import java.util.*;
....
boolean[] a1 = new boolean[size];
Arrays.fill(a1, true);
...

package test.lang;
 
import java.util.Arrays;
 
public class ArrayFill
{
  public static final int ARRAY_SIZE = 10;
  public static final String TRUE = " true";
  public static final String FALSE = " false";
 
  public static void main (String[] args)
  {
    boolean[] b = new boolean[ARRAY_SIZE];
    show (b);
    Arrays.fill (b, true);    
    show (b);
  }
  
  public static void show(boolean[] aBooleanArray)
  {
    StringBuffer buf = new StringBuffer ();
    buf.append ('[');
    for (int i = 0; i < (aBooleanArray.length-1); i++) 
      buf.append ((aBooleanArray[i]?TRUE:FALSE)).append(',');
      
    buf.append (' ')
          .append (aBooleanArray[aBooleanArray.length-1])
          .append (']');
    
    System.out.println ("b[] = " + buf.toString ());
  }
}