Contains trong ArrayList Java

ArrayList contains() sử dụng để kiểm tra phần tử có chứa trong mảng hay không.

public boolean contains(Object element)

Trả về true nếu tìm thấy, false nếu phần tử không chứa trong ArrayList.

Ví dụ

import java.util.ArrayList; public class Main { public static void main(String[] args) { ArrayList<String> al = new ArrayList<String>(); al.add("pen"); al.add("pencil"); al.add("ink"); al.add("notebook"); System.out.println("ArrayList contains the string 'ink pen': " + al.contains("ink pen")); System.out.println("ArrayList contains the string 'pen': " + al.contains("pen")); System.out.println("ArrayList contains the string 'pencil': " + al.contains("pencil")); System.out.println("ArrayList contains the string 'book': " + al.contains("book")); ArrayList<Integer> al2 = new ArrayList<Integer>(); al2.add(1); al2.add(99); al2.add(56); al2.add(13); al2.add(44); al2.add(6); System.out.println("'1' is present in arraylist: " + al2.contains(1)); System.out.println("'55' is present in arraylist: " + al2.contains(55)); System.out.println("'44' is there in arraylist: " + al2.contains(44)); System.out.println("'7' is there in arraylist: " + al2.contains(7)); } }

Output:

ArrayList contains the string ink pen: false
ArrayList contains the string pen: true
ArrayList contains the string pencil: true
ArrayList contains the string book: false
1 is present in arraylist: true
55 is present in arraylist: false
44 is there in arraylist: true
7 is there in arraylist: false

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