创建menu资源文件

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:id="@+id/one"
        android:title="@string/menu"
        />
</menu>

Activity添加点击事件，创建PopupMenu

@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_root_v2);
    View menuImageButton = findViewById(R.id.menuImageButton);
    menuImageButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            showPopupMenu(view);
        }
    });
}

private void showPopupMenu(View view) {
    PopupMenu popup = new PopupMenu(RootActivityV2.this, view);
    popup.getMenuInflater().inflate(R.menu.activity_root, popup.getMenu());
    popup.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
        public boolean onMenuItemClick(MenuItem item) {
            switch(item.getItemId()){
                ...
            }
            return true;
        }
    });

    popup.show();
}