Java每日一题（3）

题目：

使用java.lang.Math类，生成100个0到99之间的随机整数，找出它们之中的最大者和最小者，并统计大于50的整数个数

 

已有答案：

http://jythoner.javaeye.com/blog/322336?page=1#comments

 

另答：

/**
*    
*/
package math;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Random;

/**
* @author daniel zhou
*
*/
public class RandomTest {

   /**
    * Create 100 random numbers, get min & max number, sun up the number of >50
    * @param args
    */
   public static void main(String[] args) {
     /**
     * Here main show how to create an random number in some scope
    // get random by java.lang.Math
    double random = Math.random()*100;
    int in=(int) random;    
    System.out.println(random);
    System.out.println(in);
    // get random by java.util.Random
    Random ra=new Random();
    System.out.println(ra.nextInt(100));
    **/
    
     //create 100 random number
    ArrayList<Integer> arraylist= new ArrayList<Integer>();
    Random rand= new Random();
     int total_50=0;
     for ( int i = 0; i < 100; i++) {
       int num=rand.nextInt(100);
      arraylist.add(Integer.valueOf(num));
       //get number of >50
       if(num>50)total_50++;
    }
    System.out.println( "numbers of >50 is: "+total_50);
    
     //sort the arraylist
    Comparator<Integer> comp= new MyComparator();
    Collections.sort(arraylist, comp);
     //out min & max
    System.out.println( "Min number is: "+arraylist.get(0));
    System.out.println( "Max number is: "+arraylist.get(99));
    
  }
    
}

 

Comparator：

package math;

import java.util.Comparator;
/**
*    
* @author daniel zhou
*
*/
public class MyComparator implements Comparator<Integer>{

  @Override
   public int compare( final Integer o1, final Integer o2) {
     final Integer x=(Integer)o1;
     final Integer y=(Integer)o2;
     if (x>y) {
       return 1;
    } else{
       return 0;
    }
  }
    
}

 

或者将比较器写为一个内部类也是可以的，代码如下：

/**
*    
*/
package math;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Random;

/**
* @author daniel zhou
*
*/
public class RandomTest {

   /**
    * Create 100 random numbers, get min & max number, sun up the number of >50
    * @param args
    */
   public static void main(String[] args) {

    
     //create 100 random number
    ArrayList<Integer> arraylist= new ArrayList<Integer>();
    Random rand= new Random();
     int total_50=0;
     for ( int i = 0; i < 100; i++) {
       int num=rand.nextInt(100);
      arraylist.add(Integer.valueOf(num));
       //get number of >50
       if(num>50)total_50++;
    }
    System.out.println( "numbers of >50 is: "+total_50);
    
     //sort the arraylist
    Comparator<Integer> comp= new MyComparator();
    Collections.sort(arraylist, comp);
     //out min & max
    System.out.println( "Min number is: "+arraylist.get(0));
    System.out.println( "Max number is: "+arraylist.get(99));
    
  }
    
   public static class MyComparator implements Comparator<Integer>{

    @Override
     public int compare( final Integer o1, final Integer o2) {
       final Integer x=(Integer)o1;
       final Integer y=(Integer)o2;
       if (x>y) {
         return 1;
      } else{
         return 0;
      }
    }
    
  }
}