length的几个常见的地方介绍

package Io流;

import org.junit.Test;

import java.util.ArrayList;

public class LengthTest {
    @Test
    public void test(){
        //字符串
        String str = "absolute";
        System.out.println(str.length());
        //数组
        int[] a = {1,3,4};
        System.out.println(a.length);
        //集合
        ArrayList<String> list = new ArrayList<>();
        list.add("tom");
        list.add("sun");
        System.out.println(list.size());
    }
}