Java中String中类的常用方法
Java中String中类的常用方法
1）?public?String(char?[]?value):将字符数组转成字符串；
char?c[]={‘f’,’w’,’s’,’w’,’g’,’a’};
String?s=new?String(c);
System.out.println(s);
???
??????结果为：fwswga
2）?public?String(cahr?[]?value,开始位置,新字符串的长度):将指定位置长度的字符数组转成字符串；
??????char?c[]={‘f’,’w’,’s’,’w’,’g’,’a’?}
??????String?s=new?String(c,2,2);
??????System.out.println(c);
??????结果为：sw
3)?public?String?(byte?[?]?value):将字节数组转成字符串；
??????byte?b[]={‘w’,’o’,’r’,’l’,’d’,’!’};
??????String?s=new?String(b);
??????System.out.println(s);
??????
??????结果为：world!
4)?public?String?(byte?[]?value,?开始位置，新字符串长度);将指定位置长度的字节数组转成字符串；
byte?b[]={‘w’,’o’,’r’,’l’,’d’,’!’};
String?s=new?String(b,2,3);
System.out.println(s);
?
结果为：rl
5)public?char[]?toCharArray();将字符数组转成字符串
???String?s=”Hello”;
???Char?c[]=s.toCharArray();
???for?(int?i=0;i<c.length;i++)
{?
System.out.print(c[i]+”\t”);
}
???结果为:??H e l l o
6)public?char?charAt(int?index字符下标)：返回字符串中指定位置的字符
??String?s=”Hello”;
??System.out.println(s.charAt(3));
??结果为：l
7)public?byte()?getBytes():将一个字符串转成字节数组，默认输出值为ASCII码值
???String?s=”Hello”;
byte?b[]=s.getBytes();
for?(int?i=0;i<b.length;i++)
{
??System.out.print((char)b[i]+”\t”);
}
结果为：H e l l? o
8)?public?int?length():求字符串的长度
String?s=”dwfsdfwfsadf”;
System.out.pritnln(s.length());
结果为：12
9）public?int?indexOf(String?str):从头查找指定的字符串的位置,返回值为整型，从0开始，如果没找到，则返回-1
?????String?s=”sdfwefsdgwe”;
?????System.out.println(s.indexOf(“e”));
????
?????结果为：4
10）public?int?indexOf(String?str,指定位置)；?从指定位置开始查找指定的字符串
?????String?s=”dfwfgasdfwf”;
?????System.out.println(s.indexOf(“a”,8));
?????结果为：-1
11）public?String?trim():清除字符串左右两端的空格
?????String?s=”???sdfsdfs???”;
?????System.out.println(s.trim);
?????结果为:sdfsdfs
12)?public?String?substring(int?beginindex):从指定位置到结尾截取字符串
???String?s=”fjeiflsjfowjflsdfjo”;
???System.out.println(s.substring(5));
??
???结果为：lsjfowjflsdfjo
13）public?String?substring(int?begin,int?end);指定截取字符串的开始和结束位置，不包含结束字符
???????String?s=”foweflsdfjowefjls”;
???????System.out.println(s.substring(4,9));
??????
???????结果为：flsdf
14）public?String?[]?split(String?str);按指定的字符分割字符串
???????String?s=”fwefsdfefgefaselieffs”;
???????String?ss[]=s.split(“e”);
???????for?(int?i=0;i<ss.length;i++)
???????{
???????????System.out.print(ss[i]+”\t”);
???????}
???????System.out.println();
?????
???????结果为:fw fsdf ??fg ???fas ?li ?ffs
15)?public??String??toUpperCase():将字符串全部转换成大写
??????System.out.println(new?String(“hello”).toUpperCase());
??????
??????结果为：HELLO
16）public?String?toLowerCase();将字符全部转成小写
??????System.out.println(new?String(“HELLO”).toLowerCase());
??????结果为：hello
17)?public?boolean?startsWith(String?str);判断字符串是否由指定的字符串开头
??????String?s=”fwofsdfjwkfs”;
??????System.out.println(s.startsWith(“fw”));
??????System.out.println(s.startsWith(“wf”));
??????结果为：true
??????????????false
18)?public?boolean?endsWith(String?str):判断字符串是否由指定的字符串结尾
??????String?s=”fwefsdgjgrg”;
??????System.out.println(s.endsWith(“fe”));
??????System.out.println(s.endsWith(“rg”));
??????结果为：false
??????????????True
19?public?boolean?equals(String?str):判断两个字符串是否相等,区分大小写
?????String?s1=”hello”;
?????String?s2=new?String(“hello”);
?????String?s3=”Hello”;
?????System.out.println(“s1==s2---à”+(s1.equals(s2)));
?????System.out.println(“s1==s3---à”+(s1.equals(s3)));
?????结果为：true
?????????????False
20）public?boolean?equalsIgnoreCase(String?str):不区分大小写判断俩个字符串是否相等
String?s1=”hello”;
String?s2=”HEllo”;
System.out.println(“s1==s2--à”+(s1.equalsIgnoreCase(s2)));
结果为：true
21)?public?String?replaceAll(String?str1，String?str2);将字符串中str1替换成str2
String?s=”geowfjsklgoasdf”;
System.out.println(s.replaceAll(“f”,”s”));
结果为：geowsjsklgoasds
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