如何初始化一个对象数组？

I just looked at this SO Post:

我刚刚看了这篇SO帖子:

However, the Columbia professor's notes does it the way below. See page 9.

但是,哥伦比亚大学教授的笔记就是这样做的。见第9页。

Foo foos = new Foo[12] ;

Which way is correct? They seem to say different things.

哪种方式正确?他们似乎说不同的事情。

Particularly, in the notes version there isn't [].

特别是,在笔记版本中没有[]。

5 个解决方案

#1

This simply won't compile in Java (because you're assigning a value of an array type to a variable of a the non-array type Foo):

这根本不会用Java编译(因为你要将数组类型的值赋给非数组类型Foo的变量):

Foo foos = new Foo[12];

it's rejected by javac with the following error (See also: http://ideone.com/0jh9YE):

它被javac拒绝并出现以下错误(另请参阅:http://ideone.com/0jh9YE):

test.java:5: error: incompatible types
        Foo foos = new Foo[12];

To have it compile, declare foo to be of type Foo[] and then just loop over it:

要让它编译,将foo声明为Foo []类型,然后循环它:

Foo[] foo = new Foo[12];  # <<<<<<<<<

for (int i = 0; i < 12; i += 1) {
    foos[i] = new Foo();
}

#2

Foo[] foos = new Foo[12] ; //declaring array 

for(int i=0;i<12;i++){
   foos[i] = new Foo();  //initializing the array with foo object

}

#3

You can't do this

你不能这样做

Foo foos = new Foo[12] ;

change to

Foo[] foos = new Foo[12];

there was a typo in the document on page 9. Also there's a typo on page 10

第9页的文档中有一个拼写错误。第10页也有拼写错误

int[] grades = new int[3]

I would not read the whole document if the typos are on each page.

如果每页都有拼写错误,我就不会阅读整篇文档。

#4

Declare by this way.

通过这种方式宣布。

Foo[] foos = new Foo[12];

#5

//declaring array of 12 Foo elements in Java8 style
Foo[] foos = Stream.generate(Foo::new).limit(12).toArray(Foo[]::new);

// instead of
Foo[] foos = new Foo[12];
for(int i=0;i<12;i++){
   foos[i] = new Foo();

}

#1