java - 如何将对象从一个类传输到另一个类 - JAVA

Question

我正在尝试在饼图中显示百分比值，因为我在Personality类中有百分比值，而Chart类是我需要的地方来展示它。我的代码结构如下:

个性.JAVA

   Tree C = gson.fromJson(profile.toString(), Tree.class);  

                Tree.SubTree t = C.getTree(); 
                ArrayList<Children> mc = t.getChildren();
                Children c1 = mc.get(0);

                ArrayList<Children1> c2 = c1.getChildren();
                Children1 obj1 = c2.get(0);

                private Children1 obj1; //ERROR-ILEGAL START OF EXPRESSION 


                public Children1 getObj1(){
                return this.obj1;
               } 

         /**       ArrayList<child2> c3 = obj1.children;
                child2 obj2 = c3.get(0);

                ArrayList<child3> c4 = obj2.children;
                child3 obj3 = c4.get(0);  **/


                System.out.println(obj1.getPercentage()); //ERROR - IDENTIFIER EXPECTED

Children1.JAVA

   public class Children1 {
     private String category;
     private String id;
     private String name;
     private double percentage;
     private double sampling_error;
     private ArrayList<Children2> children;

    public Double getPercentage() {
     return percentage;
   }
/**
* 
* @param percentage
* The percentage
*/
    public void setPercentage(Double percentage) {
    this.percentage = percentage;
    }
}

Tree.JAVA(不确定这个类是否必要，但它就是)

public class Tree {
    private SubTree tree;  
    @Override
    public String toString() {
        return "ID: " + id + "\n" + "Name: "+ "\n" + tree+ "\n" ;
    }  
    class SubTree{
    private String id;
    private String name;
    private ArrayList<Children> children; //Gets Arraylist from Class - Children


    public ArrayList<Children> getChildren() {
    return children;
    }

    public void setChildren(ArrayList<Children> children) {
    this.children = children;
    }     
    }

   public SubTree getTree() {
     return tree;
   }

    public void setTree() {
    this.tree = tree;
    }

}

图表类

private PieDataset createDataset(){
   Personality m = new Personality();
  // Personality.class = Personality();
    DefaultPieDataset result = new DefaultPieDataset();
    result.setValue("Value1",m.obj1 ); //attempted to get obj1 from Persoanlity Class
    result.setValue("Linux", 10);
    result.setValue("Mac", 25);
    return result;
}

所以整个程序是 - 将普通段落转换为 json，然后在使用 java 值生成图形后解析为 java。因此，在本例中，获取百分比值 obj1 以在 Chart 类 中显示。

希望你们理解这个问题并感谢您抽出时间:)

Answer 1

您必须使 Children1 对象在 Personality 类中可见。目前看来 obj1 只是一个局部变量，其作用域仅对该局部方法可见

如果在 Personality 中，您有一个字段 Children1 obj1，则可以通过本地方法或构造函数来设置它。如果 Children1 obj1 的范围是公共(public)的，或者最好它有一个 getter 方法，那么您可以从 Chart 类 中读取它，假设 Children1 obj1 > 在构造函数中创建，即 Personality m = new Personality();

假设您的 Personality 类类似于

public Personailty {
   ....
}

然后你将添加，使其看起来像

public Personailty {
   ....
   private Children1 obj1;

   public Children1 getObj1(){
      return this.obj1;
  } 
}