Question

我已经研究了类似的问题，但是没有一个适合这个问题。我正在尝试从名为nextQuestion（）的方法名称访问可绘制数组，但是我不断收到错误消息，无法解析符号'ballArray'，请提供任何帮助。我只是觉得这应该起作用，但不知道为什么。这是我的代码。

公共类MainActivity扩展了AppCompatActivity {

    ImageView mBallDisplay;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        int quote;

        mBallDisplay = (ImageView) findViewById(R.id.image_eightBall);
        Button nextbutton = (Button) findViewById(R.id.nextbutton);
        Button prevbutton = (Button) findViewById(R.id.prevbutton);

         final int[] ballArray = {
                R.drawable.ball1,
                R.drawable.ball2,
                R.drawable.ball3,
                R.drawable.ball4,
                R.drawable.ball5
        };

        //next button
        nextbutton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                nextQuestion();

            }
        });



        //previous button
        prevbutton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {


                prevQuestion();
            }
        });

    }

    private void nextQuestion(){
        mBallDisplay.setImageResource(ballArray[4]);
    }

    private void prevQuestion(){

    }

}

Answer 1

您无法从ballArray访问nextQuestion()的原因是因为它是在单独的方法中声明的。如果希望从nextQuestion()内部访问它，则需要在该级别使其可见：

ImageView mBallDisplay;

final int[] ballArray = {
  R.drawable.ball1,
  R.drawable.ball2,
  R.drawable.ball3,
  R.drawable.ball4,
  R.drawable.ball5
};

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    int quote;

    mBallDisplay = (ImageView) findViewById(R.id.image_eightBall);
    Button nextbutton = (Button) findViewById(R.id.nextbutton);
    Button prevbutton = (Button) findViewById(R.id.prevbutton);

    //next button
    nextbutton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            nextQuestion();

        }
    });



    //previous button
    prevbutton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {


            prevQuestion();
        }
    });

}

private void nextQuestion(){
    mBallDisplay.setImageResource(ballArray[4]);
}

private void prevQuestion(){

}

}

Answer 2

这样做：-

public class MainActivity extends AppCompatActivity {

    ImageView mBallDisplay;

    int[] ballArray = {
                R.drawable.ball1,
                R.drawable.ball2,
                R.drawable.ball3,
                R.drawable.ball4,
                R.drawable.ball5
        };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        int quote;

        mBallDisplay = (ImageView) findViewById(R.id.image_eightBall);
        Button nextbutton = (Button) findViewById(R.id.nextbutton);
        Button prevbutton = (Button) findViewById(R.id.prevbutton);

        //next button
        nextbutton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                nextQuestion();

            }
        });

        //previous button
        prevbutton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {


                prevQuestion();
            }
        });

    }

    private void nextQuestion(){
        mBallDisplay.setImageResource(ballArray[4]);
    }

    private void prevQuestion(){

    }

}

如何从方法访问可绘制数组

2 个答案: