Java实现删除排序数组中重复元素的方法小结【三种方法比较】

ArrayList<Integer> list = new ArrayList<Integer>();
// 去掉数组中重复的元素
public int removeTheagain01(int[] array) {
    if (array == null || array.length == 0) {
      return 0;
    } else if (array.length == 1) {
      return 1;
    } else {
      int i = 0;
      int n = array.length - 1;
      while (i <= n) {
        if (i == n) {
          list.add(array[i]);
          i++;
        } else {
          int j = i + 1;
          if (array[i] == array[j]) {
            while (j <= n && array[i] == array[j]) {
              j++;
            }
          }
          list.add(array[i]);
          i = j;
        }
      }
      for (int k = 0; k < list.size(); k++) {
        array[k] = list.get(k);
      }
      return list.size();
    }
}

public int removeTheagain02(int[] array) {
    if (array == null || array.length == 0) {
      return 0;
    } else if (array.length == 1) {
      return 1;
    } else {
      int end = array.length - 1;
      for (int i = 0; i <= end; i++) {
        if (i < end) {
          int j = i + 1;
          if (array[i] == array[j]) {
            while (j <= end && array[i] == array[j]) {
              j++;
            }
          }
          System.arraycopy(array, j, array, i + 1, end - j + 1);
          end -= j - i - 1;
        }
      }
      return end + 1;
    }
}

public int removeTheagain03(int[] array) {
    if (array == null || array.length == 0) {
      return 0;
    } else if (array.length == 1) {
      return 1;
    } else {
      int temp = array[0];
      int len = 1;
      for (int i = 1; i < array.length; i++) {
        if (temp == array[i]) {
          continue;
        } else {
          temp = array[i];
          array[len] = array[i];
          len++;
        }
      }
      return len;
    }
}