如何获取方法的返回值？

Question

I'm a newbie creating a unit converter. I have two classes, I have this method in the first class:

public String cardName;

public String StartConversion(View view){
    Intent intent = new Intent(this, ConversionActivity.class);
    startActivity(intent);
    return cardName = view.getResources().getResourceEntryName(view.getId());
}

I would like to get and use the cardName's value in my second class, so:

MainActivity myObj = new MainActivity();
Toast.makeText(getApplicationContext(), "cardName: " + myObj.cardName, Toast.LENGTH_LONG).show();

But this doesn't work. I know local variables are only accessible inside their scope so I did this instead. They say you can only access it if you make it a class member, that does work but then it has a NULL value.

Answer 1

Typically, you'd a) create some class, b) make class members "private", then c) expose those members with getter and setter methods .

EXAMPLE:

public class MyClass {

  private String cardName;

  public void StartConversion(View view){
    Intent intent = new Intent(this, ConversionActivity.class);
    startActivity(intent);
    cardName = view.getResources().getResourceEntryName(view.getId());
  }

  public getCardName() { return cardName; }
}

Then whatever class wanted to access "cardName" would call:

String cardName = myObject.getCardName();

Look here for more details: Java Getter and Setter Tutorial, Nam Ha Minh

Answer 2

There exists a train of way to resolve your problem. For instance,

First- the method of StartConversion works to set the card name and then provide a method of getter to access.

Second- Only use the method of StartConversion to return that you want. But you ought to change the code to return view.getResources().getResourceEntryName(view.getId()); , to remove the cardName = . The outer class should be called the method to access that you want.

In a word, either call the method to access directly or giving a setter then using the getter to access.