java列表问题<&燃气轮机；

我对java列表和arrayList不太熟悉。。我只需要一些工作顺利的附加和排序

我的算法很简单：

set a father string 
add father to speciesList
    mutate father to some new child
    make this new child the future father
    go to step 2

这里给出了

ga_

和

ga_结构

的定义

public class ga_struct {

    public String gene;
    public int fitness;

}


public class ga_{

    public List<ga_struct> vector= new ArrayList<ga_struct>();

        public void sortspecies()
        {
        Collections.sort(vector,new Comparator<ga_struct>() {
        @Override
        public int compare(ga_struct o1, ga_struct o2) {
            int res;
            if(o1.fitness<o2.fitness)
                res=-1;
            else if(o1.fitness>o2.fitness)
                res=1;
            else 
                res=0;
            return res;
                 }
              }
                  );

     }


    public ga_struct mutate(ga_struct parent)
    {
        Random r= new Random();
        ......     do some modification to the parent
        return parent;
    }
}

---

第一个循环证明了突变进展缓慢。。我也在突变后立即添加了，那为什么后来所有的都被最新版本覆盖了呢？

你到处都在使用一个对象，你永远不会在列表中添加一个新的

ga_struct

实例。您的

mutate（）

方法似乎只是修改

父参数并返回它-它仍然是同一个对象，只是被修改了，这意味着它到处都被修改了

public ga_struct mutate(ga_struct parent)
{
    Random r= new Random();
    ......     do some modification to the parent
    return parent;
}

您确实创建了一个新的
ga_struct
实例，但通过将引用设置为变异的
父对象来立即覆盖它（该实例仍然是相同的，刚刚修改）：

您没有创建新对象，而是将父对象添加到向量中9次

基本上你得到的是

父亲->obj@123

列表对象的外观是
[ obj@123, obj@123, obj@123，…]

您将需要创建新实例来记录这一点。我建议实现“clone（）”方法来实现这一点。
首先，您的对象使用有点奇怪

在《变异》中，你似乎正在改变并回归父亲

这意味着您的列表将包含对同一实例的多个引用

澄清：

public ga_struct mutate(ga_struct parent) //takes in reference to parent
{
    Random r= new Random(); //modifies parent
    ......     do some modification to the parent
    return parent; //return reference to parent
}

主要是：

    ga_ newSpecies = new ga_();
    Random r= new Random(10);
    ga_struct father= new ga_struct();//instantiate father
    father.gene="123";
    newSpecies.vector.add(father);

    for (int i = 1; i < 10; i++) {
        ga_struct ng = new ga_struct();//create new instance for child
        ng=newSpecies.mutate(father);//set ng as reference to same instance as father, instance instantiated on previous line is discarded
        ng.fitness=i;
        newSpecies.vector.add(ng);
        father=ng;          
        System.out.println(newSpecies.vector.get(i).gene+" with fitness factor "+newSpecies.vector.get(i).fitness);

    }

a_ newSpecies = new ga_();
    Random r= new Random(10);
    ga_struct father= new ga_struct();
    father.gene="123";
    newSpecies.vector.add(father);

    for (int i = 1; i < 10; i++) {    
        ga_struct ng=newSpecies.mutate(father);
        ng.fitness=i;
        newSpecies.vector.add(ng);
        father=ng;          
        System.out.println(newSpecies.vector.get(i).gene+" with fitness factor "+newSpecies.vector.get(i).fitness);

    }

    newSpecies.sortspecies();
    System.out.println("\ncurrent population\n");

    for (int i = 0; i < 10; i++) {
        System.out.println(newSpecies.vector.get(i).gene+" with fitness factor "+newSpecies.vector.get(i).fitness);
    }

主要是：

    ga_ newSpecies = new ga_();
    Random r= new Random(10);
    ga_struct father= new ga_struct();//instantiate father
    father.gene="123";
    newSpecies.vector.add(father);

    for (int i = 1; i < 10; i++) {
        ga_struct ng = new ga_struct();//create new instance for child
        ng=newSpecies.mutate(father);//set ng as reference to same instance as father, instance instantiated on previous line is discarded
        ng.fitness=i;
        newSpecies.vector.add(ng);
        father=ng;          
        System.out.println(newSpecies.vector.get(i).gene+" with fitness factor "+newSpecies.vector.get(i).fitness);

