我有一个listView最初具有一些内容。如果得到相同的内容,我通过删除了重复项linkedhashset
。现在,我要复制linkedhashset
内容,即不复制内容到new ArrayList
。
我试图复制
p.addAll(0,lhm); // P is the instance of ArrayList and lhm is linkedHashset instance
但是,也ArrayList
包括重复内容。
例子 :
ArrayList<Price> p = new ArrayList<Price>();
p.add(new Price("Banana", 60));
p.add(new Price("Apple", 80));
LinkedHashSet<Price> lhm = new LinkedHashSet<Price>(p);
lhm.add(new Price("Banana", 20));
lhm.add(new Price("Apple", 40));
lhm.add(new Price("Orange", 30));
for(Price pr:lhm)
{
System.out.println(pr);
}
Price duplicate = new Price("Banana", 20);
System.out.println("inserting duplicate object...");
lhm.add(duplicate);
lhm.add(new Price("Apple", 40));
p.addAll(0,lhm);
System.out.println("After insertion:");
for(Price pr:lhm)
{
System.out.println(pr);
}
for (int i = 0; i < p.size(); i++) {
System.out.println(p.get(i).getItem() +"-" +p.get(i).getPrice());
}
价格等级
class Price
{
private String item;
private int price;
public Price(String itm, int pr)
{
this.item = itm;
this.price = pr;
}
public int hashCode()
{
System.out.println("In hashcode");
int hashcode = 0;
hashcode = price;
//System.out.println(hashcode);
hashcode+= item.hashCode();
// System.out.println(hashcode);
return hashcode;
}
public boolean equals(Object obj)
{
System.out.println("In equals");
if (obj instanceof Price)
{
Price pp = (Price) obj;
return (pp.item.equals(this.item) && pp.price == this.price);
}
else
{
return false;
}
}
public String getItem()
{
return item;
}
public void setItem(String item)
{
this.item = item;
}
public int getPrice()
{
return price;
}
public void setPrice(int price)
{
this.price = price;
}
public String toString()
{
return "item: "+item+" price: "+price;
}
}
输出 :
In hashcode
In hashcode
In hashcode
In hashcode
In hashcode
item: Banana price: 60
item: Apple price: 80
item: Banana price: 20
item: Apple price: 40
item: Orange price: 30
inserting duplicate object...
In hashcode
In equals
In hashcode
In equals
//iterating linkedhasset content
After insertion:
item: Banana price: 60
item: Apple price: 80
item: Banana price: 20
item: Apple price: 40
item: Orange price: 30
// iterating ArrayList p content
Banana-60
Apple-80
Banana-20
Apple-40
Orange-30
Banana-60
Apple-80 <-- duplicate
下一行只是从第0个索引开始将所有元素插入到arraylist中
p.addAll(0,lhm);
并且,使用这些行添加的元素仍然存在于arraylist中:
p.add(new Price("Banana", 60));
p.add(new Price("Apple", 80));
因此,如果您不希望重复项,则应在添加链结哈希集中的项之前清除数组列表。IE
p.clear();
p.addAll(lhm); // and, at this point you don't need the index.
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