Java Class - Array println

Question

i have 2 Class, the first class College and the second Lecturer. in College class i have >> public Lecturer[] allLecturer;

I want the college department will receive the Lecturer department, But I have something strange when I try to print the college department.

class Lecturer:

public class Lecturer {
public String name;
public int numOfTimesPenFalls;
public String favoriteIceCream;
public int autoNumber;

//constructor
public Lecturer(String Name, int NumOfTimesPenFalls,
        String FavoriteIceCream, int AutoNumber) {
    this.name = Name;
    this.numOfTimesPenFalls = NumOfTimesPenFalls;
    this.favoriteIceCream = FavoriteIceCream;
    this.autoNumber = AutoNumber;
}

@Override
public String toString(){
    return "name: " +name+ " num Of Times Pen Falls: "+ numOfTimesPenFalls +
    " favorite Ice Cream: " + favoriteIceCream + " auto Number: " + autoNumber;
}
}

class College:

public class College {
public String name;
public int numOfLecturer;
public Lecturer[] allLecturer;
public int maxLecturer;

//constructor
public College(String Name, int NumOfLecturer, Lecturer[] AllLecturer, int MaxLecturer) {
    this.name = Name;
    this.numOfLecturer = NumOfLecturer;
    this.allLecturer = AllLecturer;
    this.maxLecturer = MaxLecturer;
}

public College(String Name){
    this.name = Name;
}

@Override
public String toString(){
    return "Name College: " +name+ " num Of Lecturer: " + numOfLecturer + 
    " all Lecturer: " + allLecturer + " max Lecturer " + maxLecturer ;
}
}

main:

public class main {
public static void main(String[] args) {

    Lecturer[] L1 = new Lecturer[] { new Lecturer("David", 3, "Banana",
            1001) };

    College myCollege = new College("College1", 20, L1, 10);

    System.out.println(myCollege.toString());

}
}

Result output:

Name College: College1 num Of Lecturer: 20 all Lecturer: [LLecturer;@139a55 max Lecturer 10

Why it prints me the ([LLecturer;@139a55) Instead the details of the department?

If I write in main for loop:

for (int i = 0; i < L1.length; i++) {
        System.out.println(L1[i]);
    }

the Result output:

 name: David num Of Times Pen Falls: 3 favorite Ice Cream: Banana auto Number: 1001

How do I fix this so that when I print the class College (System.out.println(myCollege.toString()) );
I also printed the information that is in the lecturer Department?

thank you.

Answer 1

hey when you concat an array with string it will use his toString function. the default toString function will print something like you see in your code. the toString of a single object in the array will print what you want .

Answer 2

Java arrays do not override Object 's toString() method. just add the loop that you wrote to the toString() method of College

example solution:

@Override
public String toString(){
    return "Name College: " +name+ " num Of Lecturer: " + numOfLecturer + 
    " all Lecturer: " + java.util.Arrays.toString(allLecturer) + " max Lecturer " + maxLecturer ;
}

and if you can use 3rd party library, take a look at Apache's StringUtils class, it has a handy join() method that produces a String from concatanating array of objects

Answer 3

change your toString() method in College.java to

@Override
public String toString(){
    return "Name College: " +name+ " num Of Lecturer: " + numOfLecturer + 
    " all Lecturer: " + Arrays.toString(allLecturer) + " max Lecturer " + maxLecturer ;
}

and in your main method try to print your College reference

College myCollege = new College("College1", 20, L1, 10);
System.out.println(myCollege);

now your output is:

Name College: College1 num Of Lecturer: 20 all Lecturer: [name: David num Of Times Pen Falls: 3 favorite Ice Cream: Banana auto Number: 1001] max Lecturer 10