Question

我正在为我的应用动态创建按钮，我想将它们随机放在屏幕上。我尝试使用线性布局方法setMargins来定位它们：

按钮创建位于onCreate：

内

    // Create buttons
    for (int i = 0; i < NUMBER_OF_BUTTONS; i++) {
        Button hiddenButton = new Button(this);
        // Set new button properties
        hiddenButton.setId(i);
        hiddenButton.setOnClickListener(setOnClick(hiddenButton));
        // Add the button to the array of buttons
        buttonsArr[i] = hiddenButton;

    }

我有这个函数随机放置它们：

private void placeButtonsOnScreen() {

    Random r = new Random();

    LinearLayout layout = (LinearLayout) findViewById(R.id.ordered_buttons_layout);

    for (int i = 0; i < NUMBER_OF_BUTTONS; i++) {
        final Button hiddenButton = buttonsArr[i];
        // Get random horizontal margin for the button
        LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(
                LinearLayout.LayoutParams.WRAP_CONTENT,
                LinearLayout.LayoutParams.WRAP_CONTENT);
        horizontalMargin = r.nextInt(Math.abs(SCREEN_WIDTH
                - hiddenButton.getWidth()));
        layoutParams.setMargins(horizontalMargin, 50, 0, 0);
        // Add the button to the screen
        layout.addView(hiddenButton, layoutParams);
        Log.d("button width", String.valueOf(hiddenButton.getWidth()));
    }
}

问题是getWidth()函数返回0.我应该怎么做才能将按钮放在屏幕上而不会被屏幕两侧切掉（即减去按钮的宽度）？

Answer 1

您只能在布局传递后获取视图尺寸，因此您调用placeButtons而不是调用：

    getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {

        @Override
        public void onGlobalLayout() {
            placeButtons();
            getViewTreeObserver().removeOnGlobalLayoutListener(this);
        }
    });

更新：

    int btnCount = 10;
    final LinearLayout layout = (LinearLayout) findViewById(R.id.action_bar);
    for (int i = 0; i < btnCount; i++) {
        layout.addView(new Button(this),new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT));
    }
    layout.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {
            layout.getViewTreeObserver().removeOnGlobalLayoutListener(this);

            for(int i = 0; i<layout.getChildCount(); i++) {
                View view = layout.getChildAt(i);
                if(view instanceof Button) {
                    LinearLayout.LayoutParams layoutParams = (LayoutParams) view.getLayoutParams();
                    int horizontalMargin = r.nextInt(Math.abs(SCREEN_WIDTH - view.getWidth()));
                    layoutParams.setMargins(horizontalMargin, 50, 0, 0);
                    view.setLayoutParams(layoutParams);
                }
            }
        }
    });
    layout.requestLayout();

如何随机放置动态创建的按钮？

1 个答案: