test.java

对于初学者

public class test
{
   public static void main(String []args)
      {
          System.out.println("Hello");
          System.out.println("www.xiaonei.com");
          System.out.println('a'+1);//输出98
          System.out.println(""+'a'+1);//输出a1
          drawRectangle(-2,3);
          drawRectangle(3,5);
          drawRectangle(6,8);
          calcurate(2,3);
          calcurate(-3,5);
          int area =getArea(3,5);
          System.out.println("3*5="+area);
          System.out.println("2*4="+getArea(2,4));
      }
/**
*@param x 行
*@param y 列
*/
   static void drawRectangle(int x,int y)//必须要加static，否则无法从静态上下文中引用非静态
    {
       if(x<=0 || y<=0)
         return;
       for(int i=0;i<x;i++)
        { 
             for(int j=0;j<y;j++)
              { 
                System.out.print('*'); //注意不是println打印一个就换行(print不会换行)
              }
          System.out.println();
        }
       
    }
   static void calcurate(int x,int y)//必须要加static，否则无法从静态上下文中引用非静态
   {
       if(x<=0 || y<=0)
         return;
      int sum =x*y; 
      System.out.println(sum); 
      
   } 
  static int getArea(int x,int y)
   {
      int sum =x*y;
      return sum;//或者return x*y;
   }
}