Android: why setVisibility(View.GONE); or setVisib

问题:

I want my DatePicker and the button to be invisible in the begining. And when I press my magic button I want to setVisibility(View.Visible);

The problem here is when I setVisibility(View.GONE) or setVisibility(View.INVISIBLE) nothing changes and the component is still visible.

final DatePicker dp2 = (DatePicker) findViewById(R.id.datePick2);
final Button btn2 = (Button) findViewById(R.id.btnDate2);

dp2.setVisibility(View.GONE);
dp2.setVisibility(View.INVISIBLE);
btn2.setVisibility(View.GONE);
btn2.setVisibility(View.INVISIBLE);

btn2.setOnClickListener(new View.OnClickListener() {
    public void onClick(View arg0) {
        TextView txt2 = (TextView) findViewById(R.id.txt2);
        txt2.setText("You selected " + dp2.getDayOfMonth()
            + "/" + (dp2.getMonth() + 1) + "/" + dp2.getYear());
    }
});

回答1:

I see quite a few things wrong. For starters, you don't have your magic button defined and there is no event handler for it.

Also you shouldn't use:

dp2.setVisibility(View.GONE);
dp2.setVisibility(View.INVISIBLE); 

Use only one of the two. From Android documentation:

View.GONE This view is invisible, and it doesn't take any space for layout purposes.

View.INVISIBLE This view is invisible, but it still takes up space for layout purposes.

In your example, you are overriding the View.GONE assignment with the View.INVISIBLE one.

---

Try replacing:

final DatePicker dp2 = new DatePicker(this)

with:

DatePicker dp2 = (DatePicker) findViewById(R.id.datePick2);  

Similarly for other widgets:

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        LinearLayout ll = new LinearLayout(this);
        ll.setOrientation(LinearLayout.VERTICAL);

        final DatePicker dp2 = new DatePicker(this);
        final Button btn2 = new Button(this);
        final Button magicButton = new Button(this);
        final TextView txt2 = new TextView(TestActivity.this);

        dp2.setVisibility(View.GONE);
        btn2.setVisibility(View.GONE);
        btn2.setText("set Date");

        btn2.setOnClickListener(new View.OnClickListener() {
            public void onClick(View arg0) {
                txt2.setText("You selected "
                    + dp2.getDayOfMonth() + "/" + (dp2.getMonth() + 1) 
                    + "/" + dp2.getYear());
            }
        });

        magicButton.setText("Magic Button");
        magicButton.setOnClickListener(new View.OnClickListener()    
            public void onClick(View arg0) {
                dp2.setVisibility(View.VISIBLE);
                btn2.setVisibility(View.VISIBLE);
            }
        });

    ll.addView(dp2);
    ll.addView(btn2);
    ll.addView(magicButton);
    ll.addView(txt2);

    setContentView(ll);
}

回答2:

You can think it as a CSS style visibility & display.

<div style="visibility:visible; display:block">
    This is View.VISIBLE : Content is displayed normally.
</div>

<div style="visibility:hidden; display:block">
    This is View.INVISIBLE : Content is not displayed, but div still takes up place, but empty.
</div>

<div style="display:none">
    This is View.GONE : Container div is not shown, you can say the content is not displayed.
</div>

回答3:

First see your code:

dp2.setVisibility(View.GONE);
dp2.setVisibility(View.INVISIBLE);
btn2.setVisibility(View.GONE);
btn2.setVisibility(View.INVISIBLE);

Here you set both visibility to same field so that's the problem. I give one sample for that sample demo

回答4:

Today I had a scenario, where I was performing following action:

myViewGroup.setVisibility(View.GONE);

Right on the next frame I was performing an if check somewhere else for visibility state of that view. And guess what? The following condition was passing:

if(myViewGroup.getVisibility() == View.VISIBLE) {
    // this if check was fulfilled magically
}

Placing breakpoints you see, that visibility changes to GONE, but right on the next frame it magically becomes VISIBLE. I was trying to understand how the hell this could happen.

Turns out there was an animation applied to this view, which internally caused the view to change it's visibility to VISIBLE until finishing the animation:

public void someFunction() {
    ...
    TransitionManager.beginDelayedTransition(myViewGroup);
    ...

    myViewGroup.setVisibility(View.GONE);
}

If you debug, you'll see that myViewGroup indeed changes its visibility to GONE, but right on the next frame it would again become visible in order the animation to run.

So, if you come across with such a situation, make sure you are not performing an if check in midst of animating the view.

You can remove all animations on the view via View.clearAnimation().

回答5:

View.GONE This view is invisible, and it doesn't take any space for layout purposes.

View.INVISIBLE This view is invisible, but it still takes up space for layout purposes.

dp2.setVisibility(View.GONE);
dp2.setVisibility(View.INVISIBLE);
btn2.setVisibility(View.GONE);
btn2.setVisibility(View.INVISIBLE);

回答6:

View.GONE makes the view invisible without the view taking up space in the layout. View.INVISIBLE makes the view just invisible still taking up space.

You are first using GONE and then INVISIBLE on the same view.Since, the code is executed sequentially, first the view becomes GONE then it is overridden by the INVISIBLE type still taking up space.

You should add button listener on the button and inside the onClick() method make the views visible. This should be the logic according to me in your onCreate() method.

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_setting);

    final DatePicker dp2 = (DatePicker) findViewById(R.id.datePick2);
    final Button btn2 = (Button) findViewById(R.id.btnDate2);

    dp2.setVisibility(View.INVISIBLE);
    btn2.setVisibility(View.INVISIBLE);

    bt2.setOnClickListener(new View.OnCLickListener(){ 
    @Override
    public void onClick(View view)
    {
        dp2.setVisibility(View.VISIBLE);
        bt2.setVisibility(View.VISIBLE);
    }
  });
}

I think this should work easily. Hope this helps.

回答7:

Because you set visibility either true or false. try that setVisible(0) to visible true . and setVisible(4) to visible false.