array list

      As my last BLOG had metioned, array has it shortcoming it has range and it can grow.It is awful to think about it.To solve this problem ,we need a powerful method to deal with it.So the arrayList appear in my sight.

      Array's name represent its location in the Rom.So you can replace your last array with a new one.It's cool ,isn't it.Use this method we can solve the problem we have listed above.

      First we should define a array interface,which is like this

package xy_队列0730;

/**
 * define my arrayList
 * @author Administrator
 *
 */
public interface NetJavaList {
	//add a student object to my List
	public void add(student st);
	//get the student from a certain location 
	public student get(int index);
	//get the length of the array
	public int size();
}

 second we just need to  implements the interface  then we can get a array which can grow.

package xy_队列0730;

public class STList implements NetJavaList{

	@Override
	public void add(student st) {
		//define a new list ,which length is source List length + 1
		student[] destA=new student[srcA.length+1];
		//add the new object to the last of the new array
		destA[srcA.length]=st;
		//add source array to the new array
		for(int t=0;t<srcA.length;t++){
			destA[t]=srcA[t];
		}
		//point at new array
		srcA=destA;
	}

	public student get(int index) {
		student st=srcA[index];
		return st;
	}

	public int size() {
		return srcA.length;
	}
	//initialize the array to accept the student object in the list,which length is 0 
	private student[] srcA =new student[0];
	}

 But if you want to store another type array,then you have to define another arrayList.So to avoid the situation clever programmer define the genericity which is helpful. Genericity which can represent every type it is just a name.It just like a formwork.

package xuyi_java_0717;
/**
 * i define the Genericity(泛型) arrayList 
 * @author Administrator
 *
 */
public interface Genericity<E> {
	//add a object to the arrayList
	public void add(E e);
	//get a object from a certain index 
	public E get(int index);
	//get the length of the arrayList 
	public int size();
}

 

package xuyi_java_0717;

/**
 * define the genericity arrayList
 * @author Administrator
 *
 */
public class Igenericity<E> implements Genericity{
	//define a arrayList in the arrayList to store the object which length is 0
	//Object is the superclass of all the class
	private Object[] srcA=new Object[0];
	public void add(Object e) {
		//create a new array which length is source length +1
		Object[] destA=new Object[srcA.length+1];
		//add the new object to the last location
		destA[srcA.length]=e;
		//use the method to copy the array
		System.arraycopy(srcA, 0, destA, 0, srcA.length);
		//point at the new create array
		srcA=destA;
	}

	public E get(int index) {
		E st=(E)srcA[index];
		return st;
	}

	public int size() {
		return srcA.length;
	}

}

 

Now we can make our repainting and storing every step of gobang come ture.