数据类型

public class Demo02 {
     public static void main(String[] args) {
         String a = "hello";
         int num = 10;
         byte num2 = 20;
         short num3 = 30;
         long num4 = 30L;//long类型要在数字后加个L
         System.out.println(num4);
         //小数：浮点数
         float num5 =50.1F;
         double num6 =3.141892653589793238462643;
         //字符
         char name ='国';
         //字符串，string不是关键字，类
         //String namea ="夕阳";
         //布尔值：是非
         boolean flag =true;
         //boolean flag =false;

     }
}