字符串charAt,indexOf,startsWith,endsWith,matches,StringBuffer的reverse().toString(),Character 的isLowerCase, toUpperCase, map的containsKey( ),size(),keySet();
一、字符串
字符串charAt,indexOf,startsWith,endsWith,matches,split
String[] arr = str.split(",");
二、数组
Integer[] arr = {1,3,5,2,4,6};
//默认升序
Arrays.sort(arr);
//实现降序
Arrays.sort(arr, new Comparator<Integer>(){
public int compare(Integer A, Integer B){
return B-A;
}
})
三、StringBuffer
String reverse = stringbuffer.reverse().toString();
四、Character
Character 的isLowerCase, toUpperCase
五、list
Collections.sort(list);
Collections.sort(list, new Comparator<Interval>(){
public int compare(Interval A, Interval B){
if(A.start!=B.start){
return (A.start-B.start);
}else{
return (A.end-B.end);
}
}
})
Collections.reverse(list);
六、map
Map<Integer,Integer> map = new HashMap<Integer, Integer>();
map.put(1,1);
map.put(2,2);
map.put(3,3);
map.size();
map.contiansKey(1);
for(Integer tmp: map.keySet){
Integer v = map.get(tmp);
}