//私有变量 public Class A { B b=new B(); b.setStr1("ok"); }public Class B { private String str1=""; public void setStr1(String str2) { str1=str2; } }//公共变量 public Class A { B b=new B(); b.str1="ok"; } public Class B { public String str1=""; }//静态公共变量 public Class A { B.str1="ok"; } public Class B { public static String str1=""; }
最主要的是“另一个变量” 看个例子 class Lader { double above,bottom,height; Lader(double a,double b,double h) { above=a; bottom=b; height=h; } public void setAbove(double a) { above=a; } public void setBottom(double b) { bottom=b; } public void setHeight(double h) { height=h; } double computeArea() { return (above+bottom)*height/2.0; } } public class Example { public static void main(String args[]) { double area1,area2=0; Lader laderOne,laderTwo; laderOne=new Lader(5,10,12); laderTwo=new Lader(10,20.45,20); area1=laderOne.computeArea(); area2=laderTwo.computeArea(); System.out.printf("laderOne和laderTwo的面积分别是:%n%f,%f\n",area1,area2); laderOne.setAbove(10); laderTwo.setBottom(40); area1=laderOne.computeArea(); area2=laderTwo.computeArea(); System.out.printf("laderOne和laderTwo的面积分别是:%n%f,%f\n",area1,area2); } }
public Class A
{
B b=new B();
b.setStr1("ok");
}public Class B
{
private String str1="";
public void setStr1(String str2)
{
str1=str2;
}
}//公共变量
public Class A
{
B b=new B();
b.str1="ok";
}
public Class B
{
public String str1="";
}//静态公共变量
public Class A
{
B.str1="ok";
}
public Class B
{
public static String str1="";
}
看个例子
class Lader
{
double above,bottom,height;
Lader(double a,double b,double h)
{
above=a;
bottom=b;
height=h;
}
public void setAbove(double a)
{
above=a;
}
public void setBottom(double b)
{
bottom=b;
}
public void setHeight(double h)
{
height=h;
}
double computeArea()
{
return (above+bottom)*height/2.0;
}
}
public class Example
{
public static void main(String args[])
{
double area1,area2=0;
Lader laderOne,laderTwo;
laderOne=new Lader(5,10,12);
laderTwo=new Lader(10,20.45,20);
area1=laderOne.computeArea();
area2=laderTwo.computeArea();
System.out.printf("laderOne和laderTwo的面积分别是:%n%f,%f\n",area1,area2);
laderOne.setAbove(10);
laderTwo.setBottom(40);
area1=laderOne.computeArea();
area2=laderTwo.computeArea();
System.out.printf("laderOne和laderTwo的面积分别是:%n%f,%f\n",area1,area2);
}
}
public谁都能用
protected他的继承类才能用
private他自己才能用
如果什么都不指定,就是和他在同一层包里的累才能用不知说得清楚不