Java
자바의신 ch24
langsamUndStetig
2022. 7. 6. 17:20
package d.collection.practice;
import java.util.Random;
import java.util.Hashtable;
import java.util.Set;
public class RandomNumberStatics {
private final int DATA_BOUNDARY = 50;
Hashtable<Integer, Integer> hashtable = new Hashtable<>();
public static void main(String[] args) {
RandomNumberStatics sample = new RandomNumberStatics();
sample.getRandomNumberStatistics();
}
public void getRandomNumberStatistics() {
Random random = new Random();
for(int i=0;i<5000;i++) {
int tempNumber = random.nextInt(DATA_BOUNDARY)+1;
putCurrentNumber(tempNumber);
}
printStatistics();
}
public void putCurrentNumber(int tempNumber){
//contains를 사용했을 떈 NullPointerException이 발생했다.
if (hashtable.containsKey(tempNumber)==true) {
hashtable.put(tempNumber, hashtable.get(tempNumber)+1);
} else {
hashtable.put(tempNumber, 1);
}
}
public void printStatistics() {
Set<Integer> keys = hashtable.keySet();
for(Integer key : keys) {
System.out.print(key+"="+hashtable.get(key)+ " ");
if(key%10-1==0) System.out.println();
}
}
}
