package constxiong.interview;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* 统计一段长字符串中某字符串的出现次数
* @author ConstXiong
* @date 2019-11-13 11:01:22
*/
public class TestCountWordTimesInText {
public static void main(String[] args) {
String text = "统计一CX段长CX字符串中某字符串的出C现X次cx数";
String word = "CX";
System.out.println(countWordTimesByCutString(text, word));
System.out.println(countWordTimesByReplace(text, word));
System.out.println(countWordTimesByRegex(text, word));//正则匹配，需要注通配符的使用对结果的影响
}
/**
* 截取字符串统计字符串出现次数
* @param text
* @param word
* @return
*/
public static int countWordTimesByCutString(String text, String word) {
int times = 0;
if (!isEmpty(text) && !isEmpty(word)) {
String subText = text;
int index = -1;
int wordLength = word.length();
while (subText.length() >= wordLength && (index = subText.indexOf(word)) > -1) {
subText = subText.substring(index + wordLength);
times++;
}
}
return times;
}
/**
* 通过替换字符串，统计字符串出现次数
* @param text
* @param word
* @return
*/
public static int countWordTimesByReplace(String text, String word) {
int times = 0;
if (!isEmpty(text) && !isEmpty(word)) {
times = (text.length() - text.replace(word, "").length()) / word.length();
}
return times;
}
/**
* 通过正则表达式，统计字符串出现次数
* @param text
* @param word
* @return
*/
public static int countWordTimesByRegex(String text, String word) {
int times = 0;
if (!isEmpty(text) && !isEmpty(word)) {
Pattern p = Pattern.compile(word);
Matcher m = p.matcher(text);
while (m.find()) {
times++;
}
}
return times;
}
/**
* 字符串是否为空
* @param str
* @return
*/
private static boolean isEmpty(String str) {
return str == null || str.length() == 0;
}
}
