1.字符串转字符
for(int i = 0; i < str.length ; i++ )
str.charAt(i);
2+3:不想循环的话 可以用一个List装字符,每次装之前调用if(List.contains(..))
package com.xuz.csdn.worldcup.day22;
import java.util.HashMap;
import java.util.Map;
public class HelloWorldCountTest {
public static void main(String[] args) {
String hello = "helloworld!";
Mapmap = new HashMap ();
char[] ch = hello.toCharArray();
for (char c : ch) {
Integer i = map.get(c);
if (i == null) {
map.put(c, 1);
} else {
map.put(c, i.intValue() + 1);
}
}
System.out.println(map);
}
}
或者
static Map sortMap(Map map) {
List list = new LinkedList(map.entrySet());
Collections.sort(list, new Comparator() {
public int compare(Object o1, Object o2) {
int result = ((Comparable) ((Map.Entry) (o1)).getValue())
.compareTo(((Map.Entry) (o2)).getValue());
return result == 0?
((Comparable) ((Map.Entry) (o1)).getKey())
.compareTo(((Map.Entry) (o2)).getKey())
:result;
}
});
Map result = new LinkedHashMap();
for (Iterator it = list.iterator(); it.hasNext();) {
Map.Entry entry = (Map.Entry)it.next();
result.put(entry.getKey(), entry.getValue());
}
return result;
}
public static void main(String[] args)
{
String str = "hello world!";//要转换的字符串
int len = str.length();//字符串长度
String strArray[] = new String[len];
//开始转换
for(int i = 0; i < len; i++)
strArray[i] = str.charAt(i) + "";
//查看结果
for(String s:strArray)
System.out.println(s);
}
直接用st.toCharArray();返回一个char[]数组,非要String的话可以强转
用字符串分割Sting[] ary=st.split("");
st.toCharArray();