public class MyArraylist {public int[] elem;public int usedSize = 0;//0//默认容量private static final int DEFAULT_SIZE = 10;public MyArraylist() {this.elem = new int[DEFAULT_SIZE];}/*** 打印顺序表:* 根据usedSize判断即可*/public void display() {for (int i = 0; i < usedSize; i++) {System.out.println(elem[i] + " ");}System.out.println();}// 新增元素,默认在数组最后新增public void add(int data) {if (isFull()) {elem = Arrays.copyOf(elem,2*elem.length);}elem[usedSize] = data;usedSize++;}/*** 判断当前的顺序表是不是满的！** @return true:满   false代表空*/public boolean isFull() {return usedSize == elem.length;}private boolean checkPosInAdd(int pos) {if (pos < 0 || pos > usedSize) {throw new PosException("pos位置：" + pos);}return true;//合法}// 在 pos 位置新增元素public void add(int pos, int data) {checkPosInAdd(pos);if (isFull()) {elem = Arrays.copyOf(elem, 2 * elem.length);}for (int i = usedSize - 1; i >= pos; i--) {elem[i + 1] = elem[i];}elem[pos] = data;usedSize++;}// 判定是否包含某个元素public boolean contains(int toFind) {for (int i = 0; i < usedSize; i++) {if (elem[i] == toFind) {return true;}}return false;}// 查找某个元素对应的位置public int indexOf(int toFind) {for (int i = 0; i < usedSize; i++) {if (elem[i] == toFind) {return i;}}return -1;}// 获取 pos 位置的元素public int get(int pos) {checkPosInAdd(pos);if (isEmpty()) {throw new EmptyException("顺序表为空");}return elem[pos];}private boolean isEmpty() {return usedSize == 0;}// 给 pos 位置的元素设为【更新为】 valuepublic void set(int pos, int value) {checkPosInAdd(pos);if (isEmpty()) {throw new EmptyException("顺序表为空");}elem[pos] = value;}/*** 删除第一次出现的关键字key** @param key*/public void remove(int key) {if (isEmpty()) {throw new RuntimeException("顺序表为空，不能删除");}int index = indexOf(key);for (int i = index; i < usedSize - 1; i++) {elem[i] = elem[i + 1];}usedSize--;}// 获取顺序表长度public int size() {return this.usedSize;}// 清空顺序表public void clear() {usedSize = 0;}
}

public class EmptyException extends RuntimeException{public EmptyException() {}public EmptyException(String msg) {super(msg);}
}

public class PosException extends RuntimeException{public PosException() {}public PosException(String msg) {super(msg);}
}