1、Arrays.asList()方法的使用
该方法是将数组转化为list;
该方法不适用于基本数据类型(byte,short,int,long,float,double,boolean);
该方法将数组与列表链接起来,当更新其中之一时,另一个自动更新;
不支持add和remove方法,它的长度是不能改变的;
参考地址:
http://blog.csdn.net/keketrtr/article/details/47108435
https://www.cnblogs.com/shanheyongmu/p/6364320.html
2、List的contains()方法
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说明:该方法判断集合list中包含元素b
语法:list.contains(obj)
package com.wanrong.adminWeb; import java.util.ArrayList; import java.util.List; public class Test1 { public static void main(String[] args) { List<String> listA = new ArrayList<String>(); listA.add("111"); listA.add("222"); listA.add("333"); listA.add("444"); System.out.println(listA.contains("222")); System.out.println(listA.contains("2221")); System.out.println("------------------------------------------------"); List<Object> listB = new ArrayList<Object>(); A a1 = new A("11", "男", "你哥1"); A a2 = new A("12", "男", "你哥2"); A a3 = new A("13", "男", "你哥3"); A a4 = new A("14", "男", "你哥4"); B b1 = new B("15", "男", "你哥5"); listB.add(a1); listB.add(a2); listB.add(a3); System.out.println(listB.contains(a1)); System.out.println(listB.contains(a2)); System.out.println(listB.contains(a4)); System.out.println(listB.contains(b1)); } private static class A { private String age_1; private String sex_1; private String name_1; A(String age_1, String sex_1, String name_1){ age_1 = age_1; sex_1 = sex_1; name_1 = name_1; } } private static class B { private String age_2; private String sex_2; private String name_2; B(String age_2, String sex_2, String name_2){ this.age_2 = age_2; this.sex_2 = sex_2; this.name_2 = name_2; } } }
输出结果:
true false ------------------------------------------------ true true false false
3、java中可以传多个参数的写法
// 方法定义 public void info(String format, Object... arguments); // 调用 logger.info("userid {} get relate actMerId {} actFundId {}", new String[] { userId, actMerId, actFundId });