List集合判断元素是否相同,依据是元素的equals方法。
那我想问的是就下面的例子,复写了equals方法后是在哪里用到复写后的equals方法的??
class Person
{
private String name;
private int age;
Person(String name,int age)
{
this.name=name;
this.age=age;
}
public String getName()
{
return name;
}
public int getAge()
{
return age;
}
public boolean equals(Object obj)
{
if(!(obj instanceof Person))
return false;
Person p = (Person)obj;
return this.name.equals(p.name) && this.age==age;
}
}
class ArryListTest2
{
public static void sop(Object obj)
{
System.out.println(obj);
}
public static void main(String[] args)
{
ArrayList al=new ArrayList();
al.add(new Person("lisi01",30));
al.add(new Person("lisi02",32));
al.add(new Person("lisi02",32));
al.add(new Person("lisi03",33));
al.add(new Person("lisi04",35));
al.add(new Person("lisi04",35));
al = singleElement(al);
Iterator it =al.iterator();
while(it.hasNext())
{
Person p = (Person)it.next();//要强转!!!!
sop(p.getName()+"::"+p.getAge());
}
}
public static ArrayList singleElement(ArrayList al)
{
//定义一个临时容器。
ArrayList newAl= new ArrayList();
Iterator it =al.iterator();//
while(it.hasNext())
{
Object obj= it.next();
//System.out.println();
if(!newAl.contains(obj))
newAl.add(obj);
}
return newAl;
}
}
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