[Java] 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;
  }
}