java:常用类库api

Posted 2021-12-07 juham

 

 

 

 

 

 

 

 

 

 package com.vince;
 
 import java.util.Arrays;
 
 public class StringDemo2 {
 
     public static void main(String[] args) {
         
         String str = " fkwefwfa d6737383 ";
         char c = str.charAt(1);
         System.out.println(c);
         
         System.out.println(str.toCharArray());
         char[] cs = {\'a\',\'b\',\'c\'};
         String s1 = new String(cs);
         
         String s2 = new String(cs,0,1);
         System.out.println(s2);
         
         System.out.println(Arrays.toString(str.getBytes()));
         
         System.out.println(str.replace(\'w\', \'*\'));
         System.out.println(str.replaceAll("\\\\d", "*"));
         
         System.out.println(str.substring(0, 4));
         
         System.out.println(Arrays.toString(str.split("d")));
         
         System.out.println(str.contains("a"));
         
         System.out.println(str.indexOf("f"));
         System.out.println(str.lastIndexOf("f"));
         System.out.println(str.isEmpty());
         
         System.out.println(str.length());
         
         System.out.println(str.trim());
         
         System.out.println(str.concat("*****"));
         System.out.println(String.valueOf(10));
     }
 
 }