在java代码中控制UI界面

public class MainActivity extends AppCompatActivity {
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //setContentView(R.layout.activity_main);
        FrameLayout frameLayout=new FrameLayout(this);
        frameLayout.setBackgroundResource(R.mipmap.bg);
        setContentView(frameLayout);
        TextView text1=new TextView(this);
        text1.setText("开始游戏");
        text1.setTextSize(TypedValue.COMPLEX_UNIT_SP,18);
        text1.setTextColor(Color.rgb(17,85,114));
        FrameLayout.LayoutParams params=new FrameLayout.LayoutParams(
                ViewGroup.LayoutParams.WRAP_CONTENT,
                ViewGroup.LayoutParams.WRAP_CONTENT);
        params.gravity=Gravity.CENTER;
        text1.setLayoutParams(params);
        text1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                new AlertDialog.Builder(MainActivity.this).setTitle("系统提示")
                .setMessage("游戏有风险，进入需谨慎，真的确定要进入？")
                .setPositiveButton("确定",
                        new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {
 
                                Log.i("桌面台球","进入游戏");
 
                            }
                            }).setNegativeButton("退出",
                        new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                Log.i("桌面台球","退出游戏");
                                finish();
                            }
                        }).show();
            }
        });
        frameLayout.addView(text1);
    }
}