如何从 main 设置 setter 并从另一个获取 getter Class Java 7

Question

我有 3 个 class； 1) Main 2) SettersAndGetters 3) AnotherClass。在我的主 class 中，我设置了设置器。我正在寻找一种从 AnotherClass 访问这些值的方法。现在我得到一个空值，这是由于我创建的新实例。那么我该如何解决这个问题，如何检索我在 main 中设置的值。

public class Main{

   public static void main(String args[]){
      GettersAndSetters sg = new GettersAndSetters();
      AnotherClass copyOfSG = new AnotherClass();

      sg.setName("Mo");
      sg.setAge(20);
      sg.setIdNum("77777");

      System.out.print("Name : " + sg.getName() + " Age : " + sg.getAge()+"\n");
      System.out.println(copyOfSG.printout());
      //In here I am trying to print the value that is 
      //in my 3rd class "AnotherClass" but i am getting null. 

   }
}

输出：

Name : Mo Age : 20
Age: 0
Name: null

SettersAndGetters:

public class GettersAndSetters{
   private String name;
   private String idNum;
   private int age;
   public int getAge(){
      return age;
   }
   public String getName(){
      return name;
   }

   public String getIdNum(){
      return idNum;
   }

   public void setAge( int newAge){

      age = newAge;
   }

   public void setName(String newName){
      name = newName;
   }

   public void setIdNum( String newId){
      idNum = newId;
   }
}

另一个班级：

public class AnotherClass {

    public void printout() {
        GettersAndSetters gs1 = new GettersAndSetters();

        System.out.println("Age: " + gs1.getAge());
        System.out.println("Name: " + gs1.getName());

        System.out.println();

    }

}

Answer 1

In my main class, I set the setters. And I am looking for a way to access these values from AnotherClass

替换

System.out.println(copyOfSG.printout());

和

copyOfSG.printout(sg);

和你的printout()方法

public void printout(GettersAndSetters gs1) {
       //No need of creating GettersAndSetters object

       System.out.println("Age: " + gs1.getAge());
       System.out.println("Name: " + gs1.getName());

}

Answer 2

apache library中有一个classBeanUtil。它会帮助你。此 cass 设置并获取属性值。

BeanUtil.setProperty(<obje_name>, <field_name>, <field-value>);


BeanUtil.getProperty(<object_name>, <field_name>);

Answer 3

发生这种情况是因为您在 Main 和 AnotherClass 中创建了两个独立的 GettersAndSetters 实例。看：

   public static void main(String args[]){

      GettersAndSetters sg = new GettersAndSetters(); //first instance
      AnotherClass copyOfSG = new AnotherClass();

      ...
   }

public class AnotherClass {

    public void printout() {
        GettersAndSetters gs1 = new GettersAndSetters(); //second instance
        ...
    }
}

并且您在 第一个 实例中设置属性，但试图从 第二个 中读取它。要解决这个问题，只需按照 Satya 的建议将 Main 中的第一个实例传递给 AnotherClass 中的方法。

public class AnotherClass {

    public void printout(GettersAndSetters sg) {
        System.out.println("Age: " + sg.getAge());
        System.out.println("Name: " + sg.getName());        
        ...
    }
}

然后用下一种方式称呼它：

public class Main{

   public static void main(String args[]){
      GettersAndSetters sg = new GettersAndSetters();
      AnotherClass copyOfSG = new AnotherClass();

      ...

      copyOfSG.printout(sg);
   }
}

如何从 main 设置 setter 并从另一个获取 getter Class Java 7

How to set Setters from main and get the Getters from Another Class Java 7

java

getter-setter