Java中使用instanceof判断对象类型的示例

{
  "getTime": "2023-08-13 17:50:12",
  "getValue": [
    "13",
    350,
    193.62,
    37,
    "1813"
  ]
}

public static Double getDouble(Object obj) {
  if (obj == null) return null;
  Double result = null;
  try {
      if (obj instanceof Integer) {
          result = ((Integer) obj).doubleValue();
      } else if (obj instanceof Long) {
          result = ((Long) obj).doubleValue();
      } else if (obj instanceof Double) {
          result = (Double) obj;
      } else if (obj instanceof BigDecimal) {
          result = ((BigDecimal) obj).doubleValue();
      } else if (obj instanceof String) {
          result = Double.parseDouble((String) obj);
      }
  } catch (Exception e) {
      log.info("类型转换异常");
      e.printStackTrace();
  }
  return result;
}

public static void f1() {
   String result = "{\n" +
           "  \"getTime\": \"2023-08-13 17:50:12\",\n" +
           "  \"getValue\": [\n" +
           "    \"13\",\n" +
           "    350,\n" +
           "    193.62,\n" +
           "    37,\n" +
           "    \"1813\"\n" +
           "  ]\n" +
           "}";
   JSONObject jsonResult = (JSONObject) JSON.parse(result);
   List<Object> listResult = (List<Object>) jsonResult.get("getValue");
   List<Double> listResultD = new ArrayList<>();
   //类型转换
   listResult.forEach(item -> {
       listResultD.add(getDouble(item));
   });
   //遍历结果
   listResultD.forEach(item -> {
       System.out.println("" + item);
   });
}

public static Double getDouble(Object obj) {
  if (obj == null) return null;
  Double result = null;
  try {
      if (obj instanceof Integer) {
          result = ((Integer) obj).doubleValue();
      } else if (obj instanceof Long) {
          result = ((Long) obj).doubleValue();
      } else if (obj instanceof Double) {
          result = (Double) obj;
      } else if (obj instanceof BigDecimal) {
          result = ((BigDecimal) obj).doubleValue();
      } else if (obj instanceof String) {
          result = Double.parseDouble((String) obj);
      }
  } catch (Exception e) {
      log.info("类型转换异常");
      e.printStackTrace();
  }
  return result;
}

public static void f2() {
  List<Object> list01 = new ArrayList<>();
  Integer integerV = 813;
  Long longV = 209206L;
  Double doubleV = 209207.13D;
  BigDecimal bigDecimal01 = new BigDecimal("209208.23");
  BigDecimal bigDecimal02 = new BigDecimal("209209");
  String strV = "209210.35";
  list01.add(integerV);
  list01.add(longV);
  list01.add(doubleV);
  list01.add(bigDecimal01);
  list01.add(bigDecimal02);
  list01.add(strV);
  List<Double> list02 = new ArrayList<>();
  //类型转换
  list01.forEach(item -> {
      list02.add(getDouble(item));
  });
  //遍历结果
  list02.forEach(item -> {
      System.out.println("" + item);
  });
}