javaSE---常用类（2）

 1 public class Panduan {
 2 
 3     public static void main(String[] args) {
 4         String s="lina520lina520lina";
 5          System.out.println(s.contains("lina"));//true
 6          System.out.println(s.contains("zcw"));//false
 7         // System.out.println(s.contains(‘l‘));//no
 8          System.out.println(s.startsWith("lina"));//true
 9          System.out.println(s.endsWith("lina"));//True
10          System.out.println(s.startsWith("lina", 7));//True
11          System.out.println(s.equalsIgnoreCase("LINA520LINA520LINA"));//True
12          System.out.println(s.equals("lina520lian520Lina"));//false
13          System.out.println(s.isEmpty());//false
14          System.out.println(s.intern());//lina520lina520lina
15          System.out.println(s.matches("\\d"));//false
16          System.out.println("\\d".matches(s));//false
17          System.out.println("lina520lina520lina".matches(s));//true
18          
19          
20          
21          
22          
23          
24          
25     }
26 
27 }

 1 public class Pingjie {
 2 
 3     public static void main(String[] args) {
 4         String s="lina520lina520lina";
 5         s.concat("520zcw");
 6         //"lina520lina520lina"
 7         s=s.concat("520zcw");//必须要赋值
 8         //lina520lina520lina520zcw
 9         System.out.println(s);
10         System.out.println("zcw".concat("lina").concat("zcw").concat("lina"));
11         //zcwlinazcwlina字符串的拼接
12     }
13 
14 }

 1 public class Replace {
 2 
 3     public static void main(String[] args) {
 4         String s="lina520lina520lina";
 5         //System.out.println(s.replace("lina", "zcw"));
 6            //zcw520zcw520zcw
 7         System.out.println(s.replace(‘l‘, ‘z‘));//不会出现“”与‘‘之间的替换
 8            //zina520zina520zina
 9         System.out.println(s.replaceAll("\\d", "772"));
10            //lina772772772lina772772772lina
11         System.out.println(s.replaceFirst("\\d", "772"));
12            //lina77220lina520lina
13         System.out.println(s.replace(s, "nima"));
14            //nima  target:目标
15     }

 1 import java.io.UnsupportedEncodingException;
 2 import java.util.Arrays;
 3 
 4 public class Zhuanhuan {
 5 
 6     public static void main(String[] args) throws UnsupportedEncodingException {
 7         String s="lina520lina520lina";
 8         byte[] a=s.getBytes();
 9        // System.out.println(Arrays.toString(a));
10       //  [108, 105, 110, 97, 53, 50, 48, 108, 105, 110, 97, 53, 50, 48, 108, 105, 110, 97]
11 
12         byte[] b=s.getBytes("UTF-8");
13         byte[] c=s.getBytes("GBK");
14         System.out.println(Arrays.toString(b));
15         System.out.println(Arrays.toString(c));
16         
17         
18         char [] cc=new char [100];
19          cc [0] =‘z‘;
20          cc [1] =‘c‘;
21          cc [2] =‘w‘;
22          cc.toString();
23          System.out.println(cc);//字符型数组化字符串
24          
25         s.getChars(0, 4, cc, 3);//从字符串取第0到第4个字符（左闭右开）
26         System.out.println(Arrays.toString(cc));
27          //[z, c, w, l, i, n, a}
28         
29         char [] ccc = s.toCharArray();//字符串化字符数组
30         
31         System.out.println(Arrays.toString(ccc));
32         //[l, i, n, a, 5, 2, 0, l, i, n, a, 5, 2, 0, l, i, n, a]
33         
34         String code=s.toUpperCase();
35         System.out.println(code);
36         //LINA520LINA520LINA
37         
38         String str=code.toLowerCase();
39         System.out.println(str);
40         //lina520lina520lina
41         
42         
43         
44         
45     }
46 
47 }