Error:(28) Error: This class should provide a default constructor (a public constructor with no arguments) (myclassname.HelpDialog) [Instantiatable]

Question

在调试模式下编译时一切正常。但是在发布配置中编译时，出现以下错误：

Error:(28) Error: This class should provide a default constructor (a public constructor with no arguments) (myclassname.HelpDialog) [Instantiatable]

这是代码

public class HelpDialog extends Dialog {

    Activity mActivity;
    Button btn_go_back;   

    public HelpDialog(Activity mactivity) {
        super();
        this.mActivity = mactivity;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.dialog_help);   

        btn_go_back = (Button)findViewById(R.id.btn_help_go_back);

        btn_go_back.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                dismiss();
            }
        });
    }
}

Answer 1

添加这个兄弟：

public HelpDialog( ){ 
  super(null);
}