在Java中，有两种类型的异常-已检查和未检查的异常。 这是摘要：
- 已检查 -扩展
java.lang.Exception，以获取可恢复的条件，尝试尝试捕获异常，并编译错误。 - 未选中 -扩展
java.lang.RuntimeException，以恢复不可恢复的条件，例如编程错误，无需try-catch，运行时错误。
1.自定义检查异常
注意
一些流行的检查异常：IOException，FileNotFoundException
1.1如果客户端能够从异常中恢复，请使其成为已检查的异常。 要创建自定义的检查异常，请扩展java.lang.Exception
NameNotFoundException.java
package com.mkyong.examples.exception;
public class NameNotFoundException extends Exception {
public NameNotFoundException(String message) {
super(message);
}
}1.2对于检查的异常，您需要尝试捕获异常。
CustomerService.java
package com.mkyong.examples;
import com.mkyong.examples.exception.NameNotFoundException;
public class CustomerService {
public Customer findByName(String name) throws NameNotFoundException {
if ("".equals(name)) {
throw new NameNotFoundException("Name is empty!");
}
return new Customer(name);
}
public static void main(String[] args) {
CustomerService obj = new CustomerService();
try {
Customer cus = obj.findByName("");
} catch (NameNotFoundException e) {
e.printStackTrace();
}
}
}输出量
com.mkyong.examples.exception.NameNotFoundException: Name is empty! at com.mkyong.examples.CustomerService.findByName(CustomerService.java:10) at com.mkyong.examples.CustomerService.main(CustomerService.java:39) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)
2.自定义未经检查的异常
注意
一些流行的未经检查的异常：NullPointerException，IndexOutOfBoundsException，IllegalArgumentException
2.1如果客户端无法采取任何措施从异常中恢复，请将其设置为未经检查的异常。 要创建自定义的未经检查的异常，请扩展java.lang.RuntimeException
ListTooLargeException.java
package com.mkyong.examples.exception;
public class ListTooLargeException extends RuntimeException{
public ListTooLargeException(String message) {
super(message);
}
}2.3对于未检查的异常，尝试捕获异常是可选的。
CustomerService.java
package com.mkyong.examples;
import com.mkyong.examples.exception.ListTooLargeException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
public class CustomerService {
public void analyze(List<String> data) {
if (data.size() > 50) {
//runtime exception
throw new ListTooLargeException("List can't exceed 50 items!");
}
//...
}
public static void main(String[] args) {
CustomerService obj = new CustomerService();
//create 100 size
List<String> data = new ArrayList<>(Collections.nCopies(100, "mkyong"));
obj.analyze(data);
}
}输出量
Exception in thread "main" com.mkyong.examples.exception.ListTooLargeException: List can't exceed 50 items! at com.mkyong.examples.CustomerService.analyze(CustomerService.java:25) at com.mkyong.examples.CustomerService.main(CustomerService.java:38) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)
参考文献
翻译自: https://mkyong.com/java/java-custom-exception-examples/
