How to Solve Error: Type mismatch: cannot convert from Object to Car

Problem Description:

A very simple spring project that uses static factory methods to configure bean instances. The directory structure of the project is as follows:

code show as below:

Car.java

 1 package com.tt.spring.beans.factory;
 2 
 3 public class Car {
 4 
 5     private String brand;
 6     private double price;
 7     
 8     public String getBrand() {
 9         return brand;
10     }
11     public void setBrand(String brand) {
12         this.brand = brand;
13     }
14     public double getPrice() {
15         return price;
16     }
17     public void setPrice(double price) {
18         this.price = price;
19     }
20     
21     public Car(){
22         System.out.println("Car's Constructor...");
23     }
24     
25     
26     
27     public Car(String brand, double price) {
28         super();
29         this.brand = brand;
30         this.price = price;
31     }
32     
33     @Override
34     public String toString() {
35         return "Car [brand=" + brand + ", price=" + price + "]";
36     }
37     
38     
39 }

StaticCarFactory.java

1  package com.tt.spring.beans.factory;
 2  
3  import java.util.HashMap;
 4  import java.util.Map;
 5  
6  /** 
7  * Static factory method: you can directly call a static method of a certain class Return Bean instance
 8   */ 
9  public  class StaticCarFactory {
 10  
11      
12      private  static Map<String,Car> cars = new HashMap<String, Car> ();
 13      
14      static {
 15          cars.put("Audi", new Car ("Audi",300000 ));
 16         cars.put("Ford", new Car("Ford",40000 ));
 17      }
 18      
19      // Static factory method 
20      public  static Car getCar(String name){
 21          return cars.get(name);
 22          
23      }
 24      
25 }

beans-factory.xml

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <beans xmlns="http://www.springframework.org/schema/beans"
 3     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4     xmlns:context="http://www.springframework.org/schema/context"
 5     xmlns:p="http://www.springframework.org/schema/p"
 6     xmlns:util="http://www.springframework.org/schema/util"
 7     xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
 8         http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd
 9          http://www.springframework.org/schema/util http: //www.springframework.org/schema/util/spring-util-4.0.xsd" > 
10  
11      <!-- Configure beans through static methods. Note that instead of configuring static factory method instances, but configuring bean instances --> 
12      < bean id ="car1"  
13            class ="com.tt.spring.beans.factory.StaticCarFactory" 
14            factory-method ="getCar" > 
15            < constructor-arg value ="Audi" ></constructor-arg>
16     </bean>
17     
18     
19 </beans>

Main.java:

 1 package com.tt.spring.beans.factory;
 2 
 3 import org.springframework.context.ApplicationContext;
 4 import org.springframework.context.support.ClassPathXmlApplicationContext;
 5 
 6 public class Main {
 7 
 8     public static void main(String[] args){
 9         
10         ApplicationContext ctx = new ClassPathXmlApplicationContext("beans-factory.xml");
11         
12         Car car1 = (Car) ctx.getBean("car1");
13         System.out.println(car1);
14      }
 15 }

Run the Main.java program, the console error is as follows:

Exception in thread “main” java.lang.Error: Unresolved compilation problem:
Type mismatch: cannot convert from Object to Car

at com.tt.spring.beans.factory.Main.main(Main.java:12)

 

Cause Analysis:

First, you need to install jre 1.5.0 and above.

Second,
set your installed jre in eclipse’s’Window”Preference”Java’ and’Install JREs’.

Third, in eclipse’s’Window”Preference ” Java ‘in,
‘ Compiler ‘was set up’ Compiler compliance level ‘of 5.0 or more
(the key is the third step, the compatibility level)

 

problem solved:

Since the jdk version I installed is 1.8.0, the problem should be the Compiler compliance level.

Go to Window->Preference->Java->Compiler and find Compiler compliance level=1.5

 

Change the Compiler compliance level to 1.8:

 

Run the Main.java code again, it runs normally, and the console displays the following information:


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