Java 如何将按钮放置在相对布局的中心？

我正在尝试在中心应用程序上添加一个按钮。。。 有人能给我解释一下这个代码到底在做什么吗

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

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这段代码的作用是

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

上面的线告诉视图只占用所需的空间

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

以上两行告诉LayoutManager在水平和垂直方向上保持此视图居中

你应该读一些关于和

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我希望它能帮助您

只需在家长中使用android:layout\u centerInParent=“true”或RelativeLayout.CENTER\u即可

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);