java - 错误 : cannot find symbol method setAlpha(float). setAlpha() 不适用于具有偏移量的数组

Question

我想根据点击事件在 4 个按钮上应用 setAlpha() 函数。下面是我的代码。我准备了一个 4 个数组，其中包含所有 ID。但是 setAlpha() 会抛出错误。有什么建议吗？

错误:找不到符号方法setAlpha(float)

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private Button yellowBtn;
    private Button greenBtn;
    private Button redBtn;
    private Button blueBtn;
    private Button startBtn;
    String[] tileColor = new String[4];


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

        yellowBtn = findViewById(R.id.yellowBtn);
        greenBtn = findViewById(R.id.greenBtn);
        blueBtn = findViewById(R.id.blueBtn);
        redBtn = findViewById(R.id.redBtn);
        startBtn = findViewById(R.id.startBtn);

        tileColor[0] = "yellowBtn";
        tileColor[1] = "greenBtn";
        tileColor[2] = "blueBtn";
        tileColor[3] = "redBtn";


        startBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startBtn.setEnabled(false);
                randomTile();
            }
        });
        yellowBtn.setOnClickListener(this);
        greenBtn.setOnClickListener(this);
        blueBtn.setOnClickListener(this);
        redBtn.setOnClickListener(this);
    }

    public void randomTile(){
        final int random = new Random().nextInt(4);
        AlphaAnimation animationG = new AlphaAnimation(0.2f, 1.0f);
        animationG.setDuration(500);
        tileColor[random].setAlpha(1f);
        tileColor[random].startAnimation(animationG);
    }

    @Override
    public void onClick(View v) {
        switch(v.getId()){
            case R.id.yellowBtn:
                AlphaAnimation animation1 = new AlphaAnimation(0.2f, 1.0f);
                animation1.setDuration(500);
                yellowBtn.setAlpha(1f);
                yellowBtn.startAnimation(animation1);
                break;
            case R.id.blueBtn:
                AlphaAnimation animation2 = new AlphaAnimation(0.2f, 1.0f);
                animation2.setDuration(500);
                blueBtn.setAlpha(1f);
                blueBtn.startAnimation(animation2);
                break;
            case R.id.greenBtn:
                AlphaAnimation animation3 = new AlphaAnimation(0.2f, 1.0f);
                animation3.setDuration(500);
                greenBtn.setAlpha(1f);
                greenBtn.startAnimation(animation3);
                break;
            case R.id.redBtn:
                AlphaAnimation animation4 = new AlphaAnimation(0.2f, 1.0f);
                animation4.setDuration(500);
                redBtn.setAlpha(1f);
                redBtn.startAnimation(animation4);
                break;
        }

    }

}

我想根据点击事件在 4 个按钮上应用 setAlpha() 函数。下面是我的代码。我准备了一个 4 个数组，其中包含所有 ID。但是 setAlpha() 会抛出错误。有什么建议吗？

错误:找不到符号方法setAlpha(float)

Android:错误:找不到符号方法 setAlpha(float)。 setAlpha() 不适用于带有偏移量的数组。

Answer 1

因为您必须在 randomTile 函数中对 View 对象调用 setAlpha(1f) 和 startAnimation(animationG)。现在您正在 String 对象上调用这些函数。