Getter和setter变量不起作用

Question

我更像是iOS开发人员，所以传递java变量似乎是一个挑战。我抬头看过价值和参考，没有一个对我有用。我似乎无法理解为什么。由于我的应用程序解释起来有点复杂，我将其分解为更简单，实际的问题。我的应用程序有一个android微调器，有三个类别。我想要发生的是根据用户选择的内容简单地更改textview上的文本。在我的碎片视图中，我从基础知识开始，通过调用xml文件中的按钮和textview。

public class AskQuestions extends Fragment {

private Button selectAnswer; 
private TextView displayAnswer;
private Spinner spinner;
public String result;

public String getResult() {
    return result;
}
public void setResult(String result) {
    this.result = result;
}

    public void onCreate(Bundle savedInstabceState){
        super.onCreate(savedInstabceState);

    }
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {

        //Fetching layout
        View rootView = inflater.inflate(R.layout.fragment_questions, container, false);

        selectAnswer  = (Button) rootView.findViewById(R.id.button1);

        displayAnswer = (TextView) rootView.findViewById(R.id.textView1);

        spinner = (Spinner) rootView.findViewById(R.id.planets_spinner);




        //Setting spinner to custom class I created
        spinner.setOnItemSelectedListener(new CustomOnItemSelectedListener());



        //Button clicks when the user selects an item of the spinner, and changes the text
        //based on what item is selected.
        selectAnswer.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub

                        //This is where I am confused.
                        result = getResult();

                        displayAnswer.setText(result);              

            }
        });


        return rootView;
    }



}

行。这主要是我的麻烦所在。如何根据用户从此课程中选择的内容更改文本视图？

public class CustomOnItemSelectedListener implements OnItemSelectedListener {

    //Calling object in to display in the view

    AskQuestions question = new AskQuestions();

    //When a user selects an item off of the spinner, the position changes 
    //accordingly (spinner works just fine, changing the text on the textview from this class
    //seems to be most of my trouble.
    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int pos,
        long id) {

    switch (pos) {
    case 0:     
        //This does not work when a user selects an item, and clicks a button to review the result
        question.setResult("You selected index zero");
        break;
    case 1:
        //Does not work
        question.setResult("You selected index one");
        break; 
    case 2: 
        //Does not work
        question.setResult("You selected index 2");
        break;
    }
    }

    @Override
    public void onNothingSelected(AdapterView<?> arg0) {
    // TODO Auto-generated method stub
    }
}

Answer 1

我不是Android开发人员，但您正在这样做：

AskQuestions question = new AskQuestions();

创建用户界面中不存在的新AskQuestions对象，因此您正在更改未显示的对象。

您需要从AskQuestions引用接口的CustomOnItemSelectedListener对象才能修改该UI对象。 @DerGolem的答案向您展示了一种方法; - ）

此致

Answer 2

最简单的选择是将监听器变为匿名类：

public class AskQuestions extends Fragment {

    private Button selectAnswer; 
    private TextView displayAnswer;
    private Spinner spinner;
    public String result;

    public String getResult() {
        return result;
    }
    public void setResult(String result) {
        this.result = result;
    }

    public void onCreate(Bundle savedInstabceState){
        super.onCreate(savedInstabceState);

    }
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {

        //Fetching layout
        View rootView = inflater.inflate(R.layout.fragment_questions, container, false);

        selectAnswer  = (Button) rootView.findViewById(R.id.button1);

        displayAnswer = (TextView) rootView.findViewById(R.id.textView1);

        spinner = (Spinner) rootView.findViewById(R.id.planets_spinner);




        //Setting spinner to custom class I created
        spinner.setOnItemSelectedListener(new OnItemSelectedListener (){
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int pos,
             long id) {
                switch (pos) {
                case 0:     
                    displayAnswer.setText("You selected index 0");
                    break;
                case 1:
                    displayAnswer.setText("You selected index one");
                    break; 
                case 2: 
                    displayAnswer.setText("You selected index 2");
                    break;
                }
            }

            @Override
            public void onNothingSelected(AdapterView<?> arg0) {
            // TODO Auto-generated method stub
            }
        });



        //Button clicks when the user selects an item of the spinner, and changes the text
        //based on what item is selected.
        selectAnswer.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub

                        //This is where I am confused.
                        result = getResult();

                        displayAnswer.setText(result);              

            }
        });


        return rootView;
    }



}