在java中创建自定义对象数组
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Creating array of custom objects in java
提问by kishore
I have a 100 records of data which is coming to my system from a service. I want to create 100 Class Objects for each record for serializing it to my Custom Class. I was doing this memory creation inside a for loop as follows
我有 100 条数据记录，这些数据从服务传入我的系统。我想为每条记录创建 100 个类对象，以便将其序列化为我的自定义类。我在 for 循环中创建内存如下
for(int i=0; i < 100; i++)
{
SomeClass s1 = new SomeClass();
//here i assign data to s1 that i received from service
}
Is there any way to create all the 100 objects outside the array and just assign data inside the for loop.
有什么方法可以在数组外创建所有 100 个对象，并在 for 循环内分配数据。
I already tried Array.newInstance and SomeClass[] s1 = new SomeClass[100]
Both result in array of null pointers. Is there any way i can allocate all the memory outside the for loop.
两者都会导致空指针数组。有什么办法可以在for循环之外分配所有内存。
采纳答案by ioreskovic
When you do this:
当你这样做时：
Object[] myArray = new Object[100]
Java allocates 100 places to put your objects in. It does NOT instantiate your objects for you.
Java 分配了 100 个位置来放置您的对象。它不会为您实例化您的对象。
You can do this:
你可以这样做：
SomeClass[] array = new SomeClass[100];
for (int i = 0; i < 100; i++) {
SomeClass someObject = new SomeClass();
// set properties
array[i] = someObject;
}
回答by Harshil
I found below really helpful when creating array of custom objects in single line:
在单行中创建自定义对象数组时，我发现下面非常有用：
public class Hotel {
private int frequency;
private String name;
public Hotel(int frequency,String name){
this.frequency = frequency;
this.name = name;
}
}
public class PriorityQueueTester {
public static void main(String args[]){
Queue<Hotel> hotelPQ = new PriorityQueue<Hotel>();
Hotel h[] = new Hotel[]{new Hotel(4,"Harshil"),new Hotel(5,"Devarshi"),new Hotel(6,"Mansi")};
System.out.println(h[0].getName() + " "+h[1].getName()+" "+h[2].getName());
}
}
