java数组、字符串拼接

1. 数组实现拼接
 int[] arr ={11,22,33,44,55,66};
 System.out.print("[");
 for (int i = 0; i <arr.length ; i++) {
     if (i==arr.length-1){
         System.out.print(arr[i]);
     }else {
         System.out.print(arr[i]+", ");
     }
 }
 System.out.println("]");


2. String实现字符串拼接
 String[] arr={"11","22","33","44","55"};
 String s="[";
 for (int i = 0; i <arr.length ; i++) {
     if (i==arr.length-1)
     s+=arr[i];
     else {
         s+=arr[i]+", ";
     }
 }
 s+="]";
 System.out.println(s);
3. StringBuilder实现字符串拼接
 String[] ss ={"11","12","13","14","15"};
 StringBuilder s =new StringBuilder();
 s.append("[");
 for (int i = 0; i <ss.length ; i++) {
     if (i==ss.length-1){
         s.append(ss[i]);
     }else {
         s.append(ss[i]).append(", ");
     }
 }
 s.append("]");
 String s1 =s.toString();
 System.out.println(s1);
 4.数组实现反转
 int[] arr={11,22,33,44,55,66};
 for (int start=0,end=arr.length-1;start<=end;start++,end--){
     int tmp = arr[start];
     arr[start]=arr[end];
     arr[end]=tmp;
 }
 System.out.print("[");
 for (int i = 0; i <arr.length ; i++) {
    if (i==arr.length-1){
        System.out.print(arr[i]);
    }
    else {
        System.out.print(arr[i]+", ");
    }
 }
 System.out.println("]");
 5. 字符串实现反转
 Scanner sc =new Scanner(System.in);
 System.out.println("请您输入字符串:");
 String s = sc.nextLine();
 String  s1="";
 for (int i = s.length()-1; i >=0 ; i--) {
     s1+=s.charAt(i);
 }
 System.out.println(s1);
 6.使用StringBuilder实现反转
 Scanner sc =new Scanner(System.in);
 System.out.println("请您输入字符串:");
 String s = sc.nextLine();
 StringBuilder s2 =new StringBuilder(s);
 s2.reverse();
 String s3=s2.toString();
 System.out.println(s3);