Problems with sort swimmers

[Felissa]

I'm in an intro to comp sci class and I came across a problem I can't figure out.

I have to write a program which will take the names and times for three swimmers during a 50-m free style.

The program has to sort out their times from fastest to slowest. Its in the chapter for if statements so I need to sort out the times using if statements, but I can't seem to figure out how.

My problem is I just can't figure out the logic, what to use for the if statements.

Code:

import java.util.Scanner;

public class SwimmerTimes
{
    public static void main(String[] args)
	 {
	     String swimmer1_name;
		  String swimmer2_name;
		  String swimmer3_name;
		  
		  String first;
		  String second;
		  String third;
		  
		  float swimmer1_time;
		  float swimmer2_time;
		  float swimmer3_time;
		  
		  Scanner keyboard = new Scanner(System.in);
		  
		  // swimmer 1
		  System.out.println("Please enter the first swimmer's name:");
		  swimmer1_name = keyboard.nextLine();
		  System.out.println("please enter the first swimmer's time:");
		  swimmer1_time = keyboard.nextFloat();
		  
		  // swimmer 2
		  System.out.println("Please enter the second swimmer's name:");
		  swimmer2_name = keyboard.nextLine();
		  System.out.println("please enter the second swimmer's time:");
		  swimmer2_time = keyboard.nextFloat();
		  
		  // swimmer 3
		  System.out.println("Please enter the third swimmer's name:");
		  swimmer3_name = keyboard.nextLine();
		  System.out.println("please enter the third swimmer's time:");
		  swimmer3_time = keyboard.nextFloat();
		  
		  if (swimmer1_time < swimmer2_time && swimmer2_time < swimmer3_time)
		  {
		      first = swimmer1_name;
				second = swimmer2_name;
				third = swimmer3_name;
		  }
		  else if (swimmer2_time < swimmer1_time && swimmer1_time < swimmer3_time)
		  {
		      first = swimmer2_name;
				second = swimmer3_name;
				third = swimmer1_name;
		  }
		  else if (
	 }
}

Thanks

Felissa

[Marcus]

Will the input always be three swimmers? If it's always three swimmers then you can do any number of sorts the brute force way.

Or you could just do a mass comparison, figuring out which spot goes where.

Code:

 if(swim1 > swim2)
    if(swim1 > swim3) // swim1 = biggest
      if(swim2 > swim3) // swim3 smallest, swim2 middle, swim1 last
      else // swim3 middle, swim2 smallest, swim 1 last
    else  //swim 1 = second, swim3 largest, swim2 smallest
  else
    if(swim 1 > swim3) //swim 1 second, swim 3 first, swim2 last
    else  // swim1 = first
      if(swim 2 > swim3) // swim1 first, swim2 last swim3 second
      else  // swim1 first, swim2 second, swim3 last

Or something like that. I have NO clue if that is completely correct, but you could debug through the logic yourself and figure it out.

Greetings

Marcus

[Eric]

The following solution might be an advanced solution for you...but since you are learning Java, I am sure that sooner or later...you will come across Classes, Arrays, etc.

The following is a class that defines Simmer and should be saved in "Simmer.java" file

Code:

public class Simmer {
    
    private String name; // simmer name
    private float time; // simmer age
    
    // default constructor
    public Simmer() {
    }
    
    public Simmer( final String name, final float time ) {
        this.setName( name );
        this.setTime( time );
    }
    
    public void setName( final String name ) {
        if( "".equals( name ) ) {
            // throw exception or try and ask user to enter name agin
        } else {
            this.name = name;
        } //-- ends else
    } //-- ends setName
    
    public String getName() {
        return this.name;
    } //-- ends getName
    
    public void setTime( final float time ) {
        if( time <= 0 ) {
            // throw exception...or ask user to enter time again
        } else {
            this.time = time;
        } //-- ends else
    } //-- ends setTime
    
    public float getTime() {
        return this.time;
    } //-- ends instance method getTime
     
    public String toString() {
        return "Name: " + this.name + "\tTime: " + this.time;
    } //-- ends toString
        
} //-- ends class definition

The following is a class that has a main method, which glue everything together. Save this file in SimmerRunner.java

Code:

public class SimmerRunner {
    public static void main( String [] args ) {
        
        // get the input from user as you have done in your sample
        // and then populate the array as shown below
        Simmer [] simmerCollection = new Simmer[3];
        simmerCollection[0] = new Simmer( "John Smith", 145.11f );
        simmerCollection[1] = new Simmer( "Mark DoLittle", 138.28f );
        simmerCollection[2] = new Simmer( "John Summer", 145.45f );
        
        // print all simmer as they have been entered
        System.out.println("-------- Simmers Entered Competition -------");
        for( int i = 0; i < simmerCollection.length; i++ ) {
            System.out.println(simmerCollection[i].toString());
        } //-- ends for loop
        
        // now, we have to loop through the array twice using if statement
        // to establish who finished first
        for( int i = 0; i < simmerCollection.length; i++ ) {
            for( int j = 0; j < simmerCollection.length - 1; j++ ) {
                // we use if statements to check the finishing times
                if( simmerCollection[j].getTime() > simmerCollection[j+1].getTime() ) {
                    // if someone stored in posisiotn zero in the array finished
                    // after someone in position 1, we swap the reference in the array
                    Simmer temp = simmerCollection[j];
                    simmerCollection[j] = simmerCollection[j+1];
                    simmerCollection[j+1] = temp;
                    temp = null;
                } //-- ends if 
            } //-- ends inner for loop
        } //-- ends for loop
        
        // print all simmer as they have been entered
        System.out.println("\n---- Simmers Ordered by Finishing Time ----");
        for( int i = 0; i < simmerCollection.length; i++ ) {
            System.out.println(simmerCollection[i].toString());
        } //-- ends for loop
    } //-- ends class method main
} //-- ends class definition

once you have compiled the files, and executed SimmerRunner, the output should match the following:

Code:

-------- Simmers Entered Competition -------
Name: John Smith        Time: 145.11
Name: Mark DoLittle     Time: 138.28
Name: John Summer       Time: 145.45

---- Simmers Ordered by Finishing Time ----
Name: Mark DoLittle     Time: 138.28
Name: John Smith        Time: 145.11
Name: John Summer       Time: 145.45

Greetings

Eric