    }

a_ newSpecies = new ga_();
    Random r= new Random(10);
    ga_struct father= new ga_struct();
    father.gene="123";
    newSpecies.vector.add(father);

    for (int i = 1; i < 10; i++) {    
        ga_struct ng=newSpecies.mutate(father);
        ng.fitness=i;
        newSpecies.vector.add(ng);
        father=ng;          
        System.out.println(newSpecies.vector.get(i).gene+" with fitness factor "+newSpecies.vector.get(i).fitness);

    }

    newSpecies.sortspecies();
    System.out.println("\ncurrent population\n");

    for (int i = 0; i < 10; i++) {
        System.out.println(newSpecies.vector.get(i).gene+" with fitness factor "+newSpecies.vector.get(i).fitness);
    }

a_uu9;newSpecies=new ga_u9;（）；
随机r=新随机（10）；
ga_结构父对象=新ga_结构（）；
父亲。基因=“123”；
newSpecies.vector.add（父）；
对于（inti=1；i<10；i++）{
ga_struct ng=新物种变异（父亲）；
ng.适合度=i；
新物种.载体.添加（ng）；
父亲=ng；
System.out.println（newSpecies.vector.get（i）.gene+“带适应度因子”+newSpecies.vector.get（i）.fitness）；
}
新物种。sortspecies（）；
System.out.println（“\n当前人口\n”）；
对于（int i=0；i<10；i++）{
System.out.println（newSpecies.vector.get（i）.gene+“带适应度因子”+newSpecies.vector.get（i）.fitness）；
}
如果我理解正确，两组println之间发生的唯一事情就是调用
sortSpecies（）
。所以，也许你应该让我们看看这个方法在做什么。从技术上来说，他是这样做的，但是他马上就放弃了。但这是正确的想法。他在代码中至少两个地方创建了新的
ga_struct
。@Joachim Sauer你说得对，我应该重新表述一下-我的意思是，他似乎到处都在使用同一个实例（他覆盖了@DHall指出的新对象）-因此，在每次迭代中修改它会导致
列表中有10个条目，所有条目都是相同的对象。非常感谢。。我为自己是一个如此糟糕的程序员而道歉！。。不管怎样，下面解决了我的问题-parent.gene=origin.gene；而不是父=源；为什么？actuallyparent=原点意味着父对象和原点将指向同一个对象。parent.gene=origin.gene将更改原始基因的值。如果您仔细阅读其中一些内容，可能会有所帮助：
    ga_ newSpecies = new ga_();
    Random r= new Random(10);
    ga_struct father= new ga_struct();//instantiate father
    father.gene="123";
    newSpecies.vector.add(father);

    for (int i = 1; i < 10; i++) {
        ga_struct ng = new ga_struct();//create new instance for child
        ng=newSpecies.mutate(father);//set ng as reference to same instance as father, instance instantiated on previous line is discarded
        ng.fitness=i;
        newSpecies.vector.add(ng);
        father=ng;          
        System.out.println(newSpecies.vector.get(i).gene+" with fitness factor "+newSpecies.vector.get(i).fitness);

    }

    public ga_struct mutate(ga_struct parent)
{
    ga_struct ng = new ga_struct();
    ng.gene = father.gene;
    Random r= new Random();
    //do some modification to ng
    return ng;
}

a_ newSpecies = new ga_();
    Random r= new Random(10);
    ga_struct father= new ga_struct();
    father.gene="123";
    newSpecies.vector.add(father);

    for (int i = 1; i < 10; i++) {    
        ga_struct ng=newSpecies.mutate(father);
        ng.fitness=i;
        newSpecies.vector.add(ng);
        father=ng;          
        System.out.println(newSpecies.vector.get(i).gene+" with fitness factor "+newSpecies.vector.get(i).fitness);

    }

    newSpecies.sortspecies();
    System.out.println("\ncurrent population\n");

    for (int i = 0; i < 10; i++) {
        System.out.println(newSpecies.vector.get(i).gene+" with fitness factor "+newSpecies.vector.get(i).fitness);
    }