Java字符串常用方法

朴灿烈づ我的快乐病毒、 2023-01-06 01:40 81阅读 0赞

<table> 
 <thead> 
  <tr> 
   <th>序号</th> 
   <th>方法</th> 
   <th>类型</th> 
   <th>说明</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>1</td> 
   <td>public String(char[] value)</td> 
   <td>构造</td> 
   <td>实例化数组</td> 
  </tr> 
  <tr> 
   <td>2</td> 
   <td>public String(char[] value，int offset,int count)</td> 
   <td>构造</td> 
   <td>分配一个新的<code>String</code>它包含字符数组参数的子数组中的字符。</td> 
  </tr> 
  <tr> 
   <td>3</td> 
   <td>public char charAt(int index)</td> 
   <td>普通</td> 
   <td>返回<code>char</code>值位于指定索引处</td> 
  </tr> 
  <tr> 
   <td>4</td> 
   <td>public char[] toCharArray()</td> 
   <td>普通</td> 
   <td>将此字符串转换为新的字符数组。</td> 
  </tr> 
  <tr> 
   <td>5</td> 
   <td>public String(byte[] bytes)</td> 
   <td>构造</td> 
   <td>字节数组变为字符串</td> 
  </tr> 
  <tr> 
   <td>6</td> 
   <td>public String(byte[] bytes，int offset,int length)</td> 
   <td>构造</td> 
   <td>字节数组部分变为字符串</td> 
  </tr> 
  <tr> 
   <td>7</td> 
   <td>public byte[] getBytes()</td> 
   <td>普通</td> 
   <td>字符串转变为字节数组</td> 
  </tr> 
  <tr> 
   <td>8</td> 
   <td>public byte [] getBytes(String charsetName) throws UnsupportedEncodingException</td> 
   <td>普通</td> 
   <td>编码<code>String</code>使用命名字符集将结果存储到一个新的字节数组中</td> 
  </tr> 
  <tr> 
   <td>9</td> 
   <td>public boolean equals(String anObject)</td> 
   <td>普通</td> 
   <td>区分大小写判断</td> 
  </tr> 
  <tr> 
   <td>10</td> 
   <td>public boolean equalsIgnoreCase(String anotherString)</td> 
   <td>普通</td> 
   <td>不区分大小写判断</td> 
  </tr> 
  <tr> 
   <td>11</td> 
   <td>public int compareTo(String anotherString)</td> 
   <td>普通</td> 
   <td>字符串大小比较</td> 
  </tr> 
  <tr> 
   <td>12</td> 
   <td>public int compareToIgnoreCase(String str)</td> 
   <td>普通</td> 
   <td>不区分大小写字符串进行比较</td> 
  </tr> 
  <tr> 
   <td>13</td> 
   <td>public boolean contain(String s)</td> 
   <td>普通</td> 
   <td>判断子字符串是否存在</td> 
  </tr> 
  <tr> 
   <td>14</td> 
   <td>public int indexOf(String str)</td> 
   <td>普通</td> 
   <td>从头查找指定字符串的位置，找不到返回-1</td> 
  </tr> 
  <tr> 
   <td>15</td> 
   <td>public int indexOf(String str,int fromIndex)</td> 
   <td>普通</td> 
   <td>从指定位置查找指定字符串位置</td> 
  </tr> 
  <tr> 
   <td>16</td> 
   <td>public int lastIndexOf(String str)</td> 
   <td>普通</td> 
   <td>由后向前查找指定字符串的位置</td> 
  </tr> 
  <tr> 
   <td>17</td> 
   <td>public int lastIndexOf(String str,int fromIndex)</td> 
   <td>普通</td> 
   <td>从指定位置由后向前查找指定字符串的位置</td> 
  </tr> 
  <tr> 
   <td>18</td> 
   <td>public boolean startsWith(String prefix)</td> 
   <td>普通</td> 
   <td>判断是否以指定字符串开头</td> 
  </tr> 
  <tr> 
   <td>19</td> 
   <td>public boolean startsWith(String prefix,int toffset)</td> 
   <td>普通</td> 
   <td>由指定位置判断是否以指定字符串开头</td> 
  </tr> 
  <tr> 
   <td>20</td> 
   <td>public boolean endsWith(String prefix)</td> 
   <td>普通</td> 
   <td>判断是否以指定字符串终结</td> 
  </tr> 
  <tr> 
   <td>21</td> 
   <td>public String replaceAll(String regex,String replaceFirst)</td> 
   <td>普通</td> 
   <td>全部替换</td> 
  </tr> 
  <tr> 
   <td>22</td> 
   <td>public String replaceFirst(String regex,String replaceFirst)</td> 
   <td>普通</td> 
   <td>替换首个</td> 
  </tr> 
  <tr> 
   <td>23</td> 
   <td>public String[] split(String regex)</td> 
   <td>普通</td> 
   <td>按照指定字符串全部拆分</td> 
  </tr> 
  <tr> 
   <td>24</td> 
   <td>public String[] split (String regex,int limit)</td> 
   <td>普通</td> 
   <td>按照指定字符串拆分指定个数后面不拆了</td> 
  </tr> 
  <tr> 
   <td>25</td> 
   <td>public String substring(int beginIndex)</td> 
   <td>普通</td> 
   <td>从指定索引截取到结尾</td> 
  </tr> 
  <tr> 
   <td>26</td> 
   <td>public String substring(int beginIndex,int endIndex)</td> 
   <td>普通</td> 
   <td>截取指定范围中三子字符串</td> 
  </tr> 
  <tr> 
   <td>27</td> 
   <td>public static String format(String format, … args)</td> 
   <td>普通</td> 
   <td>根据指定结构进行文本格式化</td> 
  </tr> 
  <tr> 
   <td>28</td> 
   <td>toUpperCase</td> 
   <td>普通</td> 
   <td>小写转换为大写</td> 
  </tr> 
  <tr> 
   <td>29</td> 
   <td>concat</td> 
   <td>普通</td> 
   <td>连接字符串</td> 
  </tr> 
 </tbody> 
</table>

