/**
* @author lizhibiao
* @date 2018/11/27 17:21
*/
public class User
{
private String userName;
private int age;
private int cutScore;
public String getUserName()
{
return userName;
}
public void setUserName(String userName)
{
this.userName = userName;
}
public int getAge()
{
return age;
}
public void setAge(int age)
{
this.age = age;
}
public int getCutScore() {
return cutScore;
}
public void setCutScore(int cutScore) {
this.cutScore = cutScore;
}
}
public class Test
{
public static void main(String[] args)
{
User user = (User)null;
System.out.println(user);
}
}
public class Test
{
public static void main(String[] args)
{
User user = (User)null;
System.out.println(user.getUserName());
}
}
/**运行结果:
* Hello world!
*
*/
public class App
{
private void commonMethod()
{
System.out.println("commonMethod");
}
private static void staticMethod()
{
System.out.println("我是静态方法");
}
public static void main(String[] args)
{
App app = (App)null;
//调用静态方法,不报错
app.staticMethod();
//调用普通方法,报空指针
app.commonMethod();
}
}
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