public boolean equals(Object x){
 if (!(x instanceof BigDecimal))
   return false;
 BigDecimal xDec = (BigDecimal) x;

 return scale == xDec.scale && intVal.equals(xDec.intVal);
  }

public int compareTo(BigDecimal val){
 /* Optimization: would run fine without the next three lines */
 int sigDiff = signum() - val.signum();
 if (sigDiff != 0)
   return (sigDiff > 0 ? 1 : -1);

 /* If signs match, scale and compare intVals */
 BigDecimal arg[] = new BigDecimal[2];
 arg[0] = this; arg[1] = val;
 matchScale(arg);
 return arg[0].intVal.compareTo(arg[1].intVal);
  }

private static void matchScale(BigDecimal[] val) {
 if (val[0].scale < val[1].scale)
   val[0] = val[0].setScale(val[1].scale);
 else if (val[1].scale < val[0].scale)
   val[1] = val[1].setScale(val[0].scale);
  }

System.out.println(new BigDecimal("1.2").equals(new BigDecimal("1.20"))); //输出false

System.out.println(new BigDecimal("1.2").compareTo(new BigDecimal("1.20")) == 0); //输出true 

System.out.println(new BigDecimal("1.2").equals(new BigDecimal("1.20"))); //输出false
System.out.println(new BigDecimal("1.2").compareTo(new BigDecimal("1.20")) == 0); //输出true
    
System.out.println(new BigDecimal(1.2).equals(new BigDecimal("1.20"))); //输出是?
System.out.println(new BigDecimal(1.2).compareTo(new BigDecimal("1.20")) == 0); //输出是?
  
System.out.println(new BigDecimal(1.2).equals(new BigDecimal(1.20))); //输出是?
System.out.println(new BigDecimal(1.2).compareTo(new BigDecimal(1.20)) == 0);//输出是?