使用 ProgressBar.setProgressDrawable 的问题

Question

对具有自定义颜色的 ProgressBar 使用 setProgressDrawable 对我们来说并不能以正确的方式工作。我们在 ListView 的行中使用进度条，但仅当列表中存在多个元素时才会显示进度。如果只有一个元素，进度条为空。

CursorAdapter.java:

public class CursorAdapter extends SimpleCursorAdapter {
    public CursorAdapter(Context context, int layout, Cursor c, String[] from,
            int[] to) {
        super(context, layout, c, from, to);
    }

    public void bindView(View view, Context context, Cursor cursor) {
        super.bindView(view, context, cursor);
        updateProgressbar(view, cursor);
    }

    /**
     * This method updates the progressbar using the "numberpages" and
     * "currentpage" values. 
     */
    private void updateProgressbar(View view, Cursor cursor) {
        ProgressBar progressBar = (ProgressBar) view
                .findViewById(R.id.progressbarHorizontal);

        progressBar.setProgressDrawable(view.getResources().getDrawable(
                R.drawable.greenprogress));

        progressBar.setMax(cursor.getInt(cursor.getColumnIndex("numberpages")));
        progressBar.setProgress(cursor.getInt(cursor
                .getColumnIndex("currentpage")));
    }

}

/res/drawable/greenprogress.xml:

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:id="@android:id/background">
    <shape>
        <corners android:radius="5dip" />
        <gradient
                android:startColor="#ff9d9e9d"
                android:centerColor="#ff5a5d5a"
                android:centerY="0.75"
                android:endColor="#ff747674"
                android:angle="270"
        />
    </shape>
</item>

<item android:id="@android:id/secondaryProgress">
    <clip>
        <shape>
            <corners android:radius="5dip" />
            <gradient
                    android:startColor="#80ffd300"
                    android:centerColor="#80ffb600"
                    android:centerY="0.75"
                    android:endColor="#a0ffcb00"
                    android:angle="270"
            />
        </shape>
    </clip>
</item>

<item android:id="@android:id/progress">
    <clip>
        <shape>
            <corners
                android:radius="5dip" />
            <gradient
                android:startColor="#33FF33"
                android:endColor="#008000"
                android:angle="270" />
        </shape>
    </clip>
</item>

</layer-list>

这段代码有什么问题，为什么只有当列表中有多个元素时它才起作用？如果没有设置自定义 ProgressBar 样式，一切都会正常运行。 setProgressDrawable 方法似乎会出现问题。

谢谢你帮助我们。

Answer 1

private void updateProgressbar(View view, Cursor cursor) {
        ProgressBar progressBar = (ProgressBar) view
                .findViewById(R.id.progressbarHorizontal);

        progressBar.setProgressDrawable(view.getResources().getDrawable(
                R.drawable.greenprogress));

> progressBar.setProgress(1); "Add this statement before setting the progress.."

        progressBar.setMax(cursor.getInt(cursor.getColumnIndex("numberpages")));
        progressBar.setProgress(cursor.getInt(cursor
                .getColumnIndex("currentpage")));
    }