Brief probe into arrayList

Today let us brief talk about the array.Array which can be seen in every corner in our programing world and what are its advantages and shortcomings.Hava you really thought about it.

Its adavantages:

1.You can create many objects in one time, in other words you can save time to do other things.

2.You can reach the object you want quikly according to the index.

3.Array is address reference.

4.Array has its center number so it is easily to check ArrayIndexOutOfBoundsException.

Its shortcomings:

1.Array has its center number. When you not sure how many objects you want to create,this advantage turn into a shortcoming

 

Here is some array Sorting algorithm, when i finished it, i felt i had mastered the array.

package 数组排序;

import java.util.Arrays;

public class Array {
	int[] a=new int[]{0,5,3,7,46};
	
	
	public static void main(String[] args){
		Array test=new Array();
		
	int[] a=new int[]{0,5,3,7,46};
	int MAX=0;
	//bubble sort
	for(int i=0;i<5;i++){
		
		for(int j=i;j<5;j++){
			if(a[i]<a[j])
			{
				int temp;
				temp=a[i];
				a[i]=a[j]; 
				a[j]=temp;
			}
		} 
	}
	
	for(int i=0;i<5;i++){
		System.out.print(a[i]+"   ");
	}
	test.select();
	test.arrays();
	test.insert();
	test.shell();
	}
	//selection sorting
          public void select(){
        	  System.out.println();
		for(int i = 0;i<a.length;i++)
		{
			int lowerIndex=i;
			//find the min index
			for(int j=i+1;j<a.length;j++){
				if(a[j]<a[lowerIndex])
				{lowerIndex=j;}
			}
			//exchange
			int temp=a[i];
			a[i]=a[lowerIndex];
			a[lowerIndex]=temp;
		}
		
		for(int i=0;i<5;i++){
			System.out.print(a[i]+"   ");
		}
	    }
          
        //which method has saved in JDK 
      	public void arrays(){
      		System.out.println();
      		Arrays.sort(a);
      		for(int i=0;i<5;i++){
    			System.out.print(a[i]+"   ");}
      		
      	}
        //insertion sorting
          public void insert(){
        	  System.out.println();
        	  for(int i=1;i<a.length;i++){
        		  for(int j=i;j>0;j--){
        			  if(a[j]<a[j-1]){
        				  int temp=a[j];
        				  a[j]=a[j-1];
        				  a[j-1]=temp;
        			  }
        		  }
        	  }
        	  for(int i=0;i<5;i++){
      			System.out.print(a[i]+"   ");}
          }
          //shell sorting
          public void shell(){
        	  System.out.println();
        	  //divide into group
        	  for(int increment=a.length/2;increment>0;increment/=2){
        		  //sort in each group
        		  for(int i=increment;i<a.length;i++){
        			  int temp=a[i];
        			  int j=0;
        			  for(j=i;j>=increment;j-=increment){
        				  if(temp<a[j-increment])
        				  {
        					  a[j]=a[j-increment];
        				  }else
        					  break;
        			  }
        			  a[j]=temp;
        		  }
        	  }
        	  
        	  for(int i=0;i<5;i++){
        			System.out.print(a[i]+"   ");}
          }
          
          
}