RelativeLayout动态布局

居中
https://blog.51cto.com/u_16213317/13014609

// 获取 TextView 和 RelativeLayout 的引用
    TextView myTextView = findViewById(R.id.myTextView);
    RelativeLayout layout = findViewById(R.id.relativeLayout);

    // 创建布局参数对象
    RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(
            RelativeLayout.LayoutParams.WRAP_CONTENT,
            RelativeLayout.LayoutParams.WRAP_CONTENT
    );

    // 设置居中参数
    params.addRule(RelativeLayout.CENTER_IN_PARENT, RelativeLayout.TRUE);

    // 设置布局参数
    myTextView.setLayoutParams(params);