Adding array of object into array list and compare with other array list based on one property value and filter the result

Question

Adding array of object into array list and compare with other array list based on one property value and filter the result.

I have an array of object personDetails and departmentDetails.

package com.education;

import java.util.*;

 public class educationMain {

 public static void main(String[] args) {
    
    List<person> list=new ArrayList<person>();  
    person l1 = new person(1,"Samual",100,"Sales","Business");
    person l2 = new person(2,"Alex",100,"Sales","Business");
    person l3 = new person(3,"Bob",101,"Engineering","Technology");
    person l4 = new person(4,"Michel",101,"Engineering","Technology");
    person l5 = new person(5,"Ryan",102,"PR","Services");
    person l6 = new person(6,"Horward",103,"Leadership","Managmnet");
    person l7 = new person(7,"Cyna",104,"HR","Human Resource");
    list.add(l1);  
    list.add(l2);  
    list.add(l3); 
    list.add(l4);  
    list.add(l5);  
    list.add(l6); 
    list.add(l7); 
    
     for(person b:list){  
            System.out.println(b.personId+" "+b.name+" "+b.deptCode+" "+b.parentDept+" "+b.deptName);  
     }  
     
     
     List<department> depList = new ArrayList<department>();
     
     department d1 = new department(100, "Sales","Business");
     department d2 = new department(101, "Engineering","Technology");
     department d3 = new department(102, "PR","Services");
     depList.add(d1);  
     depList.add(d2);  
     depList.add(d3); 

     for(department b:depList){  
            System.out.println(b.deptCode+" "+b.parentDept+" "+b.deptName);  
     }
}

}

So above code is working fine and displaying correctly.

My person class

package com.education;

public class person {
    public int personId;
    public String name;
    private int deptCode;
    private String parentDept;
    private String deptName;
    
    public person(int personId, String name, int deptCode, String parentDept, String deptName) {
        super();
        this.personId = personId;
        this.name = name;
        this.deptCode = deptCode;
        this.parentDept = parentDept;
        this.deptName = deptName;
    }
    
    public void display(){
         System.out.println(" " + personId + " " +name + " " + deptCode+ " " + parentDept + " "+deptName);
         System.out.println();
    }
    
}

My department class

public class department {
    
    private int deptCode;
    private String parentDept;
    private String deptName;
    public department(int deptCode, String parentDept, String deptName) {
        super();
        this.deptCode = deptCode;
        this.parentDept = parentDept;
        this.deptName = deptName;
    }
    
    public void dispalyDepartment() {
        System.out.println(" "+deptCode+" "+parentDept+" "+deptName);
    }

}

Now My goal is personDetails and departmentDetailsinto arraylist and compare and then findout the diference one bsed on dept code.

Here is my Logic : which is working fine.

List<person> listC = new ArrayList<person>();
         
         
         for(person p : list) {
             boolean  flag = false;
             for (department d:depList) {
                 if(p.deptCode == d.deptCode) {
                     flag = false;
                     break;
                 }else {
                     flag = true;
                 }
             }
             if(flag == true) {
                 listC.add(p);
             }
         }

o/p should be like

    (6,"Horward",103,"Leadership","Managmnet");
    (7,"Cyna",104,"HR","Human Resource");
    

because deptCode : 103 and 104 is not present.

Can anybody help me here. Can I use any other collection technique.

Answer 1

Try this.

    Set<Integer> deptCodes = Arrays.stream(departmentDetails)
        .map(department -> department.deptCode)
        .collect(Collectors.toSet());
    List<person> persons = Arrays.stream(personDetails)
        .filter(person -> !deptCodes.contains(person.deptCode))
        .collect(Collectors.toList());
    persons.forEach(person -> person.display());

output:

 6 Horward 103 Leadership Managmnet

 7 Cyna 104 HR Human Resource