StringBuffer片段
//StringBuffer类可以完成字符串的动态添加、插入和替换等操作。String question = new String("1+1=");int answer = 3;boolean result = (1+1==3);StringBuffer sb = new StringBuffer();sb.append(question);sb.append(answer);sb.append(‘\t‘);sb.append(result);System.out.println(sb);结果为：1+1=3 falseString str = "中国chinese"; for(int i =0 ;i < str.length() ; i ++) { System.out.println(str.substring(i, i+1).matches("[\\u4e00-\\u9fa5]+")); } ?