java:常用类库api

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 1 package com.vince;
 2 
 3 import java.util.Arrays;
 4 
 5 public class StringDemo2 {
 6 
 7     public static void main(String[] args) {
 8         
 9         String str = " fkwefwfa d6737383 ";
10         char c = str.charAt(1);
11         System.out.println(c);
12         
13         System.out.println(str.toCharArray());
14         char[] cs = {'a','b','c'};
15         String s1 = new String(cs);
16         
17         String s2 = new String(cs,0,1);
18         System.out.println(s2);
19         
20         System.out.println(Arrays.toString(str.getBytes()));
21         
22         System.out.println(str.replace('w', '*'));
23         System.out.println(str.replaceAll("\\d", "*"));
24         
25         System.out.println(str.substring(0, 4));
26         
27         System.out.println(Arrays.toString(str.split("d")));
28         
29         System.out.println(str.contains("a"));
30         
31         System.out.println(str.indexOf("f"));
32         System.out.println(str.lastIndexOf("f"));
33         System.out.println(str.isEmpty());
34         
35         System.out.println(str.length());
36         
37         System.out.println(str.trim());
38         
39         System.out.println(str.concat("*****"));
40         System.out.println(String.valueOf(10));
41     }
42 
43 }

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