Question

WRITE MODULES TO SORT BY 2 FIELD THEN 3 FIELD, THEN 4 FIELD use data structure to guide you. please i need help. im so glad if anyone help me. thank you a lot and be safe

// Use a custom comparator.
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;

class Emprec {
String name;
String address;
double hours;
double rate;
int dependents;
char gender;
boolean degree;

// This is the classes's constructor !!!!

Emprec(String name, String address, String hours,String dependents) {

try {
this.name = name;
this.address = address;
this.hours = Double.valueOf(hours).doubleValue();
this.dependents = Integer.parseInt(dependents);
} catch (NumberFormatException errmsg) {
System.out.println("Invalid format" + errmsg);

this.name = "";
this.hours = 0.0;

}// catch

}// Emprec constructor !!!!

double calc_fed_tax(double hours, double rate) {

double yearly_income;

yearly_income = hours * rate * 52;

if (yearly_income < 30000.00)
return (hours * rate * .28);

else if (yearly_income < 50000.00)
return (hours * rate * .32);

else
return (hours * rate * .38);

}// calc_fed_tax

double calc_state_tax(double hours, double rate) {

double state_tax;

state_tax = hours * rate * .0561;

return (state_tax);

}// calc_state_tax

public void setName(String name) {
this.name = name;
}

public String getName() {
return name;
}

public String getAddress() {
return address;
}

public double getHours() {
return hours;
}

public int getDependents() {
return dependents;
}
   
    public double getRate(){
        return rate;
    }
   
    public char getGender(){
        return gender;
    }

public String toString() {

return ("\n Name:    " + name +
"\n Address: " + address +
"\n Hours:   " + hours+
"\n Dependents " + dependents);

}// toString
}// Emprec

public class CompDemo3Sorts_Improved {
public static void main(String args[]) throws IOException {
// Create a tree set
BufferedReader inData = new BufferedReader(new InputStreamReader(
System.in));

// create strings for the input data for the Emprec object
String str_name;
String str_address;
String str_hours;
String str_dependents;

TreeSet<Emprec> ts = new TreeSet<Emprec>(new MyCompHours());// eclipse ask for casting
for (;;) {
System.out.print(" name:    ");
str_name = inData.readLine();

if (str_name.equalsIgnoreCase("exit")) break;

System.out.print(" Address: ");
str_address = inData.readLine();

System.out.print(" Hours:   ");
str_hours = inData.readLine();

System.out.print(" Dependents:   ");
str_dependents = inData.readLine();

Emprec employee = new Emprec(str_name, str_address, str_hours,str_dependents);

ts.add(employee);
}// for

// Get an iterator
Iterator<Emprec> i = ts.iterator();

// Display elements
while (i.hasNext()) {
Object element = i.next();
System.out.print(element + "\n");// calls the toString()
}//while
System.out.println();
}
}

class MyCompName implements Comparator<Object> { // eclipse ask for casting object
public int compare(Object emp1, Object emp2) {

String emp1Name = ((Emprec) emp1).getName();

String emp2Name = ((Emprec) emp2).getName();

return ((emp2Name.compareTo(emp1Name) <= 0) ? -1 : +1);

}
}


class MyCompHours implements Comparator<Object> { // eclipse ask for casting object
public int compare(Object emp1, Object emp2) {

double emp1Hours = ((Emprec) emp1).getHours();

double emp2Hours = ((Emprec) emp2).getHours();


return (emp1Hours <= emp2Hours)? -1:+1;
}
}


class MyCompAddress implements Comparator<Object> { // eclipse ask for casting object
public int compare(Object emp1, Object emp2) {

String emp1Address = ((Emprec) emp1).getAddress();

String emp2Address = ((Emprec) emp2).getAddress();


return ((emp2Address.compareTo(emp1Address) <= 0) ? -1 : +1);

}
}


class MyCompRate implements Comparator<Object>{
    public int compare(Object emp1, Object emp2){
        double emp1Rate = ((Emprec) emp1).getRate();
        double emp2Rate = ((Emprec) emp2).getRate();

        return ((emp1Rate <= emp2Rate) ? -1 : +1);
    }
}


class MyCompDependents implements Comparator<Object>{
    public int compare(Object emp1, Object emp2){
        int emp1Dependents = ((Emprec) emp1).getDependents();
        int emp2Dependents = ((Emprec) emp2).getDependents();

        return ((emp1Dependents <= emp2Dependents) ? -1 : +1);
    }
}


class MyCompGender implements Comparator<Object>{
    public int compare(Object emp1, Object emp2){
        char emp1Gender = ((Emprec) emp1).getGender();
        char emp2Gender = ((Emprec) emp2).getGender();

        return ((emp1Gender <= emp2Gender) ? -1 : +1);
    }
}

WRITE MODULES TO SORT BY 2 FIELD THEN 3 FIELD, THEN 4 FIELD use data structure to guide you. please i need help. im so glad if anyone help me. thank you a lot and be safe

Answer 1

I am using java 8 .. it will work .. please refer my code for multiple sorting.....

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.stream.Collectors;

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

       // Create a tree set
       BufferedReader inData = new BufferedReader(new InputStreamReader(
               System.in));

       // create strings for the input data for the Emprec object
       String str_name;
       String str_address;
       String str_hours;
       String str_dependents;

       ArrayList<Emprec> list = new ArrayList<Emprec>();// eclipse ask for casting
       for (;;) {
           System.out.print(" name: ");
           str_name = inData.readLine();

           if (str_name.equalsIgnoreCase("exit")) break;

           System.out.print(" Address: ");
           str_address = inData.readLine();

           System.out.print(" Hours: ");
           str_hours = inData.readLine();

           System.out.print(" Dependents: ");
           str_dependents = inData.readLine();

           Emprec employee = new Emprec(str_name, str_address, str_hours,str_dependents);

           list.add(employee);
       }          
       //name comparator
       Comparator<Emprec> compareByName = Comparator.comparing( Emprec::getName );
       //Address comparator
       Comparator<Emprec> compareByAddress = Comparator.comparing( Emprec::getAddress );
       //hours comparator
       Comparator<Emprec> compareByhours = Comparator.comparing( Emprec::getHours );
       //Dependent comparator
       Comparator<Emprec> compareByDependent = Comparator.comparing( Emprec::getDependents );

       //Compare by first name and then last name (multiple fields)
       Comparator<Emprec> compareByFullName = compareByName.thenComparing(compareByAddress)
               .thenComparing(compareByhours).thenComparing(compareByDependent);
       //Using Comparator - pseudo code
       List<Emprec> sortedEmployees = list.stream()
               .sorted(compareByFullName)
               .collect(Collectors.toList());

       // Get an iterator
       Iterator<Emprec> i = sortedEmployees.iterator();

       // Display elements
       while (i.hasNext()) {
           Object element = i.next();
           System.out.print(element + "\t");// calls the toString()
       }//while
       System.out.println();

   }

}

output :

name: Arjun
Address: Hys
Hours: 12
Dependents: 3
name: Arun
Address: Gan
Hours: 42
Dependents: 13
name: Rajesh
Address: Sec
Hours: 76
Dependents: 45
name: Ganesh
Address: Bangalore
Hours: 23
Dependents: 23
name: exit

Name: Arjun
Address: Hys
Hours: 12.0
Dependents 3  
Name: Arun
Address: Gan
Hours: 42.0
Dependents 13  
Name: Ganesh
Address: Bangalore
Hours: 23.0
Dependents 23  
Name: Rajesh
Address: Sec
Hours: 76.0
Dependents 45