Java How to access methods from another class

Question

I tried to simplify my predicament as much as possible  I have three classes   Alpha   public class Alpha        public void DoSomethingAlpha               cbeta DoSomethingBeta                   Beta   public class Beta        public void DoSomethingBeta                  Something              Main   public class MainApp        public static void main String   args                         Alpha cAlpha   new Alpha                 Beta cBeta   new Beta               I hope I did not over simplify it   My question is how do I access cBeta DoSomethingBeta   from a method in Alpha

User · Answer

You either need to create an object of type Beta in the Alpha class or its method

Like you do here in the Main Beta cBeta = new Beta();

If you want to use the variable you create in your Main then you have to parse it to cAlpha as a parameter by making the Alpha constructor look like

public class Alpha 
{

    Beta localInstance;

    public Alpha(Beta _beta)
    {
        localInstance = _beta;
    }


     public void DoSomethingAlpha() 
     {
          localInstance.DoSomethingAlpha();     
     }
}

User · Answer

Maybe you need some dependency injection  public class Alpha        private Beta cbeta       public Alpha Beta beta            this cbeta   beta             public void DoSomethingAlpha             this cbeta DoSomethingBeta              and then  Alpha cAlpha   new Alpha new Beta

User · Answer

You need to somehow give class Alpha a reference to cBeta  There are three ways of doing this   1  Give Alphas a Beta in the constructor  In class Alpha write   public class Alpha      private Beta beta     public Alpha Beta beta         this beta   beta          and call cAlpha   new Alpha cBeta  from main    2  give Alphas a mutator that gives them a beta  In class Alpha write   public class Alpha      private Beta beta     public void setBeta  Beta newBeta         this beta   beta         and call cAlpha   new Alpha    cAlpha setBeta beta   from main    or  3  have a beta as an argument to doSomethingAlpha  in class Alpha write   public void DoSomethingAlpha Beta cBeta          cbeta DoSomethingBeta       Which strategy you use depends on a few things  If you want every single Alpha to have a Beta  use number 1  If you want only some Alphas to have a Beta  but you want them to hold onto their Betas indefinitely  use number 2  If you want Alphas to deal with Betas only while you re calling doSomethingAlpha  use number 3  Variable scope is complicated at first  but it gets easier when you get the hang of it  Let me know if you have any more questions

User · Answer

public class WeatherResponse    private int cod  private String base  private Weather main   public int getCod        return this cod     public void setCod int cod       this cod   cod     public String getBase        return base     public void setBase String base       this base   base     public Weather getWeather         return main        default constructor  getters and setters     another class  public class Weather    private int id  private String main  private String description   public String getMain        return main     public void setMain String main       this main   main     public String getDescription        return description     public void setDescription String description       this description   description        default constructor  getters and setters        accessing methods     success       Log i  App   weatherResponse getBase         Log i  App   weatherResponse getWeather   getMain         Log i  App   weatherResponse getWeather   getDescription

User · Answer

Method 1   If the method DoSomethingBeta was static you need only call   Beta DoSomethingBeta      Method 2   If Alpha extends from Beta you could call DoSomethingBeta   directly   public class Alpha extends Beta       public void DoSomethingAlpha               DoSomethingBeta                    Method 3   Alternatively you need to have access to an instance of Beta to call the methods from it   public class Alpha        public void DoSomethingAlpha               Beta cbeta   new Beta              cbeta DoSomethingBeta                    Incidentally is this homework

User · Answer

I have another solution  If Alpha and Beta are your only extra class then why not make a static variable with the image of the class   Like in Alpha class     public class Alpha          public static Alpha alpha          public Alpha                    this alpha   this      Now you you can call the function in Beta class by just using these lines     new Alpha    Alpha alpha DoSomethingAlpha

[java] Java: How to access methods from another class

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