[英]Get instance variable by its name
我有两个班,A和B。
B包含A的实例。我想按其名称从B返回A的实例:
class A
{
public String name;
public A (String name)
{
this.name = name;
}
}
class B
{
public A a1;
public A a2;
public A a3;
public B ()
{
this.a1 = new A ("a1");
this.a2 = new A ("a2");
this.a3 = new A ("a3");
}
public A get_A_byName (String name)
{
// Is it possible to write something like this? B will always contain only instances of A
for (A a : B.variables)
{
if (a.name.equals(name))
{
return a;
}
// Or in case A doesn't have a variable "name", can I get an A instance by its declared name in B?
if (a.getClass().getName().equals(name))
{
return a;
}
}
}
}
是否可以执行代码注释中描述的操作? 提前致谢。
这是为将键(在这种情况下为字符串)与对象配对而创建的哈希图的多少
class B
{
private HashMap<String,A> theAs=new HashMap<String,A>(); //give better name
public B ()
{
theAs.put("a1",new A ("a1")); //A probably doesn't need to keep its own name internally now, but have left it as its in your original code
theAs.put("a2",new A ("a2"));
theAs.put("a3",new A ("a3"));
}
public A get_A_byName (String name)
{
return theAs.get(name);
}
}
在Java 7+中,您不需要添加第二个<String,A>
,菱形推断就可以了,因此在Java 7或更高版本中,它将是:
private HashMap<String,A> theAs=new HashMap<>();
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.