实现方法的比较,该怎么处理_Java相关

实现方法的比较

Java code

public class People {    private int age;    public int getAge() {        return age;    }    public void setAge(int age) {        this.age = age;    }}

实现一：

Java code

public class Test {    public static void main(String args[]) {        List<People> list = new ArrayList<People>();        List<People> list2 = new ArrayList<People>();        People people1 = null;        for (int i = 0; i < 5; i++) {            people1 = new People();            people1.setAge(i);            list.add(people1);        }                People people2 = null;        for(int j = 0;j < list.size();j++){            people2 = list.get(j);            people2.setAge(j+10);            list2.add(people2);        }    }}

实现二：

Java code

public class Test {    public static void main(String args[]) {        List<People> list = new ArrayList<People>();        List<People> list2 = new ArrayList<People>();        People people1 = null;        for (int i = 0; i < 5; i++) {            people1 = new People();            people1.setAge(i);            list.add(people1);        }                for(int j = 0;j < list.size();j++){            People people2 = list.get(j);            people2.setAge(j+10);            list2.add(people2);        }    }}

问题：
1、两个实现中list2的结果相同吗？为什么？
2、people2的声明哪种好呢？为什么？
3、建议使用哪种实现？

------解决方案--------------------------------------------------------
上面那种好点吧，不过拉出来声明性能应该影响不大吧
------解决方案--------------------------------------------------------
1、结果是相同的。
2、楼主不用纠结变理在循环外还是内声明有什么大的性能区别。所以让代码更清晰，表达更准确上讲，第二种更合适。个人观点。
------解决方案--------------------------------------------------------
肯定是第一种好了第二个太浪费了
------解决方案--------------------------------------------------------
List<People> list = new ArrayList<People>();
List<People> list2 = new ArrayList<People>();
for (int i = 0; i < 5; i++) {
People people1 = new People();
people1.setAge(i);
list.add(people1);
}

for(int j = 0;j < list.size();j++){
list.get(j).setAge(j+10);
list2.add(list.get(j));
}

------解决方案--------------------------------------------------------
第一种指向同一堆空间，第二种在堆中重新创建了新对象吧