int delay = 1000; //milliseconds ActionListener taskPerformer = new ActionListener() { public void actionPerformed(ActionEvent evt) { //...Perform a task... } }; new Timer(delay, taskPerformer).start();

because I need to notify me of a recurring event to perform a certain task each time interval.

1. class wavfile extends Minim {
3. String name=null;
4. //el constructor
5. wavfile(String name){
6.    this.name=name;
7.    super();
8.   }

1. import ddf.minim.*;
2. wavfile mywav;
3. setup(){
4. mywav=new wavfile("piano.wav");
5. }

2. class wavfile{
3.   
4. String name=null;
5. byte[] data=null;
6. 
   
7. 
   
8. //constructor
9. wavfile(String name){
10.   this.name=name;
11.   this.data= loadBytes(this.name);  
12.    
13.   }
14. 
    
15. //metadata
16. void lee_metadatos(){
17.    println(this.data.length);//<<<<<<<errror nullpointException
18.   }
19. 
    
20. }  

1. wavfile mywav=new wavfile("piano2.wav");
2. mywav.lee_metadatos();