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;
/**
*
*/
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));
}
}
package math;
import java.util.Comparator;
/**
*
*/
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;
/**
*
*/
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;
}
}
}
}
责任编辑：小草
