package com.company.demo;

import java.util.ArrayList;
import java.util.List;

public class ListChecker {

	/**
	 * @param list
	 * @Description:遍歷非空list的非空元素
	 */
	@SuppressWarnings("unchecked")
	private void checkEmpty(List list) {
		if (list != null && !list.isEmpty()) {// list不為null，且list不是empty
			for (int i = 0; i < list.size(); i++) {
				if (null != list.get(i) && !"".equals(list.get(i))) {// 元素不為null或""
					System.out.println("list.get(" + i + ")\t'" + list.get(i) + "'");
				} else {
					// 子元素為空。Do something...
				}
			}
		} else {
			// list為空。Do something...
		}
	}

	/**
	 * @param args
	 * @Description: 測試
	 */
	public static void main(String[] args) {
		ListChecker listChecker = new ListChecker();

		List<String> list_1 = null;
		System.out.println("===list_1===");
		listChecker.checkEmpty(list_1);

		List<String> list_2 = new ArrayList<String>();
		System.out.println("===list_2===");
		listChecker.checkEmpty(list_2);

		List<String> list_3 = new ArrayList<String>();
		list_3.add(null);
		list_3.add("");
		list_3.add(" ");
		list_3.add("null");
		list_3.add("something");
		System.out.println("===list_3===");
		listChecker.checkEmpty(list_3);
	}
}
 

執行結果：