qq飞车骑宠怎么强化:java作业

来源:百度文库 编辑:神马品牌网 时间:2024/05/02 08:48:36
public class Employee {
private int id = 0;
public String name = "No name";
public Employee(){
this.id = 0;
this.name = "No name";
}
public changeData(int id, String name){
this.id = id;
this.name = name;
return;
}
public void print(){
System.out.println("No : " + id);
}
}

class PrintEmp{
public static void main(String args[]){
Employee.description();
System.out.print("Name : " + emp1.name);
Employee emp1 = new Employee(1,"Tanaka");
emp1.print();
System.out.print("Name : " + emp1.name);
Employee emp2 = new Employee();
emp2.print();
System.out.print("Name : " + emp1.name);
emp2.changeData(5,"Yamada");
emp2.print();
System.out.print("Name : " + emp1.name);
}
}
有错误呀
Employee.java:8: 方法声明无效;需要返回类型
public changeData(int id, String name){
^

方法的声明要有返回类型,若不需要返回类型可以改成
public void changeData(int id, String name){
this.id = id;
this.name = name;
}
另外少个构造函数public Employee(int id, String name)
还少这个方法Employee.description();

class Employee
{
private int id = 0;
public String name = "No name";
public Employee()
{
this.id = 0;
this.name = "No name";
}
public Employee(int id, String name)
{
this.id = id;
this.name = name;
}

public void changeData(int id, String name)
{
this.id = id;
this.name = name;
}

public void print()
{
System.out.println("No : " + id);
}
}

public class PrintEmp
{
public static void main(String args[])
{
// Employee.description();
Employee emp1 = new Employee(1,"Tanaka");
System.out.print("Name : " + emp1.name);
emp1.print();
System.out.print("Name : " + emp1.name);
Employee emp2 = new Employee();
emp2.print();
System.out.print("Name : " + emp1.name);
emp2.changeData(5,"Yamada");
emp2.print();
System.out.print("Name : " + emp1.name);
}
}

一般的函数有两个修辞语:
访问控制、返回类型
比如:public void fun1()
private int fun2()
要是你不知道应该返回什么,或者感觉没必要干返回什么,就用void

另外说一下返回类型
一般情况,返回类型是什么,就要在函数里有返回语句 return 返回类型
比如上面的 fun2() 就要有 return (int)变量
void的话就可以不用return