Nullpointer Exception unknown resource springmicriservice - spring-boot

Question

cnv any one help me I dont knoe where make mistake,when i run my
application in chrome in browser when type
http://localhost:8100/currency-converter-feign/from/USD/to/INR/quantity/1000
i got this type of erro
This application has no explicit mapping for /error, so you are seeing
this as a fallback.
Fri Jul 17 21:38:29 IST 2020 There was an unexpected error
(type=Internal Server Error, status=500). No message available
java.lang.NullPointerException at
java.math.BigDecimal.multiply(Unknown Source) at
com.main.conteoller.CurrencyconversionController.convertCurencyFfeign(CurrencyconversionController.java:47)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at
sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at
sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at
java.lang.reflect.Method.invoke(Unknown Source) at
org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:215)
at
org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:142)
at
org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102)
at
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895)
at
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:800)
at
org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
at
currencyconvertercontroller.java
package com.main.conteoller;
import java.math.BigDecimal;
import java.util.HashMap;
import java.util.Map;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
import com.main.Bean.ConversionBean;
import com.main.serviceproxy.CurrencyexchangeserviceProxy;
#RestController
public class CurrencyconversionController {
#Autowired
private CurrencyexchangeserviceProxy proxy;
#GetMapping("/currency-converter/from/{from}/to/{to}/quantity/{quantity}")
public ConversionBean convertCurency(#PathVariable String from,
#PathVariable String to,
#PathVariable BigDecimal quantity) {
Map<String, String>uriVariables= new HashMap<>();
uriVariables.put("from", from);
uriVariables.put("to", to);
ResponseEntity<ConversionBean>resp = new RestTemplate()
.getForEntity("http://localhost:8000/currency-exchange/from/{from}/to/{to}",
ConversionBean.class,
uriVariables);
ConversionBean cbresp=resp.getBody();
return new ConversionBean(cbresp.getId(),from,to,cbresp.getConvermultiple(),
quantity,quantity.multiply(cbresp.getConvermultiple()),cbresp.getPort());
}
#GetMapping("/currency-converter-feign/from/{from}/to/{to}/quantity/{quantity}")
public ConversionBean convertCurencyFfeign(#PathVariable String from,
#PathVariable String to,
#PathVariable BigDecimal quantity) {
ConversionBean cbresp=proxy.retrivefromexchange(from, to);
return new ConversionBean(cbresp.getId(),from,to,cbresp.getConvermultiple(),
quantity,quantity.multiply(cbresp.getConvermultiple()),cbresp.getPort());
}
}
currencybean.java
package com.main.Bean;
import java.math.BigDecimal;
public class ConversionBean {
private int id;
private String from;
private String to;
private BigDecimal convermultiple;
private BigDecimal quantity;
private BigDecimal totalCalamount;
private int port;
public ConversionBean() {}
public ConversionBean(int id, String from, String to, BigDecimal convermultiple, BigDecimal quantity,
BigDecimal totalCalamount, int port) {
super();
this.id = id;
this.from = from;
this.to = to;
this.convermultiple = convermultiple;
this.quantity = quantity;
this.totalCalamount = totalCalamount;
this.port = port;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getFrom() {
return from;
}
public void setFrom(String from) {
this.from = from;
}
public String getTo() {
return to;
}
public void setTo(String to) {
this.to = to;
}
public BigDecimal getConvermultiple() {
return convermultiple;
}
public void setConvermultiple(BigDecimal convermultiple) {
this.convermultiple = convermultiple;
}
public BigDecimal getQuantity() {
return quantity;
}
public void setQuantity(BigDecimal quantity) {
this.quantity = quantity;
}
public BigDecimal getTotalCalamount() {
return totalCalamount;
}
public void setTotalCalamount(BigDecimal totalCalamount) {
this.totalCalamount = totalCalamount;
}
public int getPort() {
return port;
}
public void setPort(int port) {
this.port = port;
}
}
currencyexchangeproxy.java
package com.main.serviceproxy;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import com.main.Bean.ConversionBean;
#FeignClient(name="currency-exchange",url="localhost:8000")
public interface CurrencyexchangeserviceProxy {
#GetMapping("/currency-exchange/from/{from}/to/{to}")
public ConversionBean retrivefromexchange(#PathVariable ("from") String from,
#PathVariable ("to") String to);
}

Answer 1

It is occurs due to mismatch of comumn name in your db table and in
your entity class. Because I use micriservices,I call some exchange
rates from another project by provideing its url in my repository, in
that project i privide same name in my entity class and in my db table
,but i declared diffrent name in my exchange service project. there i
declare conversationmultople and here declare convermultiple
.make sure both name same in db and your bean class

Answer 2

#EnableFeignClient service in your springboot main method
for example
package com.main;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.openfeign.EnableFeignClients;
#SpringBootApplication
#EnableFeignClients("com.main.serviceproxy")
public class CurrencyConversionServiceApplication {
public static void main(String[] args) {
SpringApplication.run(CurrencyConversionServiceApplication.class, args);
}
}