我这个问题出在哪里啊?
来源:3-2 Constructor类的概述和使用
安小圈
2019-12-15 19:03:30
我的person对象的参数一个是String name,一个是int age,怎么换个参数类型就运行不了了
@Test public void demo2() throws Exception { Class class1=Class.forName("com.imooc.relect.Person"); Constructor c=class1.getConstructor(String.class,Integer.class); Person person=(Person) c.newInstance("Tom",20);//相当于 Person person=new Person("Tom",20) person.eat(); } package com.imooc.relect; public class Person { private String name; private int age; public int getAge() { return age; } public String getName() { return name; } public void setAge(int age) { this.age = age; } public void setName(String name) { this.name = name; } public Person(){ } public Person(String name,int age){ this.age=age; this.name=name; } public void eat(){ System.out.println("eat"); } } java.lang.NoSuchMethodException: com.imooc.relect.Person.<init>(java.lang.String, java.lang.Integer) at java.lang.Class.getConstructor0(Class.java:3082) at java.lang.Class.getConstructor(Class.java:1825) at com.imooc.relect.ConstructTest.demo2(ConstructTest.java:23) 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 org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) at org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.junit.runners.Suite.runChild(Suite.java:128) at org.junit.runners.Suite.runChild(Suite.java:27) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) at org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.junit.runner.JUnitCore.run(JUnitCore.java:137) at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68) at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33) at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:230) at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:58)
2回答
同学你好。报错信息显示:找不到对应的方法。由于一个类可以有多个构造方法,在反射中,是根据参数列表来确定究竟使用哪个
Person类中没有参数是(String,Integer)的构造方法,只有参数为(String,int)的构造方法,所以同学改为int就可以了
如果解答了同学的疑问,望采纳~
祝学习愉快~
安小圈
提问者
2019-12-15
我把Integer换成int又能运行了,请问这是为什么呢?
Constructor c=class1.getConstructor(String.class,int.class);
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