Java 의 length, length(), size() 차이점

1. legnth -> 배열의 길이 ( int[], String[], double[] ... )

2. length() -> 문자열의 길이 ( String, StringBuilder ... )

3. size() -> 컬렉션프레임워크 타입의 길이 ( ArrayList, Stack, Queue )

---

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.Queue;
import java.util.Stack;

public class Test {
	
	static class A {}
	
	public static void main(String[] args) {
		
		// 1. length
		int[] arr1 = new int[10];
		String[] arr2 = new String[10];
		double[] arr3 = new double[10];
		A[] arr4 = new A[10];
		
		System.out.println(arr1.length);
		System.out.println(arr2.length);
		System.out.println(arr3.length);
		System.out.println(arr4.length);
		
		
		// 2. length()
		String st1 = "abcde";
		StringBuilder st2 = new StringBuilder("abcdefg");
		
		System.out.println(st1.length());
		System.out.println(st2.length());
		
		
		// 3. size()
		ArrayList list = new ArrayList();
		Stack stack = new Stack();
		Queue queue = new LinkedList();
		
		System.out.println(list.size());
		System.out.println(stack.size());
		System.out.println(queue.size());
		
		
		
	}
	
}