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顺序表各种功能的实现

public class Demo09 {       public static void main(String[] args) {           MyArrayList myArrayList = new MyArrayList();        myArrayList.add(0,1);        myArrayList.add(1,2);        myArrayList.add(1,3);        myArrayList.add(2,4);        myArrayList.show();//打印顺序表        myArrayList.add(3,99);        myArrayList.show();        System.out.println(myArrayList.key(99));//判断是否有key元素，true为有        System.out.println(myArrayList.keyNum(99));//输出key元素的位置        System.out.println(myArrayList.getPos(3));//输出pos下标的元素        myArrayList.replace(3,88);//替换pos位置的元素为val        myArrayList.show();        myArrayList.del(88);//删除第一次出现的关键字key        myArrayList.show();        System.out.println(myArrayList.getLegth());//获取长度        myArrayList.clear();//清空顺序表        myArrayList.show();    }}class MyArrayList{       //普通成员变量    public int[] elem;    public int usedSize;    //构造方法    public MyArrayList(){           this.elem = new int[1];    }    //判断是否有key元素    public boolean key (int key){           for (int i = 0 ; i < this.usedSize; i++ ){               if(elem[i] == key){                   return true;            }        }        return false;    }    //输出key元素的下标    public int keyNum (int key){           for (int i = 0 ; i < this.usedSize; i++ ){               if(elem[i] == key){                   return i;            }        }        return -1;    }    //获取pos下标位置的元素    public int getPos(int pos){           if (pos<0||pos>=this.usedSize) {               return -1;        }        return this.elem[pos];    }    //替换pos位置的元素为val    public void replace(int pos,int val){           if (pos<0||pos>=this.usedSize) {               System.out.printf("pos不在范围内");        }else {               this.elem[pos] = val;        }    }    //删除第一次出现的关键字key    public void del (int key){           for (int i = 0; i < this.usedSize; i++) {               if(elem[i] == key){                   for (;i
   
    this.usedSize || pos<0){               return;        }        for (int i = this.usedSize-1;i >= pos ;i--){               elem[i+1] = elem[i];        }        this.elem[pos] = data;        this.usedSize++;    }    //扩容    public void expand(){           int[] tmp = new int[this.elem.length*2];        for (int i = 0 ;i < this.elem.length ; i++ ){               tmp[i] = this.elem[i];        }        this.elem = tmp ;        return ;    }    //打印顺序表    public void show(){           for (int i = 0; i < this.usedSize; i++) {               System.out.print(this.elem[i] + " ");        }        System.out.println();    }}