java - 创建方法和对象

Question

大家好，我得到了这个驱动程序类，并被告知要创建类以使驱动程序类正常工作。在大多数情况下，我认为我走在正确的轨道上，但我又不完全确定，因为我是 java 新手。我收到 2 个编译错误，因为我没有添加 add(temp) 方法。老实说，我不确定将该方法放入哪个类中。现在我在 Team 类中有它，但我收到编译错误。如果有人能给我一些见解，我将不胜感激。

public class Driver{
 public static void main(String args[]) throws Exception{
    //All information is stored in input.txt and is being
    //read in below.
    Scanner input = new Scanner(new File("input.txt"));
    //Creates a new League and passes in a String signifying
    //which league it is.
    League american = new League("AL");
    League national = new League("NL");
    for(int i=0; i<15; i++){
        //Creates a new team and adds the current team
        //to the american league.
        //You can assume there are exactly 15 teams in each league.
        Team temp = new Team(input.next());
        american.add(temp);   // compile error
    }
    for(int i=0; i<15; i++){
        //Creates a new team and adds the current team
        //to the national league.
        //You can assume there are exactly 15 teams in each league.
        Team temp = new Team(input.next());
        national.add(temp);   // compile error 
    }
    }

我的联赛类(class)

public class League{
private String league;

public League(String League){
     league = League;
}

public void setLeagueAmerican(String League){
    this.league = League;
}

public String getLeagueAmerican(){
    return league;
}

public void setLeagueNational(String national){
    this.league = national;
}

public String getLeagueNational(){
    return league;
}


public void League( String League){

     league = League;

}
}

我的团队类(class)

public class Team
{
// instance variables - replace the example below with your own
private String team;

/**
 * Constructor for objects of class Team
 */
public Team(String Team)
{
    team = Team;
}

public void setTeam(String Team){
    this.team = Team;
}

public String getTeam(){
    return team;
}



public String add(League y)
{

    return y;       //compiling error 
}
}

Answer 1

public String add(League y)
{
    return y;       //compiling error 
}

该函数返回 String 。您正在传递参数 y ，这是 League 。然后，您尝试返回完全相同的 League就好像它是 String ，这会产生错误。

将返回类型更改为 League ，或者不返回 y但一个有意义的字符串(甚至 y.toString() )