setVisibility(View.GONE) 不起作用？ 为什么？

Question

I can swear to anything you like that this code was working on my previous app that I was working on, but now it wont do anything at all, It should be a simple thing I must have forgot before using this code but I dont know what it was.

what I am trying to accomplish is to make the button gone and make the layout visible.

here is my xml:

    <?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#E675E8">

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:background="#FFFFFF"
        android:layout_marginBottom="2dp">

        <LinearLayout
            android:orientation="horizontal"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_weight="1.0">

            <ImageView
                android:src="@drawable/natlilandbarpic"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"/>

        </LinearLayout>

        <Button
            android:layout_width="50dp"
            android:layout_height="wrap_content"
            android:background="@drawable/drawbtn"
            android:id="@+id/drawbutton"
            android:visibility="visible"/>

    </LinearLayout>

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="right"
        android:layout_weight="1.0">

        <WebView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:text="Text"
            android:id="@+id/webView"/>

        <LinearLayout
            android:orientation="vertical"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:visibility="gone"
            android:gravity="left"
            android:layout_marginLeft="100dp"
            android:id="@+id/drawlist">

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button"/>

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button"/>

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button"/>

        </LinearLayout>

    </RelativeLayout>

</LinearLayout>

here is my activity:

    public class MainActivity extends Activity 
    {
        private WebView webView;
        private Button drawbutton;
        private LinearLayout drawlist;
        
        @Override
        protected void onCreate(Bundle savedInstanceState)
        {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);
            getActionBar().hide();
            
            
            webView = (WebView) findViewById(R.id.webView);
            webView.getSettings().setJavaScriptEnabled(true);
            webView.loadUrl("");
            webView.setWebViewClient(new WebViewClient(){
    
                    @Override
                    public boolean shouldOverrideUrlLoading(WebView view, String url){
                        view.loadUrl(url);
                        return true;
                    }
                });
            }
                
        public void addListenerOnButton() {
            
            drawbutton = (Button) findViewById(R.id.drawbutton);
            drawbutton.setOnClickListener(new OnClickListener() {
                    @Override
                    public void onClick(View p) {   
                    drawbuttonprop(p);
                    }
                });
            drawlist = (LinearLayout) findViewById(R.id.drawlist);
        }
        public void drawbuttonprop(View view)
        {
            drawbutton.setVisibility(View.GONE);
            drawlist.setVisibility(View.VISIBLE);
        }

}

Any kind of help and tricks to make it work I would be appreciate it.

Answer 1

First of All i guess the reason why you re experiencing that because you are not calling the function addListenerOnButton(), so you have to call it in your oncreate, secondly you are calling the function which also sets the drawlist visibility to visible after the button is clicked but you have to be aware that you are trying to find the reference of the drawlist after clicking the button and that will cause the app to crash, so you need to put this line of code "drawlist = (LinearLayout) findViewById(R.id.drawlist);" along with first findViewById of the button, hope this helps.