java对象共享类变量

class Lader{
 double above ,height;
 static double bottom;
 void setAbove(double a){
  above=a;
 }
 void setBottom(double b){
  bottom=b;
 }
 double getAbove(){
  return above;
 }
 double getBottom(){
  return bottom;
 }
}
class example4_4 {
 public static void main(String arg[]){
  Lader.bottom=60;
  Lader laderOne,laderTwo;
  System.out.println("现在所有Lader对象的bottom都是"+Lader.bottom);
  laderOne=new Lader();
  laderTwo=new Lader();
  System.out.println("laderOne的bottom:"+laderOne.getBottom());
  System.out.println("laderTwo的bottom:"+laderTwo.getBottom());
  laderOne.setAbove(11);
  laderTwo.setAbove(22);
  laderTwo.setBottom(100);
  System.out.println("现在所有Lader对象的bottom都是"+Lader.bottom);
  System.out.println("laderOne的above:"+laderOne.getAbove());
  System.out.println("laderTwo的above:"+laderTwo.getAbove());
  
  
 }
}