1.获取List中的前几条数据
list1 = list2.subList(start, end);
start,end分别是第几个到第几个。
2.addAll方法将集合数据依次写入
public static void main(String[] args) {
List<String> as = Arrays.asList("aa","bb","cc","dd","ee");
List<String> tt = new ArrayList<>();
tt.add("rr");
tt.addAll(as);
System.out.println("输出的数据为:" + tt);
}
3.String数组和List的互相转化
1)String[] --> List
方法一:
//准备一个String数组
String[] strs = {"aa","bb","cc"};
//String数组转List
List<String> strsToList1= Arrays.asList(strs);
for(String s:strsToList1){
System.out.println(s);
}
方法二:
//准备一个String数组
String[] strs = {"aa","bb","cc"};
//String数组转List
List<String> strsToList2=new ArrayList<>();
Collections.addAll(strsToList2,strs);
for(String s:strsToList2){
System.out.println(s);
}
2)List --> String[]
//先准备一个List
List<String> testList=new ArrayList<>();
testList.add("a");
testList.add("b");
testList.add("c");
//List转String
String[] strs1=testList.toArray(new String[testList.size()]);
for(String s:strs1){
System.out.println(s);
}
4.Map值转换成List
List<Value> list = new ArrayList<Value>(map.values());