Java 中的构造函数可以抛出异常吗?
java 8object oriented programmingprogramming更新于 2024/10/14 14:47:00
构造函数用于在创建对象时对其进行初始化。它在语法上类似于方法。不同之处在于构造函数与其类同名，并且没有返回类型。
无需显式调用构造函数，这些构造函数会在实例化时自动调用。
示例
public class Example {
public Example(){
System.out.println("This is the constructor of the class example");
}
public static void main(String args[]) {
Example obj = new Example();
}
}
输出
This is the constructor of the class example
构造函数抛出异常
是的，就像方法一样，您可以从构造函数中抛出异常。但是，如果您这样做，您需要在调用构造函数的方法中捕获/抛出(处理)异常。如果不这样做，将生成编译时错误。
示例
在下面的例子中，我们有一个名为 Employee 的类，其构造函数抛出 IOException，我们在不处理异常的情况下实例化该类。因此，如果您编译此程序，它将生成编译时错误。
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
class Employee{
private String name;
private int age;
File empFile;
Employee(String name, int age, String empFile) throws IOException{
this.name = name;
this.age = age;
this.empFile = new File(empFile);
new FileWriter(empFile).write("Employee name is "+name+"and age is "+age);
}
public void display(){
System.out.println("Name: "+name);
System.out.println("Age: "+age);
}
}
public class ConstructorExample {
public static void main(String args[]) {
String filePath = "samplefile.txt";
Employee emp = new Employee("Krishna", 25, filePath);
}
}
编译时错误
ConstructorExample.java:23: error: unreported exception IOException; must be caught or declared to be thrown
Employee emp = new Employee("Krishna", 25, filePath);
^
1 error
示例
为了使该程序正常工作，请将实例化行包装在 try-catch 中，或者抛出异常。
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
class Employee{
private String name;
private int age;
File empFile;
Employee(String name, int age, String empFile) throws IOException{
this.name = name;
this.age = age;
this.empFile = new File(empFile);
new FileWriter(empFile).write("Employee name is "+name+"and age is "+age);
}
public void display(){
System.out.println("Name: "+name);
System.out.println("Age: "+age);
}
}
public class ConstructorExample {
public static void main(String args[]) {
String filePath = "samplefile.txt";
Employee emp = null;
try {
emp = new Employee("Krishna", 25, filePath);
}catch(IOException ex) {
System.out.println("Specified file not found");
}
emp.display();
}
}
输出
Name: Krishna Age: 25
