Java字符串常用方法

1.判空

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-lang3</artifactId>
</dependency>

// null-safe method
StringUtils.isEmpty(string)   
StringUtils.isBlank(string) 

2. 去除最后一个字符

// not null-safe
String TEST_STRING = "abcdef";

StringUtils.substring(TEST_STRING, 0, TEST_STRING.length() - 1);

//null-safe
StringUtils.chop(TEST_STRING);

3.统计字符出现的次数

Let's use streams and lambdas to implement the count:

String someString = "elephant";
long count = someString.chars().filter(ch -> ch == 'e').count();
assertEquals(2, count);

long count2 = someString.codePoints().filter(ch -> ch == 'e').count();
assertEquals(2, count2);

Using StringUtils

int count = StringUtils.countMatches("elephant", "e");
assertEquals(2, count);

4.分割

 Sring原生方法

not null-safe
String[] splitted = "192.168.1.178".split("\\.")

StringUtils.split()

String[] splitted = StringUtils.split("car jeep scooter", " ");

5.字符串比较

// 原生
Objects.equals()
// StringUtils
StringUtils.equals()
StringUtils.equalsIgnoreCase()

 

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