手写List第二版

Posted 2020-12-23 yonim

这期比上一期更加简洁，但是功能更加完善，该加的异常处理也都加上了

class ListArrays implements Lists{

    private Object[] data;
    
    // 集合大小
    private int size;
    
    // 集合使用大小
    private int index;
    
     // 初始化数组
     public ListArrays() {
         size = 10;
         data = new Object[size];
    }
     
     
     public ListArrays(int ArrarNum) {
         indexCheck(ArrarNum);
         data = new Object[ArrarNum];
    }
    @Override
    public boolean equals(Object obj) {
        return super.equals(obj);
    }
    
    @Override
    public int size() {
        return size;
    }

    @Override
    public boolean isEmpty() {
        if(size() != 0) {
            return true;
        }
        return false;
    }

    @Override
    public void add(Object e) {
        IsExpansion(index);
        data[index] = e;
        ++index;
    }

    @Override
    public void add(int index, Object element) {
        indexCheck(index);
        data[index] = element;
    }

    @Override
    public boolean remove(Object o) {
        return false;
    }

    @Override
    public void remove(int index) {
        indexCheck(index);
            int numMoved = size - index - 1;
            if (numMoved > 0)
                //   System.arraycopy(需要copy到某个数组, 从copy到的数组下标起步位置, 被copy 的数组, 开始,  结束);
                System.arraycopy(data, index+1, data, index,
                                 numMoved);
            data[--index] = null; 
        
    }

    @Override
    public void clear() {
        index = 0;
        size = 10;
        data = new Object[size];
    }

    @Override
    public Object get(int index) {
        indexCheck(index);
        return data[index];
    }

    @Override  // 数据插入
    public void set(int index, Object obj) {
        indexCheck(index);
        int numMoved = size - index - 1;
        if (numMoved > 0)
            data[index] = obj;
            //   System.arraycopy(需要copy到某个数组, 从copy到的数组下标起步位置, 被copy 的数组, 开始,  结束);
            System.arraycopy(data, index, data, index+1,
                             numMoved);
        ++index; 
    }

    @Override
    public int indexOf(Object o) {
        int j = 0;
        for (int i = 0; i < data.length; i++) {
            if (data[i] == o) {
                j=i;
            }
        }
        return j;
    }

    @Override // 数组截取
    public Object[] subList(int fromIndex, int toIndex) {
    
        return Arrays.copyOfRange(data, fromIndex,toIndex);
    }
    
    // 索引检查
    private void indexCheck(int index) {
        if(index > size || index < 0) {
            try {
                throw new Exception();
            } catch (Exception e) {
                e.printStackTrace();
                System.out.println("索引不能大于数组长度切不能小于0");
            }
        }
    }
    
    @SuppressWarnings("unused")
    private int getIndex() {
        
        return index;
        
    }
    
    // 是否进行扩容
    private void IsExpansion(int index) {
        if(index == size) {
            Object[] obj = new Object[size*2+1];
            obj = Arrays.copyOf(data,size);
            data = obj;
        }
    }
    
}