public class Song{

  protected String title;
  private int time; // the playing time
  
  public Song(String title, int time){
    this.title=title;
    this.time=time;
  }
  
  // Determine if the total playing time 
  // for this and the two given songs is 10
  public boolean tenMinutesTotal(Song two, Song three){
    return this.time + two.time + three.time == 10;
  }
  
  // Is the playing time for this song shorter than for that song?
  private Song shorter(Song that){
    if (this.time < that.time)
      return this;
    else
      return that;
  }
} 

// Tests:
class Examples{
Song song1 = new Song("title1", 4);
Song song2 = new Song("title2", 2);
Song song1a = new Song("title1", 4);

public void testMethods(Tester t){
  // test this.song1.shorter(this.song2) -- expect song1
  t.checkExpect("Check if you get the shorter song -- should fail",
                this.song1,       // expected value
                this.song1,       // object that invokes the method
                "shorter",        // method name
                this.song2);      // method arguments

  // test song1.tenMinutesTotal(song1a, song2) -- expect true
  t.checkExpect("Check if the total playing time is 10 -- should succeed",
                true                       // expected value
                this.song1,                // object that invokes the method
                "tenMinutesTotal",         // method name
                this.song1a, this.song2);  // method arguments
}}

class CartPtDouble{
  double x;
  double y;

  CartPtDouble(double x, double y){
    this.x = x; this.y = y;
  }

  // compute the distance from this point to the origin
  double distTo0(){
    return Math.sqrt(this.x * this.x + this.y * this.y);
  }
  
  // compute the distance to the given point
  double distTo(CartPtDouble that){
    return Math.sqrt((this.x - that.x) * (this.x - that.x) + 
    		     (this.y - that.y) * (this.y - that.y));
  }
}

class Examples{
  Examples(){}

  void testMethodInvocation(Tester t){
  	t.checkMethod("exact - will succeed", 5.0, this.pt, "distTo0");
  	t.checkInexactMethod("inexact check - success",
  		   	     4.998,
  			     0.001,
  			     this.pt,
  			     "distTo", 
  			     new CartPtDouble(7.0, 7.0));  	
  }
}