002-guava String operations

I. Overview

　　Providing the basic operation of the string

Second, the use

2.1, string concatenation

Guava string concatenation method is employed class Joiner

    @Test
     public  void testJdkJoin () { 
        List <String> strlist = Lists.newArrayList ( ". 1", "2", null , ". 3", ". 4" );
         // string concatenation, not Skip empty string 
        String = String.Join STR ( "," , strlist); 
        Assert.assertEquals ( "1,2,3,4" , STR); 
    } 

    @Test 
    public  void testGuavaJoin () { 
        List <String> strlist = Lists.newArrayList ( " . 1 "," 2 ", null ,". 3 ",". 4 " );
         // string concatenation, skip empty string 
        string str = Joiner.on(",").skipNulls().join(strList);on(","
        Assert.assertEquals("1,2,3,4", str);
    }

2.2 String split

    @Test
    public void testJdkSplit(){
        String str = "1,2,   3  ,,4,";
        //trimResults():去除空格，omitEmptyStrings()：删除空数组
        String[] strList = str.split(",");
        //  List<String> strList = Splitter.on(",").trimResults().omitEmptyStrings().splitToList(str);
        for (int i = 0; i < strList.length; i++) {
            String s = strList[i];
            System.out.println(s);
        }
        Assert.assertEquals(4,strList.length);
    }

    @Test
    public void testGuavaSplit () { 
        String STR = "1,2,. 3 ,,. 4," ;
         // trimResults (): removing spaces, omitEmptyStrings (): Delete empty array 
        List <String> strlist = Splitter.on ( "," ) .trimResults () omitEmptyStrings () splitToList (STR);.. 
        strList.forEach (S -> System.out.println (S)); 
        Assert.assertEquals ( . 4 , strList.size ()); 
    }

 

2.3, jdk string search method using []

    @Test
     public  void testSearch () { 
        String STR = "abcdef" ;
         // contains the string CD 
        Assert.assertEquals ( to true , str.contains ( "CD" ));
         // find the beginning of the string abc 
        Assert.assertEquals ( to true , str.startsWith ( "ABC" ));
         // Find string ending DEF 
        Assert.assertEquals ( to true , str.endsWith ( "DEF" )); 
    }

 

2.4, the string conversion

    @Test
     public  void testConversion () { 
        String STR = "abcdef" ; 
        String newStr = str.replace ( "BCDE", "Hello" ); 
        System.out.println (newStr); 
        Assert.assertEquals ( "ahellof" , newStr) ; 
        String str2 = "the ABC ABC 123" ;
         // print digital 
        System.out.println (. CharMatcher.digit () retainFrom (str2));
         // print lowercase 
        . System.out.println (CharMatcher.javaLowerCase () retainFrom (str2));
         // print capital letters 
        . System.out.println (CharMatcher.javaUpperCase () retainFrom (
         str2));// print all letters 
        System.out.println (CharMatcher.javaLetter () retainFrom (str2).);
         // replace the extra spaces into one space 
        System.out.println (CharMatcher.whitespace () trimAndCollapseFrom (str2 , '. ' ));
         // statistical letter appears 
        . System.out.println (String.valueOf (CharMatcher.javaLetter () Countin (str2))); 
    }

 

Export

ahellof
123
abc
ABC
ABCabc
ABC abc 123
6

 

 

 

 

 

 

Hair