//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 false String str = "中国chinese"; for(int i =0 ;i < str.length() ; i ++) { System.out.println(str.substring(i, i+1).matches("[\\u4e00-\\u9fa5]+")); }