java学习笔记(3)
java学习笔记(3)
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之间的随机数
for (int i = 0; i < 10; i++) {
int num = r.nextInt(10);
System.out.println(num);
}
// 取1-100之间的随机数
int i = r.nextInt(100) + 1;
System.out.println(i);
}
}
2.数组
定义及使用
package daigua3;
public class Array1 {
public static void main(String[] args) {
// 定义时赋值
int[] arr = {1,2,3};
System.out.println(arr);
System.out.println(arr[0]);
System.out.println(arr[1]);
System.out.println(arr[2]);
// 定义再赋值
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]);
}
}
}
数组的内存分配