arraylisttoarray.java

java2参考大全上的例子的源码和自己的理解.

package 将arraylist转换成数组;

/**
 该程序的输出如下所示：

 Contents of al: [1, 2, 3, 4]
 Sum is: 10
 */

// Convert an ArrayList into an array.
import java.util.*;

class ArrayListToArray {
  public static void main(String args[]) {
    // Create an array list
    ArrayList al = new ArrayList();

    // Add elements to the array list
    al.add(new Integer(1));
    al.add(new Integer(2));
    al.add(new Integer(3));
    al.add(new Integer(4));

    System.out.println("Contents of al: " + al);

    // get array
    Object ia[] = al.toArray();
    int sum = 0;

    // sum the array
    for (int i = 0; i < ia.length; i++) {
      sum += ( (Integer) ia[i]).intValue();

    }
    System.out.println("Sum is: " + sum);
  }
}