Java字符串全部大写或小写

import java.lang.*;

public class StringDemo {

   public static void main(String[] args) {

      // converts all upper case letters in to lower case letters

      String str1 = "SELF LEARNING CENTER";

      System.out.println("string value = " + str1.toLowerCase());



      str1 = "TUTORIALS POINT";

      System.out.println("string value = " + str1.toLowerCase());



      // converts all lower case letters in to upper case letters

      String str2 = "This is codingdict";



      System.out.println("string value = " + str2.toUpperCase());

      str2 = "www.codingdict.com";

      System.out.println("string value = " + str2.toUpperCase());

   }

}