);

The first two arguments to getChars denote the portion of the string you want to extract. The third argument is the array into which that portion will be put. And the last argument gives the position in the buffer where the operation starts.

If the string has less than three characters, you'll get an exception in either of the above cases, so you might want to check for that.

Here's some terse code that does the job using regex:

String last3 = str.replaceAll(".*?(.?.?.?)?$", "$1");

This code returns up to 3; if there are less than 3 it just returns the string.

This is how to do it safely without regex in one line:

String last3 = str == null || str.length() < 3 ?
str : str.substring(str.length() - 3);

By "safely", I mean without throwing an exception if the string is nulls or shorter than 3 characters (all the other answers are not "safe").

The above code is identical in effect to this code, if you prefer a more verbose, but potentially easier-to-read form:

String last3;
if (str == null || str.length() < 3) {
last3 = str;
} else {
last3 = str.substring(str.length() - 3);
}

I would consider right method from StringUtils class from Apache Commons Lang: http://commons.apache.org/proper/commons-lang/apidocs/org/apache/commons/lang3/StringUtils.html#right(java.lang.String,%20int)

It is safe. You will not get NullPointerException or StringIndexOutOfBoundsException.

Example usage:

StringUtils.right("abcdef", 3)

You can find more examples under the above link.

Alternative way for "insufficient string length or null" save:

String numbers = defaultValue();
try{
numbers = word.substring(word.length() - 3);
} catch(Exception e) {
System.out.println("Insufficient String length");
}

This method would be helpful :

String rightPart(String text,int length)
{
if (text.length()<length) return text;
String raw = "";
for (int i = 1; i <= length; i++) {
raw += text.toCharArray()[text.length()-i];
}
return new StringBuilder(raw).reverse().toString();
}

Here is a method I use to get the last xx of a string:

public static String takeLast(String value, int count) {
if (value == null || value.trim().length() == 0 || count < 1) {
return "";
}


if (value.length() > count) {
return value.substring(value.length() - count);
} else {
return value;
}
}

Then use it like so:

String testStr = "this is a test string";
String last1 = takeLast(testStr, 1); //Output: g
String last4 = takeLast(testStr, 4); //Output: ring

This method will return the x amount of characters from the end.

public static String lastXChars(String v, int x) {
return v.length() <= x ? v : v.substring(v.length() - x);
}

//usage

System.out.println(lastXChars("stackoverflow", 4)); // flow