Java的常用包之四

 

import java.util.*;
public class  ArrayTest
...{
     public static void main(String[] args)
     ...{
      //拷贝基本类型的数组和引用类型的数组
      /** *//**    int[] num1=new int[]{1,2,3};
          int[] num2=new int[10];
            System.arraycopy(num1,0,num2,8,num1.length);//这样的话会抛出一个RUNTIME异常，数组越界
            for(int i=0;i<num1.length;i++)           
            {  
               System.out.println(num1[i]);     
               System.out.println(num2[i]);  
           }      */
      
          /** *//**int[] num1=new int[]{1,2,3};
          int[] num2=new int[3];
            System.arraycopy(num1,0,num2,0,num1.length);
            for(int i=0;i<num1.length;i++)           
            {  
               System.out.println(num1[i]);     
               System.out.println(num2[i]);  
           }  */
                    
           /** *//**Point[] pt1=new Point[]{new Point(1,1),new Point(2,2),new Point(3,3)};
           Point[] pt2=new Point[3];
           System.arraycopy(pt1,0,pt2,0,pt1.length);//pt2是引用pt1拷贝
           for(int i=0;i<pt1.length;i++)
           {
           System.out.println("x=" + pt2[i].x +","+ "y=" + pt2[i].y);   
            }
            pt2[1].x=4;
            pt2[1].y=5;
            System.out.println("x=" + pt1[1].x +","+ "y=" + pt1[1].y); 
            //pt1[1].x=4,pt1[1].y=5，pt1是对象数组的引用，pt2只是pt1拷贝。
            */
            
            int[] num=new int[]...{1,2,3,8,7};
            Arrays.sort(num);
            for(int i=0;i<num.length;i++)
            ...{
                System.out.println(num[i]);
            }
            int index=Arrays.binarySearch(num,7);//必须是排序好的数
            System.out.println("index="+index);  
            System.out.println("num["+index+"]=" + num[index]);  
                 
      }
     
}
class Point
...{
    int x,y;
    Point(int x,int y)
    ...{
         this.x=x;
         this.y=y;
    }
}