Why do I get “must override a superclass method” w

问题:

The following code generates this error message at the public void onClick line.

Multiple markers at this line
- implements android.view.View.OnClickListener.onClick
- The method onClick(View) of type new View.OnClickListener(){} must override a superclass method

I can't understand why. This code is taken from numerous examples I've seen. What can possibly be wrong?

private Button audioButton;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    audioButton = (Button) findViewById(R.id.imageButton1);
    audioButton.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View button) {
            if (button.isSelected()) {
                button.setSelected(false);
            }
            else {
                button.setSelected(true);
            }
        }
    });
}

回答1:

Check the project's properties and verify that Java Compiler -> Compiler compliance level is set to 1.6.

回答2:

This is most likely due to a source code level incompatibility between Java 1.5 and 1.6.

• In Java 5, the @Override annotation requires that the method is actually overriding a method in a superclass.

• In Java 6 and later, the @Override annotation will also be satisfied if the method is implementing an abstract method in a superclass or interface.

So the most likely reason for seeing this in code that you expect to work is that you are compiling Java 6 (or later) code with a Java 5 compiler (or some other compiler with the compiler's source compliance level set to 5).

回答3:

If you set the compiler to 1.6 and still get this error, try to check your imports, because what Eclipse does is that it always try to do this

import android.content.DialogInterface.OnClickListener  

instead of ->

import android.view.View.OnClickListener

That solves my problem.

回答4:

MAVEN USERS If you're using Maven for build it can override the eclipse settings during build. So if you set Eclipse to 1.7 but don't specifically set the Maven JDK build version(which at the time of this writing defaults to 1.5), then it will reset eclipse target compiler back to 1.5. Set the Maven compiler as follows.

    <build>
        ...
        <plugins>
            ....
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.5.1</version>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                </configuration>
            </plugin>
        </plugins>            
    </build>

回答5:

Putting a View.onCLickListener() solved the problem to me. My Java Compiler --> Compiler COmpliance level is already set to 1.6 but still I was having the same problem.

But changing the code

rdBtn.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                onRadioButtonClicked(v);
            }
        });

to

rdBtn.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                onRadioButtonClicked(v);
            }
        });

solved the problem in my case.

回答6:

For me this happened because the Method I wanted to override was package private and I tried to override it from a different package.

Eclipse will additionally put a warning in that case that I didn't notice because of a ton of other warnings

回答7:

Now it's 2018! For easy reference, see screenshot below.