字符串用占位符拼接 String ms = MessageFormat.format("{0,number,#.##}", 3.656);

public class Test {
    public static void main(String[] args) {
      String newContent = "\n\tprivate String {0};\n" +
            "\tprivate boolean modify_{0} = false;\n" +
            "\n" +
            "\tpublic String {1}() '{'\n" +
            "\t\treturn {0};\n" +
            "\t'}'\n" +
            "\n" +
            "\tpublic void setBDCDYID(String {0}) '{'\n" +
            "\t\tif (this.{0} != {0}) '{'\n" +
            "\t\t\tthis.{0} = {0};\n" +
            "\t\t\tmodify_{0} = true;\n" +
            "\t\t'}'\n" +
            "\t'}'";
      String dd = MessageFormat.format(newContent,"bdcdyic","setBdcdyid");
      System.out.println(dd);
　　　　//特殊符号{  } 需要用左右单引号围起来  '{'  '}'，否则和占位符冲突
      System.out.println(MessageFormat.format("{1} '{' '}' hello {0} {1}","world","lili"));
   }

   private String id;
   public void setId(String id){
      this.id = id;
   }
}

第二个参数可选。

String ms = MessageFormat.format("{0,number,#.##}", 3.656);

若格式不匹配则报异常  如第二个参数限制为数值  但内容为 String

参考 https://blog.csdn.net/Mr_Tony/article/details/50175447?utm_source=blogxgwz9