Code block of anonymous object in Java

I came across this way of coding:

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

  
 

  
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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");
 	}
}

  
 

  
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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
Hello world

  
 

  
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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){
	...
}

  
 

  
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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);

  
 

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

文章来源: blog.csdn.net，作者：WongKyunban，版权归原作者所有，如需转载，请联系作者。

原文链接：blog.csdn.net/weixin_40763897/article/details/114466335