java基础学习总结五(递归算法、冒泡排序)

 1 @Test
 2     /**
 3      * 递归求和
 4      * 5+4+3+2+1=15
 5      */
 6     public void getSum() {
 7         long sum = sum(5);
 8         System.out.println("sum=" + sum);
 9     }
10 
11     public static long sum(int i) {
12         if (1 == i) {
13             return 1;
14         } else {
15             return i + sum(i - 1);
16         }
17     }

 1 @Test
 2     /**
 3      * 冒泡排序
 4      */
 5     public void puppleSort() {
 6         int[] arr = { 12, 23, 4, 3, 14 };
 7         for (int i = 0; i < arr.length; i++) {
 8             for (int j = i + 1; j < arr.length; j++) {
 9                 if (arr[i] < arr[j]) {
10                     int tmp = arr[i];
11                     arr[i] = arr[j];
12                     arr[j] = tmp;
13                 }
14             }
15         }
16         System.out.println(Arrays.toString(arr));
17     }