public class StringDemo {
       public static void main(String[] args) {
               String str1 = "Hello world!This is Java code.";        //聲明并初始化字符串str1
               String str2;                                           //聲明字符串str2
               String str3 = new String("This is Java code.");       //聲明并初始化字符串str3      
               str2 = new String("This is Java code.");             //創建字符串對象str2并初始化
               System.out.println("str1 is: "+str1);
               System.out.println("str2 is: "+str2);
               System.out.println("str3 is: "+str3+"\n");
               System.out.println("Each item of str1 is:");
               for(int i=0;i<str1.length();i++){    
                 char c = str1.charAt(i);                       //使用charAt()方法得到String字符串中指定位置的字符，并利用循環分別輸出 
                 System.out.print("\""+c+"\",");
                 if((i+1)%10==0) System.out.println();
             }
             System.out.println();
             byte b[] = str1.getBytes();
             //使用String類的getBytes()方法，得到str1中所有字符對應的Unicode編碼，并存入byte型數組b中
             System.out.println("Change each item of str1 to unicode is:");
             for(int i=0;i<b.length;i++){    //利用循環分別輸出str1中，所有元素對應的字符的Unicode編碼
                 System.out.print(b[i]+",");
                 if((i+1)%10==0) System.out.println();
             }
             System.out.println();
             System.out.print("The result of comparing str2 and str3 is:");
             System.out.println(str2.equals(str3));
             //將字符串對象str2與str3進行比較，并將返回值輸出
             System.out.println("\nReplace all charcters \"a\" to \"e\" in str2");
             System.out.println("The result of str2.replace() is:"+str2.replace('a','e'));
             //將字符串str2調用replace()方法的結果輸出
             System.out.println("str2 is: "+str2+"\n");
             System.out.print("The result of whether str1 is beginning with \"Hello\":");
             System.out.println(str1.startsWith("Hello"));
             System.out.print("The result of whether str3 is end with \"code.\":");
             System.out.println(str3.endsWith("code.")); 
             System.out.print("The subString of str1 whose position is arange  from  2  to end is:");          
             System.out.println(str1.substring(2));
             System.out.print("The subString of str1 whose position is arange  from  2  to    5  is:");  
             System.out.println(str1.substring(2,5));                    
       }
}