question1:class X2{
public X2 x;
public static void main(String[] args){
X2 x2=new X2();
X2 x3=new X2();
x2.x=x3;
x3.x=x2;
x2=new X2();
x3=x2;
}
}
问:有几个符合垃圾搜集条件?question2:X3 x2=new X3();
X3 x3=new X3();
X3 x5=x3;
x3=x2;
X3 x4=x3;
x2=null;
//insert code问:在//insert code处插入哪两行,可以使一个对象符合垃圾搜集条件?(选2个)
A x3=null;
B x4=null;
C x5=null;
D x3=x4;
E x5=x4;
public X2 x;
public static void main(String[] args){
X2 x2=new X2();
X2 x3=new X2();
x2.x=x3;
x3.x=x2;
x2=new X2();
x3=x2;
}
}
问:有几个符合垃圾搜集条件?question2:X3 x2=new X3();
X3 x3=new X3();
X3 x5=x3;
x3=x2;
X3 x4=x3;
x2=null;
//insert code问:在//insert code处插入哪两行,可以使一个对象符合垃圾搜集条件?(选2个)
A x3=null;
B x4=null;
C x5=null;
D x3=x4;
E x5=x4;
第二题:CE,C x5=null;这个不解释了。解释下E。x5=x4; x4是x3的引用。x3保存的是x2的引用(相对应的代码 x3=x2;
X3 x4=x3;),而X2又被设置为null.所以符合回收条件.小弟愚见.各位大虾指点
question2:AB(这好象答案不唯一)
1.空引用
2.重新为引用变量赋值
3.隔离引用第一个问题是属于隔离引用: X2 x2=new X2();
X2 x3=new X2(); x2.x=x3;
x3.x=x2;
两个对象相互引用
x2=new X2();
x3=x2;
使用新引用断开了x2,x3之前的引用
所以有两个满足