如何访问在另一个Java类的方法中声明的变量？

Question

I have recently started trying my hands at Java and I am stuck at this problem. I have two Java files called Main_file.java and Helper.java. The Helper.java file contains a String variable called the name, which I wish to access form my Mainfile.java and assign to a string variable x. The files look soemthing like this.

Main.java

public class Mainfile{

    Helper myhelper =new MyHelper();

    public void create_func(){
        String x =  /* assign the value name from the helper file */;
    }

Helper.java

public class Helper{

    public void add_name() {
        String name = "New_name";
    }
}

But this does not seem to work. I am not really sure if the method I am trying is right or wrong. Could somebody please help me? Thank you in advance.

Answer 1

You can not directly access a local variable of a method of another class. You can do it by making the method returning the object and access it by calling the method by an object of the class. This is how you can:

public class Mainfile{
Helper myhelper =new Helper();

public void create_func(){

    String x =  myhelper.add_name();
} 
}

public class Helper{

  public String add_name(){
      String name = "New_name";
      return name;
}
}

Answer 2

The variable name you create in your Helper class is not class-member but only a member which exists in the method add_name()

If you want a class member you'll have to create it like this:

public class Helper{
    String name = "New_name";
}

then you can access it like this:

public class MainFile{

    Helper myHelper = new Helper();

    public void create_func(){
        String x =  myHelper.name;
    }
}

Many people will say that class-members "have" to be private, so it might be nicer to create getters and setters for the class member:

public class Helper{
    private String name = "New_name";
    public String getName() {
        return name;
    }
    public void setName(String newName) {
        name = newName;
    }
}

public class MainFile{

    Helper myHelper = new Helper();

    public void create_func(){
        String x =  myHelper.getName();
    }
}