byte[] 数组内容必须为字符型 否则转换String会乱码
    System.out.println( Arrays.toString(strF.split("\\.") ));

[Java 需要转义的字符][Java]

package com.msc.example;
    
    import java.util.Arrays;
    
    public class JavaString { 
        private char car[] = new char[]{ 'a','p','p','5','y','你','x'} ;
        private byte bye[] = new byte[]{ 2,'b',2,1,5} ;
        private String strA="java string test" ;
        private String strB="java string text" ;
        private String strC="ccc string text" ;
        private String strD="cCc string text" ;
        private String strF="java.string.text" ;
        public static void main(String[] args) { 
          JavaString test = new JavaString() ;
            test.testThird();
        }
        public void testThird(){ 
            System.out.println(strA.startsWith("java"));
            System.out.println(strA.endsWith("st"));
            System.out.println( strA.replaceAll("t","T") );
            System.out.println( strA.replaceFirst("a","A") );
            System.out.println( Arrays.toString(strF.split("\\.") ));
            System.out.println( strB.substring(5));
            System.out.println( strB.substring(5,10));
            System.out.println( strB.toUpperCase());
            System.out.println(strA.concat(strB));
        }
        public void testSecond(){ 
            System.out.println(strA.equals(strA));
            System.out.println(strC.equals(strD));
            System.out.println(strC.equalsIgnoreCase(strD));
            System.out.println(strC.compareTo(strD));
            System.out.println(strC.compareToIgnoreCase(strD));
            System.out.println(strA.contains("test"));
            System.out.println(strA.indexOf("s"));
            System.out.println(strA.indexOf("s",6));
            System.out.println(strA.lastIndexOf("s"));
            System.out.println(strA.lastIndexOf("s",6));
        }
        public void testFirst(){ 
            System.out.println("-------------构造方法------------");
            String strD= new String("实例化数组") ;
            System.out.println(strD);
            String strE= new String(car,2,4) ;
            System.out.println(strE);
            //byte必须为字符型 否则乱码
            String strF = new String(bye) ;
            System.out.println(strF);
            String strG = new String(bye,1,2) ;
            System.out.println(strG);
            System.out.println("-------------普通方法------------");
            char carB[] = strA.toCharArray() ;
            System.out.println(carB);
            byte byeB[] = strA.getBytes() ;
            System.out.println(Arrays.toString(bye));
            System.out.println(Arrays.toString(byeB));
            String strW = new String(byeB) ;
            System.out.println(strW);
            strW = new String(bye) ;
            System.out.println(strW);
            char c = strA.charAt(5) ;
            System.out.println(c);
        }
    
    }

[Java]: https://blog.csdn.net/qq_21480607/article/details/112613601