检测布局中的第一个按钮

Question

我正试图解决这个难题：“如何将列表中的其余按钮放在第一个按钮下。”

为了解决这个问题，我试图设置一个布尔值来检测第一个按钮，并在下面的任何内容上应用规则，但是button1似乎每次都在button0的顶部。

我在下面列出了MainActivity。布局xml只有一个相对布局。

public class MainActivity extends Activity implements View.OnClickListener {

private ArrayList<Category> categories = new ArrayList<Category>();
private ArrayList<Button> buttons = new ArrayList<Button>();
private boolean firstButton = true;

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

    RelativeLayout relLayout = (RelativeLayout) findViewById(R.id.mainLayout);

    categories.add(new Category("Mobility",CategoryTypes.MOBILITY));
    categories.add(new Category("Flexibility",CategoryTypes.FLEXIBILITY));
    categories.add(new Category("Mobility",CategoryTypes.MOBILITY));
    categories.add(new Category("Flexibility",CategoryTypes.FLEXIBILITY));
    categories.add(new Category("Mobility",CategoryTypes.MOBILITY));
    categories.add(new Category("Mobility",CategoryTypes.MOBILITY));

    for (int i = 0; i < 6; i++)
    {
        makeButton(this, "Buttons"+i,i);
    }

    for (int i = 0; i < buttons.size(); i++)
    {
        addButtonToLayout(buttons.get(i),relLayout,i);
        System.out.println(buttons.get(i).getLayoutParams());
    }
}

//This method constructs a button object, sets its text, id and an OnClickListener. Finally adds the buttons to buttons arraylist
void makeButton (Context context, String buttonText, int id)
{
    Button button = new Button(context);
    button.setText(buttonText);
    button.setId(id);
    button.setOnClickListener(this);

    buttons.add(button);
    System.out.println(button.getId());
}

//Method to add button to layout. The LayoutParams are used to add the rule that the buttons should be underneath each other.
void addButtonToLayout (Button button, RelativeLayout layout, int index)
{
    RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, RelativeLayout.LayoutParams.WRAP_CONTENT);
    RelativeLayout.LayoutParams paramsForSecondButton = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, RelativeLayout.LayoutParams.WRAP_CONTENT);

    if (firstButton)
    {
        firstButton = false;
        System.out.println(buttons.get(index).getText());
        //TODO: [BUG] Doesn't add the first button for some reason.
    }
    else if (!firstButton)
    {
        params.addRule(RelativeLayout.BELOW, buttons.get(index-1).getId());
    }

    //paramsForSecondButton.addRule(RelativeLayout.BELOW, buttons.get(0).getId());

    //params.addRule(RelativeLayout.BELOW, buttons.get(index).getId());
    button.setLayoutParams(params);
   // buttons.get(1).setLayoutParams(paramsForSecondButton);

    layout.addView(button);
}

这是布局的图像：

Answer 1

answer类似的问题可以帮助您。

  

您失败的原因是您使用的是ID。 Android使用“保留”ID来处理应用程序的常规内容区域。

     

使用您的代码，我能够为每个ID添加1000并生成预期结果。

以这种方式定位按钮也不是一个好主意。除非你有理由，否则LinearLayout将以计算时间的一半价格完成工作。

Answer 2

在这种情况下你试过了吗？

if (firstButton)
{         
    firstButton = false;
    params.addRule(RelativeLayout.ALIGN_PARENT_TOP);
}
else if (!firstButton)
{
    params.addRule(RelativeLayout.BELOW, buttons.get(index-1).getId());
}