写一个MyArrayList类,重写List中的方法

发布网友发布时间：2024-01-02 14:56

共1个回答

热心网友时间：2024-06-13 05:03

import java.util.Arrays;

public class ListOfMy{
    private Object[] obj;
    private int num=0;

    public ListOfMy(){
        obj=new Object[0];
    }

    public int size(){
        return num;
    }
    public boolean isEmpty() {
        if(obj==null || obj.length<1){
            return true;
        }
        return false;
    }

    public boolean contains(Object element) {
        for(int i=0; i<obj.length; i++){
            if(obj[i].equals(element)){
                return true;
            }
        }
        return false;
    }

    public boolean add(Object element) {
        if(element!=null){
            num++;
            obj=Arrays.copyOf(obj, num);
            obj[num-1]=element;
            return true;
        }
        return false;
    }
    public boolean remove(Object element){
        boolean f=false;
        for(int i=0,j=0; i<obj.length; i++){
            if(!obj[i].equals(element)){
                obj[j++]=obj[i];
                f=true;
            }
        }
        if(f){
            obj=Arrays.copyOf(obj, --num);
        }
        return f;
    }

    public void clear() {
        obj=new Object[0];
        num=0;
    }

    public Object get(int index)throws Exception{
        if(index<0 || index>num){
            throw new Exception("index无效");
        }
        return obj[index];
    }

    public int set(int index, Object element)throws Exception{
        if(index<0 || index>num){
            throw new Exception("index无效");
        }
        obj[index]=element;
        return index;
    }

    public void insert(int index, Object element)throws Exception{
        if(index<0 || index>num){
            throw new Exception("index无效");
        }
        num++;
        obj=Arrays.copyOf(obj, num);
        for(int i=0; i<index; i++){
            obj[i]=obj[i];
        }
        for(int i=num-1; i>index; i--){
            obj[i]=obj[i-1];
        }
        obj[index]=element;
    }

    public Object remove(int index)throws Exception{
        if(index<0 || index>num){
            throw new Exception("index无效");
        }
        Object ob=null;
        for(int i=0, j=0;i<num;i++){
            if(i!=index){
                obj[j]=obj[i];
                j++;
            }else{
                ob=obj[i];
            }
        }
        if(null!=ob){
            obj=Arrays.copyOf(obj, --num);
        }
        return ob;
    }

    public int indexOf(Object element) {
        for(int i=0; i<obj.length; i++){
            if(obj[i].equals(element)){
                return i;
            }
        }
        return -1;
    }
    public String toString(){
        StringBuilder sb=new StringBuilder("[");
        for(int i=0; i<num; i++){
            if(i>0)sb.append(",");
            sb.append(obj[i]);
        }
        sb.append("]");
        return sb.toString();
    }
}

基本的，请参数，有不对的地方，请自己调试、修改