java - 标识符预期困惑

Question

我正在做一个项目，但出现标识符错误。我不确定如何解决此问题。它在第五行。谢谢您的帮助! :)

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.RelativeLayout;

public class Activity extends AppCompatActivity {

    public void clickFunction (RelativeLayout) {
        RelativeLayout theRelativeLayout = (RelativeLayout)findViewById(R.id.backgroundfirst);
        theRelativeLayout.setBackgroundResource(R.drawable.backgroundsecond);
    }

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

Answer 1

public void clickFunction (RelativeLayout)

这是无效的方法签名，您只需要定义参数的类型，还必须定义其名称:

public void clickFunction (RelativeLayout relativeLayout)