类型无法从类型View静态引用非静态方法setVisibility（int）

Question

I keep getting the following error in Eclipse:

Type Cannot make a static reference to the non-static method setVisibility(int) from the type View

My code is:

package com.example.testing;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends Activity {

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
}

public void onLoveButtonClicked(View view) {
    TextView haikuTextView = (TextView) findViewById(R.id.haikuTextView);
    TextView.setVisibility(View.VISIBLE); //error here
}
 }

I'm only a beginner at java so I don't know what's causing that problem. I have googled the error but I don't get anything that helps me.

Answer 1

You need to use:

haikuTextView.setVisibility(View.VISIBLE); 

TextView is the class and haikuTextView is your variable. You cannot change the visibility of an entire class. But you can change the visibility of your variable.

---

When you wrote:

<TextView
    android:id="@+id/haikuTextView"
    ... />

you created one instance of the TextView class. You can create a lot of instances of the TextView class, but when you want to change some feature about a particular in one instance you have to specify which TextView you want to change.

When you wrote TextView.setVisibility() you tried to change every TextView . Now the TextView class doesn't have a method setVisibility() to change every TextView , but it does have setVisibilty() to change one instance.

So
When you try to access every TextView with TextView.setVisibility() this is a "static reference" but, like I said, there is no method to call setVisibility() every TextView .

If you use haikuTextView.setVisibilty() to change the visibility of one instance, this will work because this is "non-static method" exists.

Answer 2

To expand on Sam's answer:

TextView is a class; it's also a subclass of the View class. When you refer to static members of a class, you do "classname.method(...)" or "classname.field"; when you say "TextView.setVisibility", you're making a "static reference" to the method "setVisibility" in the "View" class, which is inherited by the TextView class. Thus, the error message: Cannot make a static reference to the non-static method setVisibility(int) from the type View. Because the setVisibility method isn't a static method; it's an ordinary method.

Ordinary methods have to be referred to relative to a specific instance of the class. Since haikuTextView is an instance of TextView; you can say:

haikuTextView.setVisibility(View.VISIBLE);

Is that clear?

Answer 3

It should be:

textView.setVisibility(View.VISIBLE);//A small t instead of a capital T.

Best of Luck