public class lianxi { public static void main(String[] args){ double d=1.23; Dec dec=new Dec(); dec.decrement(d); System.out.println(d); } class Dec{ public Dec(){}; public double decrement(double d){ return d=d-1; }
}} 发错了,汗!
public class lianxi { public static void main(String[] args){ double d=1.23; Dec dec=new Dec(); dec.decrement(d); System.out.println(d); } class Dec{ public Dec(){}; public double decrement(double d){ return d=d-1; }
public class lianxi { public static void main(String[] args){ double d=1.23; lianxi b1 = new lianxi(); Dec dec= b1.new Dec(); dec.decrement(d); System.out.println(d); } class Dec{ public Dec(){}; public double decrement(double d){ return d=d-1; } } 就没了,输出: 1.23 }
public class lianxi { public static void main(String[] args){ double d=1.23; lianxi b1 = new lianxi(); Dec dec= b1.new Dec(); dec.decrement(d); System.out.println(d); } class Dec{ public Dec(){}; public double decrement(double d){ return d=d-1; } }}
public class lianxi { public static void main(String[] args) { double d = 1.23; lianxi l = new lianxi();//先实例一个lianxi对象 Dec dec = l.new Dec(); dec.decrement(d); System.out.println(d); } class Dec { public Dec() { } public double decrement(double d) { return d = d - 1; } }}
public class lianxi { public static void main(String[] args){ double d=1.23; lianxi b1 = new lianxi(); Dec dec= b1.new Dec(); dec.decrement(d); System.out.println(d); } class Dec{ public Dec(){}; public double decrement(double d){ return d=d-1; } }}
把你的 Dec dec=new Dec(); 变成 lianxi lx = new lianxi(); Dec dec=lx.new Dec(); 就可以了。。
public class lianxi { public static void main(String[] args){ double d=1.23; double re;//勇于接收dec.decrement(d)的返回值 lianxi lx=new lianxi(); Dec dec=lx.new Dec(); re=dec.decrement(d); System.out.println(re); } class Dec{ public Dec(){}; public double decrement(double d){ return d=d-1; } } } 解释两个问题: 1.要创建内部类的实力,必须先实例化外部类; 2.Java的参数传递为值传递,必须定义另一个变量来接收方法的返回值
public class lianxi {
public static void main(String[] args){
double d=1.23;
Dec dec=new Dec();
dec.decrement(d);
System.out.println(d);
}
class Dec{
public Dec(){};
public double decrement(double d){
return d=d-1;
}
}}
发错了,汗!
public class lianxi {
public static void main(String[] args){
double d=1.23;
Dec dec=new Dec();
dec.decrement(d);
System.out.println(d);
}
class Dec{
public Dec(){};
public double decrement(double d){
return d=d-1;
}
}}
lianxi.Dec dec=t.new Dec();
内部类创建错了~
public static void main(String[] args){
double d=1.23;
lianxi b1 = new lianxi();
Dec dec= b1.new Dec();
dec.decrement(d);
System.out.println(d);
}
class Dec{
public Dec(){};
public double decrement(double d){
return d=d-1;
}
}
就没了,输出:
1.23 }
public static void main(String[] args){
double d=1.23;
lianxi b1 = new lianxi();
Dec dec= b1.new Dec();
dec.decrement(d);
System.out.println(d);
}
class Dec{
public Dec(){};
public double decrement(double d){
return d=d-1;
}
}}
public class lianxi {
public static void main(String[] args) {
double d = 1.23;
lianxi l = new lianxi();//先实例一个lianxi对象
Dec dec = l.new Dec();
dec.decrement(d);
System.out.println(d);
} class Dec {
public Dec() {
} public double decrement(double d) {
return d = d - 1;
} }}
public static void main(String[] args){
double d=1.23;
lianxi b1 = new lianxi();
Dec dec= b1.new Dec();
dec.decrement(d);
System.out.println(d);
}
class Dec{
public Dec(){};
public double decrement(double d){
return d=d-1;
}
}}
Dec dec=new Dec();
变成
lianxi lx = new lianxi();
Dec dec=lx.new Dec();
就可以了。。
public static void main(String[] args){
double d=1.23;
double re;//勇于接收dec.decrement(d)的返回值
lianxi lx=new lianxi();
Dec dec=lx.new Dec();
re=dec.decrement(d);
System.out.println(re);
}
class Dec{
public Dec(){};
public double decrement(double d){
return d=d-1;
}
}
}
解释两个问题:
1.要创建内部类的实力,必须先实例化外部类;
2.Java的参数传递为值传递,必须定义另一个变量来接收方法的返回值