public class A {
    public String[] getSameAppearWord(String[] strs) {
        List<String> list = new ArrayList<String>();
        if(strs.length>0) {
            Set<String> haveWord = this.getHaveWord(strs[0]);
            for(String word : haveWord) {
                boolean allHave = true;
                for(String oneStr : strs) {
                    if(oneStr.indexOf(word) == -1) {
                        allHave = false;
                        break;
                    }
                }
                if(allHave) list.add(word);
            }
        }
        return list.toArray(new String[]{});
    }
    //看第一个字符串中不重复的字符有哪些
    private Set<String> getHaveWord(String word) {
        Set<String> set = new HashSet<String>();
        if(word.length()>0) {
            for(int i=0;i<word.length()-1;i++) {
                set.add(word.substring(i,i+1));
            }
        }
        return set;
    }
    public static void main(String[] args) {
        String a = "aaabbcc"; 
        String b = "addffc" ;
        String c = "eeffac" ; 
        String[] strs = {a,b,c};
        A test = new A();
        String[] sameAppearWord = test.getSameAppearWord(strs);
        for(String str : sameAppearWord) System.out.println(str);
    }

}

------解决方案--------------------
Java code


public class TestSameChar {

    /**
     * 判断多个字符串中重复的字符，并打印输出
     * @param args
     */
    public static void main(String[] args) {
        String a = "aaabbccfe"; 
        String b = "addffe";
        String c = "eeffa";
        String totalString[] = {a, b, c};    //先将多个字符串归并到一个字符串数组中，方便取用
//字符串数组用来判断下一个取的字符是否已经在数组中存在，如果是则代表取的是重复的字符,直接跳过
        char[] arr = new char[a.length()];    
        System.out.println("重复的字符为：");
        for(int i=0; i<a.length(); i++) {
            boolean f = true;    //f代表是否找到重复的字符
            char ch = a.charAt(i);
            if(!isContains(arr, ch)) {    //判断是否取到了重复的字符
                arr[i] = ch;    //如果没有，则先将其存储到字符数组中
                for(int j=1; j<totalString.length; j++) {    //循环遍历每一个字符串数组
                    if(totalString[j].indexOf(ch) == -1) {
                        f = false;
                        break;
                    }
                }
                if(f)
                    System.out.print(ch + " ");
            }
        }
    }
    
    private static boolean isContains(char[] arr, char c) {
        for(int i=0; i<arr.length; i++) {
            if(arr[i] == c)
                return true;
        }
        return false;
    }
}

------解决方案--------------------