1.random使用

package daigua3;
import java.util.Random;

public class Random1 {
    public static void main(String[] args) {
        Random r = new Random();
        
        // 取0-9之間的隨機數
        for (int i = 0; i < 10; i++) {
            int num = r.nextInt(10);
            System.out.println(num);
        }
        
        // 取1-100之間的隨機數
        int i = r.nextInt(100) + 1;
        System.out.println(i);
    }
}
 

2.陣列

定義及使用

package daigua3;

public class Array1 {
    public static void main(String[] args) {
        // 定義時賦值
        int[] arr = {1,2,3};
        System.out.println(arr);
        System.out.println(arr[0]);
        System.out.println(arr[1]);
        System.out.println(arr[2]);
        
        // 定義再賦值
        int[] arr1 = new int[3];
        arr1[0] = 1;
        arr1[1] = 2;
        arr1[2] = 3;
        for (int i = 0; i < arr1.length; i++) {
            System.out.println(arr1[i]);
        }       
    }
}
 

陣列的記憶體分配