数组的相关操作--------孙鑫视频

[猪小烧]

import java.util.Arrays;

class ArrayTest
{
public static void main(String[] args)
{
int[] num1 = new int[]{1,2,3};
int[] num2 = new int[3];
int[] num3 = new int[10];

System.arraycopy(num1,0,num2,0,num1.length);
for (int i = 0; i < num2.length; i++)
{
System.out.println(num2[i]);
}

System.arraycopy(num1,1,num3,8,2);
for (int i = 0; i < num3.length; i++)
{
System.out.println(num3[i]);
}

Point[] pts1 = new Point[]{new Point(1,1),new Point(2,2),new Point(3,3)};
Point[] pts2 = new Point[3];
System.arraycopy(pts1,0,pts2,0,pts1.length);
for (int i = 0; i < pts2.length; i++)
{
System.out.println("x="+pts2[i].x+",y="+pts2[i].y);
}

pts2[1].x = 5;
pts2[1].y = 5;
System.out.println("x="+pts1[1].x+",y="+pts1[1].y);

int[] num4 = new int[]{3,1,2};
Arrays.sort(num4);
for (int i = 0; i < num4.length; i++)
{
System.out.println(num4[i]);
}

int index = Arrays.binarySearch(num4,3);
System.out.println("index="+index);
System.out.println("element="+num4[index]);
Student[] ss = new Student[]{new Student("zhangsan",3),new Student("lisi",2),new Student("wangwu",1)};
Arrays.sort(ss);

for (int i = 0; i < ss.length; i++)
{
System.out.println(ss[i]);
}
}
}

class Point
{
int x,y;
Point(int x,int y)
{
this.x = x;
this.y = y;
}
}

class Student implements Comparable
{
int num;
String name;

Student(String name,int num)
{
this.num = num;
this.name = name;
}

public String toString
{
return "number="+num+",name="+name;
}

public int compareTo(Object o)
{
Student s = (Student)o;
return num > s.num ? 1 : (num == s.num ? 0 : -1);

}

}

return num > s.num ? 1 : (num == s.num ? 0 : -1);这个不理解
不是三元表达式不理解
而是 num > s.num ? 1 这里的num是什么？
是传过来的num吗？那么他和s.num不是恒相等的吗？

[猪小烧]

传过来的对象不就是当前对象吗？

[jianfengqu]

num是当前对象里的，若是这样写你就更明白了：this.num。而你看Student s = (Student)o，说明s是通过参数传过来的另一个对象了。