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package org.hujian.jdk.list;

import org.hujian.common.JvmTestRunner;

import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.List;

/**
 * Created on 2018/11/5 11:31.
 */
public class TestArrayListInitSize extends JvmTestRunner {
    /**
     * 在这里实现测试逻辑，不提供参数列表以及返回值，执行该方法应该测试到
     * 你需要实现的所有逻辑，本方法单线程执行（main）
     */
    @Override
    protected void execute() {
        //Constructs an empty list with an initial capacity of ten.
        List<Integer> intList = new ArrayList<>();

        System.out.println(getCapacity(intList));

        intList.add(1);

        System.out.println(getCapacity(intList));
    }

    private long getCapacity(List arrayList) {
        try {
            Field field = ArrayList.class.getDeclaredField("elementData");
            field.setAccessible(true);
            return ((Object[])field.get(arrayList)).length;
        } catch (NoSuchFieldException e) {
            return -1;
        } catch (IllegalAccessException e) {
            return -2;
        }
    }

    public static void main(String[] args) {
        new TestArrayListInitSize().execute();
    }
}