我有一个类似于"ali123hgj"的字符串。我想要把其中的123转换成整数。在Java中该怎么做?
int i = Integer.parseInt("blah123yeah4yeah".replaceAll("\\D", ""));
// i == 1234
请注意,这将把来自字符串不同部分的数字“合并”成一个数字。如果您只有一个数字,那么这仍然有效。如果您只想要第一个数字,那么您可以像这样做:
int i = Integer.parseInt("x-42x100x".replaceAll("^\\D*?(-?\\d+).*$", "$1"));
// i == -42
正则表达式比较复杂,但基本上它会用第一个包含数字序列(带可选的减号)来替换整个字符串,然后使用Integer.parseInt
将其解析为整数。
\d+
由:
final Pattern pattern = Pattern.compile("\\d+"); // the regex
final Matcher matcher = pattern.matcher("ali123hgj"); // your string
final ArrayList<Integer> ints = new ArrayList<Integer>(); // results
while (matcher.find()) { // for each match
ints.add(Integer.parseInt(matcher.group())); // convert to int
}
String alphanumeric = "12ABC34def";
String digits = CharMatcher.JAVA_DIGIT.retainFrom(alphanumeric); // 1234
String letters = CharMatcher.JAVA_LETTER.retainFrom(alphanumeric); // ABCdef
String digits = CharMatcher.inRange('0', '9').retainFrom(alphanumeric); // 1234
String letters = CharMatcher.inRange('a', 'z')
.or(inRange('A', 'Z')).retainFrom(alphanumeric); // ABCdef
int index = -1;
for (int i = 0; i < str.length(); i++) {
if (Character.isDigit(str.charAt(i)) {
index = i; // found a digit
break;
}
}
if (index >= 0) {
int value = String.parseInt(str.substring(index)); // parseInt ignores anything after the number
} else {
// doesn't contain int...
}
public static final List<Integer> scanIntegers2(final String source) {
final ArrayList<Integer> result = new ArrayList<Integer>();
// in real life define this as a static member of the class.
// defining integers -123, 12 etc as matches.
final Pattern integerPattern = Pattern.compile("(\\-?\\d+)");
final Matcher matched = integerPattern.matcher(source);
while (matched.find()) {
result.add(Integer.valueOf(matched.group()));
}
return result;
输入 "asg123d ddhd-2222-33sds --- ---222 ss---33dd 234" 的结果是 [123, -2222, -33, -222, -33, 234]
你可以按照以下方式来完成:
Pattern pattern = Pattern.compile("[^0-9]*([0-9]*)[^0-9]*");
Matcher matcher = pattern.matcher("ali123hgj");
boolean matchFound = matcher.find();
if (matchFound) {
System.out.println(Integer.parseInt(matcher.group(0)));
}
它也很容易适应多个数字组。这段代码仅供参考:尚未经过测试。