Android的兼容性我使用一個兼容性類的ExceptionInInitializerError

Question

建立一個用戶代理字符串：

public abstract class Compatibility { 

    private static int sdkInt = 0; 

    private static Compatibility instance; 

    public static Compatibility getInstance(){ 
     if (instance!=null) return instance; 

     try { sdkInt = Integer.parseInt(Build.VERSION.SDK); } catch (Exception e) { 
      sdkInt = 3; 
     } 
     if (sdkInt<4) { 
      instance = new CompatibilityAPI3(); 
     } else { 
      instance = new CompatibilityAPI4(); 
     } 
     return instance; 
    } 

    public int getSdkInt(){ 
     return sdkInt; 
    } 

    public abstract String getUa(); 

} 


public class CompatibilityAPI3 extends Compatibility { 
    @Override 
    public String getUa() { 
     return "unknown|unknown|"+Build.DEVICE+"|"+Build.PRODUCT+"|"+Build.BRAND+"|"+Build.VERSION.SDK;  
    } 
} 


public class CompatibilityAPI4 extends Compatibility { 
    @Override 
    public String getUa() { 
     return Build.MANUFACTURER+"|"+Build.MODEL+"|"+Build.DEVICE+"|"+Build.PRODUCT+"|"+Build.BRAND+"|"+Build.VERSION.SDK; 
    } 
} 

我看到這個錯誤發生在某些設備上：

java.lang.ExceptionInInitializerError 
.... 
Caused by: java.lang.NoSuchFieldError: ? 
at ...CompatibilityAPI4.getUa(CompatibilityAPI4.java:8) 

我在做什麼錯？

Answer 1

使用反射。參見：determine API level for platforms < 1.6