Android 如何将导航栏更改为三点模式？

我想将导航栏设置为三个点，如下所示：

Android开发者网站展示了如何完全删除导航栏（全屏模式），但没有展示如何启用此模式

我该怎么做？

请参考此

基本上，在

setContentView

// This example uses decor view, but you can use any visible view.
View decorView = getActivity().getWindow().getDecorView();
int uiOptions = View.SYSTEM_UI_FLAG_LOW_PROFILE;
decorView.setSystemUiVisibility(uiOptions);

当需要以编程方式显示条形图时，请清除以下标志：

View decorView = getActivity().getWindow().getDecorView();
// Calling setSystemUiVisibility() with a value of 0 clears
// all flags.
decorView.setSystemUiVisibility(0);

请参考这个

基本上，在

setContentView

// This example uses decor view, but you can use any visible view.
View decorView = getActivity().getWindow().getDecorView();
int uiOptions = View.SYSTEM_UI_FLAG_LOW_PROFILE;
decorView.setSystemUiVisibility(uiOptions);

当需要以编程方式显示条形图时，请清除以下标志：

View decorView = getActivity().getWindow().getDecorView();
// Calling setSystemUiVisibility() with a value of 0 clears
// all flags.
decorView.setSystemUiVisibility(0);

请参考这个

基本上，在

setContentView

// This example uses decor view, but you can use any visible view.
View decorView = getActivity().getWindow().getDecorView();
int uiOptions = View.SYSTEM_UI_FLAG_LOW_PROFILE;
decorView.setSystemUiVisibility(uiOptions);

当需要以编程方式显示条形图时，请清除以下标志：

View decorView = getActivity().getWindow().getDecorView();
// Calling setSystemUiVisibility() with a value of 0 clears
// all flags.
decorView.setSystemUiVisibility(0);

请参考这个

基本上，在

setContentView

// This example uses decor view, but you can use any visible view.
View decorView = getActivity().getWindow().getDecorView();
int uiOptions = View.SYSTEM_UI_FLAG_LOW_PROFILE;
decorView.setSystemUiVisibility(uiOptions);

当需要以编程方式显示条形图时，请清除以下标志：

View decorView = getActivity().getWindow().getDecorView();
// Calling setSystemUiVisibility() with a value of 0 clears
// all flags.
decorView.setSystemUiVisibility(0);