java 实现多个list 合并成一个去掉重复的案例
我就废话不多说了,大家还是直接看代码吧~
publicstaticvoidmain(String[]args){ Listlist1=newArrayList (); list1.add(1); list1.add(2); list1.add(3); list1.add(4); List list2=newArrayList (); list2.add(1); list2.add(4); list2.add(7); list2.add(10); List listAll=newArrayList (); listAll.addAll(list1); listAll.addAll(list2); listAll=newArrayList (newLinkedHashSet<>(listAll)); System.out.println(listAll); }
输出:
[1,2,3,4,7,10]
代码要典:
1、合并使用java.util.List.addAll(Collection)
2、去重,借助LinkedHashSet
补充知识:java8lambda小试牛刀,利用Stream把list转map,并将两个list的数据对象合并起来
我就废话不多说了,大家还是直接看代码吧~
publicstaticvoidmain(String[]args){ //集合1 Listlists=newArrayList<>(); SkillUpgrades=newSkillUpgrade(); s.setLv(1); s.setAppearNum(100); lists.add(s); SkillUpgrades2=newSkillUpgrade(); s2.setLv(2); s2.setAppearNum(200); lists.add(s2); //集合1 List listx=newArrayList<>(); SkillUpgradex=newSkillUpgrade(); x.setLv(1); x.setSelectNum(1100); listx.add(x); SkillUpgradex2=newSkillUpgrade(); x2.setLv(2); x2.setSelectNum(1200); listx.add(x2); //把list转map,{k=lv,vaule=并为自身}.SkillUpgrade->SkillUpgrade或Function.identity() Map map=listx.stream() .collect(Collectors.toMap(SkillUpgrade::getLv,SkillUpgrade->SkillUpgrade)); System.out.println("map:="+map); //合并 lists.forEach(n->{ //如果等级一致 if(map.containsKey(n.getLv())){ SkillUpgradeobj=map.get(n.getLv()); //把数量复制过去 n.setSelectNum(obj.getSelectNum()); } }); System.out.println("lists:="+lists); //重复问题 Map keyRedo=listx.stream() .collect(Collectors.toMap(SkillUpgrade::getLv,Function.identity(),(key1,key2)->key2)); //方式二:指定实例的map Map linkedHashMap=listx.stream().collect(Collectors.toMap(SkillUpgrade::getLv, SkillUpgrade->SkillUpgrade,(key1,key2)->key2,LinkedHashMap::new)); } /** *output:map:={1=SkillUpgrade[skillId=null,skillName=null,lv=1,persNum=null,selectNum=1100,appearNum=null],2=SkillUpgrade[skillId=null,skillName=null,lv=2,persNum=null,selectNum=1200,appearNum=null]} *lists:=[SkillUpgrade[skillId=null,skillName=null,lv=1,persNum=null,selectNum=1100,appearNum=100],SkillUpgrade[skillId=null,skillName=null,lv=2,persNum=null,selectNum=1200,appearNum=200]] */
输出结果:
map:={1=SkillUpgrade[skillId=null,skillName=null,lv=1,persNum=null,selectNum=1100,appearNum=null],2=SkillUpgrade[skillId=null,skillName=null,lv=2,persNum=null,selectNum=1200,appearNum=null]}
lists:=[SkillUpgrade[skillId=null,skillName=null,lv=1,persNum=null,selectNum=1100,appearNum=100],SkillUpgrade[skillId=null,skillName=null,lv=2,persNum=null,selectNum=1200,appearNum=200]]
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