public static boolean checkDifferent(String str) {
if (str.isEmpty())return true;
int[] flag=new int[128];
//扫描字符串 for (int i = 0; i < str.length(); i++) {
int c=(str.charAt(i));
if (flag[c]>0) {
System.out.println("str = " + str.charAt(i)); return false; }
else { flag[c]++; } } return true;
}
输出字符串的数量
public static String findChar(){
String str="beautiful";
char[] chars = str.toCharArray();
Map<Character, Integer> map = new TreeMap<Character, Integer>();
for (char c : chars){ if(!(c>='a'&&c<='z'||c>='A'&&c<='Z')){ continue; }
Integer count=map.get(c); //看数目。
if (count == null){ map.put(c,1); }else { map.put(c,count+1); } }
StringBuilder stringBuilder = new StringBuilder();
for (Map.Entry<Character, Integer> m:map.entrySet()){
stringBuilder.append(m.getKey()+"("+m.getValue()+")"); }
return stringBuilder.toString();}
