Code block of anonymous object in Java

Posted 2022-08-04 SamDlex

I came across this way of coding:

List<String> lsit = new ArrayList<String>()
add("hello world");
add("China!");
add("The Great Wall!");
;

I have never coded like this. But I think it is good way to initial the list object. In recent days,I call an API,which needs an list object as a parameter. The traditional way is to create a List object first,then call its add method to add my parameter,and pass onto the API.

It is convenient to create an anonymous List object ,and use a code block to add the paramed which needed by the API. So let’s talk about the code block.

Here is A class:

public class A
  public A()
    System.out.println("Hello 8888");
  
  // Here is a code block
  
    System.out.println("Hello world");
  

You know what! The code block is going to be executed after the constructor of A is executed. The output of A object looks like this:

Hello 8888

We can make use of the feature. I assume that we have a function or method like the following:

public float getPriceOfFruit(List<Fruit> list)
  ...

Now we can do like this:

List<Fruit> list = new ArrayList<Fruit>()
add(new Apple());
add(new Pear());
add(new Organe())
;
float total = getPriceOfFruit(list);

As you see that. It is convenient to use this way to initialize the parameter.