如何使double为整数时不带小数点

如何使double为整数时不带小数点假设一个double类型的变量被赋值为5，则输出时会显示5.00000怎样才能在输出时去掉小数点？并且当它赋值为小数时（比如5.12）输出时会仍显示小数

public class DoubleTrans{  public static String doubleTrans(double d){  if(Math.round(d)-d==0){   return String.valueOf((long)d);  }  return String.valueOf(d); } public static void main(String args[]){  double a=3.0d,b=3.1d;  System.out.println(doubleTrans(a));  System.out.println(doubleTrans(b)); }}运行结果：3   3.1
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public class s {public static void main(String[] args) {double b=1.1;double c=b-(int)b;if(c==0)System.out.println((int)b);elseSystem.out.println(b); }}