GridLayout中只有一个按钮被取消

Question

我试图生成一个网格式的按钮列表。它有效，除了其中一个按钮，它是唯一一个没有drawable的按钮。我不确定如何使其与其他按钮对齐。

以下是类方法：

// test values
private static final int CURRENT_LEVEL = 8;
private static final int LEVEL_CAP = 20;

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

    generateList();
}

public void generateList() {
    GridLayout layout = (GridLayout)findViewById(R.id.mainLayout);
    layout.setColumnCount(5);

    for (int i = 1; i <= LEVEL_CAP; i++) { // for every level there is

        Button btn = new Button(this);

        // 200x200 size
        btn.setLayoutParams(new LinearLayout.LayoutParams(200, 200));
        btn.setTextSize(14);

        if (i < CURRENT_LEVEL) { // already completed the level
            setTopDrawable(btn, R.drawable.ic_checkmark_holo_light, i);

        } else if (i == CURRENT_LEVEL) { // current level being completed
            //setTopDrawable(btn, 0, i); // gets the same result as the line below
            btn.setText(String.valueOf(i));

        } else if (i > CURRENT_LEVEL) { // these are the locked levels
            setTopDrawable(btn, R.drawable.ic_lock_lock, i);
        }

        layout.addView(btn);
    }
}

public Button setTopDrawable(Button btn, int id, int i) {
    // put the drawable with its id = id on top
    btn.setCompoundDrawablesWithIntrinsicBounds(0, id, 0, 0);
    btn.setCompoundDrawablePadding(0);
    btn.setPadding(0, 20, 0, 20);
    btn.setText(String.valueOf(i)); // put the level text under the drawable

    return btn;
}

以下是相关布局：

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context="com.mikeyaworski.whoisthatyoutuber.LevelSelect" >

    <GridLayout
        android:id="@+id/mainLayout"
        android:layout_width="match_parent"
        android:layout_height="match_parent" >
    </GridLayout>
</ScrollView>

这是输出：

如何让按钮8与其他按钮对齐？