for (Integer x: list)

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Playing Javarella

Java Syntax, Level 7, Lesson 9

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Hi, nothing wrong with my code. I'm just asking to clarify about something.

public static void printList(List<Integer> list) {
        for (Integer x: list) System.out.println(x);
        //write your code here
    }

Is my understanding of the 2nd line as: "for every Integer x in the list, print x in every new line", correct? And if you have more information about the function of colons in general in Java, please also tell me. Any help will be appreciated, thanks.

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Guadalupe Gagnon

Level 37 , Tampa, United States

2 May 2019, 02:09

Just to be sure, you do know that x is a variable and can be changed to any name that you want(within the naming rules for variables). This structure is a called a foreach loop and is something the Java creators added in for developers as a short hand to using a for loop, as for loops are most commonly used to do exactly this: iterate through a list from the first element to the last in order. So you can type that instead of typing:

for(int i = 0; i < list.size(); i++)
    sys.out.p(list.get(i));

You can iterate through any list type structure carrying any data using a foreach loop, for Strings:

for(String x:list) // do something

for a List<Cat> list:

for(Cat x : list) //do something

for whatever class you come up with:

for(WhateverClass x : list) // do something

The colon operator doesn't have a single use, it shows up in different places. You can read more about it here: https://stackoverflow.com/questions/2399590/what-does-the-colon-operator-do

Yudhi Pratama

Level 7 , Jakarta, Indonesia

2 May 2019, 02:17

wow, the legend himself. Thanks :)

Guadalupe Gagnon

Level 37 , Tampa, United States

2 May 2019, 04:33

=D If I see a question, I try to answer it. Legend?? I dont know about that lol.