publicclassStringUtils{publicstaticintcountOccurrences(Stringstr,Stringsub){if(str==null||sub==null||sub.isEmpty()||str.isEmpty()){return0;}intcount=0;intindex=0;// 使用 indexOf 方法查找 sub 在 str 中的每次出现while((index=str.indexOf(sub,index))!=-1){count++;index+=sub.length();...
String s1 = "Hello"; // String literal String s2 = "Hello"; // String literal String s3 = s1; // same reference String s4 = new String("Hello"); // String object String s5 = new String("Hello"); // String object 我们使用以下图片说明来解释它: Java已经提供了一个特殊的机制,来保...
Example 1: Java String replaceAll() classMain{publicstaticvoidmain(String[] args){ String str1 ="aabbaaac"; String str2 ="Learn223Java55@";// regex for sequence of digitsString regex ="\\d+";// all occurrences of "aa" is replaceAll with "zz" System.out.println(str1.replaceAll("aa...
Assert.hasLength(String text,"text must be specified")-字符不为null且字符长度不为0Assert.hasText(String text,"text must not be empty")-text 不为null且必须至少包含一个非空格的字符 Assert.isInstanceOf(Class clazz,Object obj,"clazz must be of type [clazz]")-obj必须能被正确造型成为clazz 指定...
3. Replace All Occurrences of a Substring The following Java program replaces all occurrences of the substring “Hello” with the new String “Hi”. Stringmessage="Hello world !!";Assertions.assertEquals("Hi world !!",message.replace("Hello","Hi")); ...
"collection must not be empty")//集合非空Assert.hasLength(String text,"text must be specified")//字符不为null且字符长度不为0Assert.hasText(String text,"text must not be empty")//text 不为null且必须至少包含一个非空格的字符Assert.isInstanceOf(Class clazz, Object obj,"clazz must be of ...
1.2.5、字符串聚合操作(String Aggregation Operators) 范例 假如有一个集合 mycol { "_id" : 1, "city" : "Berkeley, CA", "qty" : 648 } { "_id" : 2, "city" : "Bend, OR", "qty" : 491 } { "_id" : 3, "city" : "Kensington, CA", "qty" : 233 } ...
Returns a new string resulting from replacing all occurrences of oldChar in this string with newChar. String String.toLowerCase(Locale locale) Converts all of the characters in this String to lower case using the rules of the given Locale. String String.toLowerCase() Converts all of the...
Matcher Method Equivalents injava.lang.String For convenience, theStringclass mimics a couple ofMatchermethods as well: public String replaceFirst(String regex, String replacement): Replaces the first substring of this string that matches the given regular expression with the given replacement. An invo...
public static void main(String[] args) { String text = "AABCCAAADCBBAADBBC"; String str = "AA"; int count = StringUtils.countMatches(text, str); System.out.println(count); } } Download Code Output: 3 That’s all about finding the occurrences of a substring in a string in Java. ...