扩容原则: 若参数值大于底层数组长度的1.5倍,则数组的长度就扩容为这个参数值:若小于底层数组长度的1.5倍,则数组长度就扩容为底层数组长度的1.5倍. ensureCapacity提高效率 final int N = 10000000; Object obj = new Object(); //没用调用ensureCapacity()方法初始化ArrayList对象 ArrayList list = new ArrayList(); long startTime = System.curren
import java.util.ArrayList; import java.util.Iterator; public class StringSampleDemo { public static void main(String[] args) { ArrayList al = new ArrayList(); al.add(new Student("zhangsan1", 20, "男")); al.add(new Student("zhangsa