如何在相對布局的中心放置一個按鈕？

Question

我正在嘗試在中心應用程序上放置一個按鈕...有人可以向我解釋這段代碼究竟在做什么嗎？

RelativeLayout.LayoutParams BD = new RelativeLayout.LayoutParams(
            RelativeLayout.LayoutParams.WRAP_CONTENT,
            RelativeLayout.LayoutParams.WRAP_CONTENT
    );
    BD.addRule(RelativeLayout.CENTER_HORIZONTAL);
    BD.addRule(RelativeLayout.CENTER_VERTICAL);

Answer 1

該代碼的作用是

RelativeLayout.LayoutParams BD = new RelativeLayout.LayoutParams(
        RelativeLayout.LayoutParams.WRAP_CONTENT,
        RelativeLayout.LayoutParams.WRAP_CONTENT
);

上面的線告訴視圖僅占據所需的空間。

BD.addRule(RelativeLayout.CENTER_HORIZONTAL);
BD.addRule(RelativeLayout.CENTER_VERTICAL);

上面兩行告訴LayoutManager在水平和垂直方向上將此視圖保持在居中位置。

您應該閱讀RelativeLayout和RelativeLayoutParams 。

Answer 2

RelativeLayout relativeLayout;
Button btnNewButton;
relativeLayout = new RelativeLayout(getApplicationContext());
    btnNewButton = new Button(getApplicationContext());
    btnNewButton.setText("Button Text");

    RelativeLayout.LayoutParams BD = new RelativeLayout.LayoutParams(
            RelativeLayout.LayoutParams.WRAP_CONTENT,
            RelativeLayout.LayoutParams.WRAP_CONTENT
    );
    BD.addRule(RelativeLayout.CENTER_HORIZONTAL);
    BD.addRule(RelativeLayout.CENTER_VERTICAL);

    btnNewButton.setLayoutParams(BD);

    relativeLayout.addView(btnNewButton);
    setContentView(relativeLayout);

希望對您有幫助