MyClass instance = new MyClass(this);

public class MyClass {
    public Activity activity;

    public MyClass(Activity _activity){
        this.activity = _activity;
    }
}​

TableRow tr_head = new TableRow(this);
tr_head.setId(10);
tr_head.setBackgroundColor(Color.GRAY);
tr_head.setLayoutParams(new LayoutParams(
LayoutParams.FILL_PARENT,
LayoutParams.WRAP_CONTENT));​