字符串方法equals，equalsIgnoreCase，compareTo和regionMatches。

public class Main 

{/* from 时 代 J     a    v  a - nowjava.com*/

   public static void main(String[] args)

   {

      String s1 = new String("hello"); // s1 is a copy of "hello"

      String s2 = "this is a test";

      String s3 = "Happy Birthday";

      String s4 = "happy birthday";


      System.out.printf(

         "s1 = %s\ns2 = %s\ns3 = %s\ns4 = %s\n\n", s1, s2, s3, s4);


      // test for equality

      if (s1.equals("hello"))  // true
      /*来自 
       时 代 J a v a 公 众 号 - nowjava.com*/

         System.out.println("s1 equals \"hello\"");

      else

         System.out.println("s1 does not equal \"hello\""); 


      // test for equality with ==

      if (s1 == "hello")  // false; they are not the same object

         System.out.println("s1 is the same object as \"hello\"");

      else

         System.out.println("s1 is not the same object as \"hello\"");


      // test for equality (ignore case)

      if (s3.equalsIgnoreCase(s4))  // true

         System.out.printf("%s equals %s with case ignored\n", s3, s4);

      else

         System.out.println("s3 does not equal s4");


      // test compareTo

      System.out.printf(

         "\ns1.compareTo(s2) is %d", s1.compareTo(s2));

      System.out.printf(

         "\ns2.compareTo(s1) is %d", s2.compareTo(s1));

      System.out.printf(

         "\ns1.compareTo(s1) is %d", s1.compareTo(s1));

      System.out.printf(

         "\ns3.compareTo(s4) is %d", s3.compareTo(s4));

      System.out.printf(

         "\ns4.compareTo(s3) is %d\n\n", s4.compareTo(s3));


      // test regionMatches (case sensitive)

      if (s3.regionMatches(0, s4, 0, 5))

         System.out.println("First 5 characters of s3 and s4 match");

      else

         System.out.println(