import java.util.Date;
import java.util.Random;
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello world."); // Hello world.
System.out.println(new Date()); // Thu Jan 08 11:30:35 CST 2015
Random rand = new Random(47);
System.out.println(rand.nextInt(256)); // 186
System.out.println(rand.nextInt(256)); // 102
Integer n1 = new Integer(22);
Integer n2 = new Integer(22);
// 对象比较用equals, 基本类型比较用==,
// 自定义类除非override equals(),否则不会得到预期结果.
System.out.println(n1.equals(n2)); // true
System.out.println("round 0.9 = " + Math.round(0.9f)); // round 0.9 = 1
System.out.println("(int) 0.9 = " + (int)(0.9f)); // (int) 0.9 = 0
System.out.println("round 1.9 = " + Math.round(1.9f)); // round 1.9 = 2
System.out.println("(int) 1.9 = " + (int)(1.9f)); // (int) 1.9 = 1
}
}
Java是怎么实现“所有数据类型在所有机器中的大小都是相同的”? Java不需要sizeof().