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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