Log.println-＆GT;优先参数？

Question

上下文

println（int priority，String tag，String msg）

我想知道'priority'参数。它可以采用以下值：Log.VERBOSE，LOG.WARN等，如Log类中所定义：

public static final int ASSERT = 7 
public static final int DEBUG = 3 
public static final int ERROR = 6 
public static final int INFO = 4 
public static final int VERBOSE = 2 
public static final int WARN = 5

问题

为什么不能简单地使用直的整数值并且必须使用定义的public static final int value枚举？

示例：

Log.println(5,"HI","HI"); //-> can`t    
Log.println(2,"HI","HI"); //-> can`t    
Log.println(Log.VERBOSE,"HI","HI");// -> can    
Log.println(Log.WARN,"HI","HI") //-> can

......和其他例子：

public class MainActivity extends AppCompatActivity  {
public static final int A = 7;

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

    Log.println(A,"HI","HI"); // ->can`t
    Log.println(2,"HI","HI"); // ->can`t
    Log.println(Log.VERBOSE,"HI","HI"); // ->can
}

为什么你不能写Log.println(2,"HI","HI")这些都是整数...