display data java from arraylist in column

Question

I would like to know how am I supposed to get the elements from a arraylist in a column(under each other) like this:

BMI:   Length:   gewicht:
1.69       30     24.25
2.58       55     28.25

This is my code:

 @Override
    public String toString() {
        return String.format("%-17.1f%-15.2f%.2f",lengte, gewicht,bmi);        
        
    }


    public static void main(String[]args){
        ArrayList<BMICalculator> bmilist = new ArrayList<>();
JOptionPane.showMessageDialog(null, String.format("length:%-9sgewicht:%-8sbmi:","","") );

        do {
            double lengte = getLength("Geef de lengte in Meters:");
            double gewicht = getGewicht("Geef het gewicht in Kg:");
            BMICalculator bmi = new BMICalculator(lengte, gewicht);
            bmi.setBmi(bmi.calculateBMI());
            bmilist.add(bmi);           
            
            JOptionPane.showMessageDialog(null, String.format("%s", bmi.toString()));
        } while(getUserAnswer() == 'J');

        JOptionPane.showMessageDialog(null,  String.format("%s", bmilist.toString()));
        System.out.println(bmilist);

    }

This code gives me this: length: gewicht: Bmi: 1,7 80,00 28,01, length: gewicht: bmi: 1,6 55,00 22,03

I dont want that length, gewicht and bmi keeps repeating... help!!!

yes, I get the data under each other but the words length, gewicht and BMI keeps repeating... — Pedro Costa
– Pedro Costa, Commented Sep 29, 2020 at 19:15
Does this answer your question? Java String Formatting (Columns) — Polygnome
– Polygnome, Commented Sep 30, 2020 at 13:50

Mauricio Guzinski · Accepted Answer · 2020-09-30 13:46:48Z

1

Your header and data are merged together in that String.format mask. That's why the header keeps repeating. You'll need to separate them. So use String.format("length:%-9sgewicht:%-8sbmi:","","") to print the header once, before the loop. And for each line of data use String.format("%-17.1f%-15.2f%.2f",lengte, gewicht,bmi). That way I think you will be fine.

But, if what you want is the whole text into the same pane, it would be something like this:

public static void main(String[] args) {
    StringBuilder sb = new StringBuilder();
    ArrayList<BMICalculator> bmilist = new ArrayList<>();
    
    sb.append(String.format("length:%-9sgewicht:%-8sbmi:\n", "", ""));

    do {
        double lengte = getLength("Geef de lengte in Meters:");
        double gewicht = getGewicht("Geef het gewicht in Kg:");
        BMICalculator bmi = new BMICalculator(lengte, gewicht);
        bmi.setBmi(bmi.calculateBMI());
        bmilist.add(bmi);

    } while (getUserAnswer() == 'J');
    
    for (BMICalculator item : bmilist) {
        sb.append( item.toString() );
    }
    
    JOptionPane.showMessageDialog(null, sb.toString());
    
    System.out.println(bmilist);
}

edited Sep 30, 2020 at 13:46

answered Sep 29, 2020 at 19:21

Mauricio Guzinski

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6 Comments

Mauricio Guzinski Over a year ago

"String.format("%-17.1f%-15.2f%.2f",lengte, gewicht,bmi)" should be the one in your "toString()" method. "String.format("length:%-9sgewicht:%-8sbmi:","","")" inside the "main" method in your example, before the "do {" line

Mauricio Guzinski Over a year ago

Please, keep in mind that, for your case, the "toString" method cannot solve everything. The header line must be printed outside the "toString" method. The System.out.println( String.format("length:%-9sgewicht:%-8sbmi:","","") ); will certainly print the header. Place it any where before start the loop.

Pedro Costa Over a year ago

I putted: String.format("length:%-9sgewicht:%-8sbmi:","","") inside the "Tostring" and one line before the "Do", I added...JOptionPane(null, String.format("length:%-9sgewicht:%-8sbmi:","","") );.... But it still doesnt work...

Pedro Costa Over a year ago

I cant send the whole code through here... Can I send it to you?

Pedro Costa Over a year ago

Maurizio, just edited my question with those 2 lines you told me to add.

|

A G · Accepted Answer · 2020-10-05 16:52:23Z

import java.util.*;

public class Main {


static class Friend {
String name;
int age;
String phone;

public Friend(String name, int age, String phone) {
  this.name = name;
  this.age = age;
  this.phone = phone;
}

@Override
public String toString() {
return String.format("%-15s %-4s %10s", name, "" + age, phone);
}
}

public static void main(String[] args) {

ArrayList<Friend> friends = new ArrayList();
friends.add(new Friend("F11", 12, "phone11"));
friends.add(new Friend("F21", 21, "phone21"));
friends.add(new Friend("F321", 123, "phone321"));
printFriends(friends);
}

private static void printFriends(ArrayList<Friend> friends) {
printHeader() ;
friends.forEach(friend -> System.out.println(friend.toString()));
}

private static void printHeader() {

System.out.println(String.format("%-15s %-4s %10s","Name","Age", "Phone"));

}

}

Output:

Name            Age       Phone
F11             12      phone11
F21             21      phone21
F321            123    phone321

Play with String format and spacing to get desired column spacing.

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