Listex

public class Listex {
    
  static int[] a;  
   
  public static void main(String[] arg) {
    System.out.println("listex starts");
    
    // create and initialise an array a
      
    a=new int[5];
    a[0]=10;
    a[1]=20;
    a[2]=30;
    a[3]=40;
    a[4]=50;      
          
    for(int i=0; i<a.length; i++) {
       System.out.println("a elem "+i+" is: "+a[i]); 
    }        
    
    // build a new list from array a, storing start at ls
    
    Listnode ls=null; // list start
    Listnode ln=null; // current (temporary) list node
    Listnode lp=null; // previous (temporary) list node
    for(int i=0; i<a.length; i++) {
      ln=new Listnode();
      if (i==0) ls=ln;  
      ln.data=a[i];
      ln.next=null;          
      if (lp!=null) lp.next=ln;
      lp=ln;          
    }
    
    // go through the list, print out all data, count els
    
    int count=0;
    for(ln=ls; ln!=null; ln=ln.next) {
      count++;  
      System.out.println("node data: "+ln.data);        
    }    
    
    // go through the list and store data to a new array
    
    int[] b;
    b=new int[count];    
    count=0;    
    for(ln=ls; ln!=null; ln=ln.next) {
      b[count]=ln.data;  
      count++;              
    }
    
    
    // go thorugh array b and print els
    
    for(int i=0; i<b.length; i++) {
       System.out.println("b elem "+i+" is: "+b[i]); 
    }  
    
    // add a new node containing 100 
    // after el containing 30
    
    Listnode nn;
    for(ln=ls; ln!=null; ln=ln.next) {
      if (ln.data==30) {
        nn=new Listnode();
        nn.data=100;           
        nn.next=ln.next;
        ln.next=nn;
        break;                
      }                  
    } 
    
    ls.listprint();    
    
    System.out.println("listex ends");  
  } 



}  

class Listnode {
  int data;   
  Listnode next; 
      
int listprint() {
  // go through the list, print out all data, count els
  
  Listnode ln;
    
  int count=0;
  for(ln=this; ln!=null; ln=ln.next) {
    count++;  
    System.out.println("node data: "+ln.data);        
  }    
  return count;       
}    
}