List去反复/判断List是否包含某元素/字符串是否包含
Java的几个最最最简单的日常应用：
public class TheProblemsWereNotAProblem {
/**
* 这种方法只适合用来比较一些字符串是否包含的问题
* 比较传入String string中是否含有与传入的String str相同的部分，
* @param list
* @param str
* @return
*/
public static boolean isItIn(String string,String str) throws Exception {
// 自左向右，不论字符串长度是否相同只要前面的字符完全匹配就返回TRUE;
if (string.contains(str)) {// .contains JDK1.5之后才有
return true;
}
return false;
}
/**
* 这种方法适合用来比较List中是否包含某个元素的问题
* 比较传入List list中是否含有与传入的String str相同的元素
* @param list
* @param str
* @return
* @throws Exception
*/
public static boolean isItEquals(List list,String str) throws Exception {
for (int i = 0; i < list.size(); i++) {
if (str.equals(list.get(i).toString())) {
return true;
}
}
return false;
}
/**
* 去除list中重复的元素
* @param l
* @return
* @throws Exception
*/
public static List removeRepeatElement(List l) throws Exception {
Set set = new HashSet();
List list = new ArrayList();
System.out.println();
System.out.println(l.size()+"传入的List的长度");
for (int i = 0; i < l.size(); i++) {
set.add(l.get(i));
}
System.out.println();
System.out.println(set.size()+"处理后set的长度");
System.out.println();
for (Iterator it = set.iterator(); it.hasNext();) {
list.add(it.next());
}
System.out.println(list.size()+"返回的list的长度");
System.out.println();
return list;
}
public static void main(String[] args) throws Exception {
String[] s = new String[] {
"BJ", "SH", "CQ", "TJ", "BJ", "SH", "CQ", "TJ"
};
List l = new ArrayList();
for (int i = 0; i < s.length; i++) {
l.add(s[i]);
}
List list=removeRepeatElement(l);//去重复
for (int i = 0; i < list.size(); i++) {
System.out.println(list.get(i).toString());
}
System.out.println();
//System.out.println(list.toString());
System.out.println(isItIn(list.toString(),"B"));// 返回ture
System.out.println(isItIn(list.toString(),"BJ"));// 返回ture
System.out.println(isItIn(list.toString(),"BJS"));// 返回false
System.out.println();
System.out.println(isItEquals(list,"B"));// 返回flase
System.out.println(isItEquals(list,"BJ"));// 返回ture
System.out.println(isItEquals(list,"BJS"));// 返回false
}
}