JavaPython:List

Java vs Python

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Pythoni järjendile on Javas lähim sarnane andmetüüp kas array või ArrayList.

Python järjend --> Java array

An array is indexed like a Python list, with square brackets:

students[0] or letters[i][j].

Declaring an array does not create one. The declaration tells how many dimensions the array has, but never its size:

for example, char[][] letters.

To create one, use the word new, then its type and size;

new char[5][5].

Python has list literals:

[1, 2, 3, 4]. 

Java has two different syntaxes for array literals: In a declaration (only):

int[] numbers = {1, 2, 3, 4};

Other places:

new int[] {1, 2, 3, 4} 

Java has no equivalent to Python's list[i:j] notation.

Python järjend --> Java ArrayList

An ArrayList acts more like a Python list, but uses only object syntax. There are no literals.

ArrayList<String> languages = new ArrayList<String>();
languages.add("Python");  // append to list
String oldLanguage = languages.get(0);
languages.set(0, "Java");
Some additional methods: boolean isEmpty(), boolean contains(object), int size(), type remove(index).

Näide

Java

Python

<syntaxhighlight lang="java" line="1" > //arraylist is closest with list in python ArrayList<Integer> aList = new ArrayList<Integer>(); //add aList.add(1); aList.add(3); aList.add(2); aList.add(4); //index int n = aList.get(0); //get sub list List<Integer> subList = aList.subList(0, 2); //1, 3 </syntaxhighlight>

<syntaxhighlight lang="python" line="2" > aList = [] aList = [1, 'mike', 'john'] append aList.append(2) extend aList.extend(["new","list"]) print aList [1, 'mike', 'john', 2, 'new', 'list'] aList = [0,1,2,3,4,5,6] size print len(aList) 7 print aList[2] 2 print aList[0:3] [0, 1, 2] print aList[2:] [2, 3, 4, 5, 6] print aList[-2] 5 lists are mutable aList[0] = 10 print aList [10, 1, 2, 3, 4, 5, 6] </syntaxhighlight>