Question

这是Annotation类

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface InjectExtra {
    public String value();
}

以下是处理Annotation课程的课程：InjectActivity：

public class InjectActivity extends Activity {
   protected void onCreate(final Bundle savedInstanceState) {
      super.onCreate(savedInstanceState); 

      handleAnnotation();
   }

   private void handleAnnotation(){
      final Field[] fields = getClass().getDeclaredFields();
      Bundle extras = getIntent().getExtras(); //TODO here always null!!why?

      if(fields == null || fields.length <= 0 || extras == null) {
        return;
      }

      for(final Field field : fields) {
        if(field.isAnnotationPresent(InjectExtra.class)) {
          field.setAccessible(true);

          final InjectExtra injectExtra = field.<InjectExtra>
            getAnnotation(InjectExtra.class); 

          field.set(object, extras.get(injectExtra.value()));
        }
      }
   }
}

现在我正在尝试使用InjectActivity：

public class SimpleActivity extends InjectActivity{
  @InjectExtra("id")
  private String id;

  protected void onCreate(final Bundle savedInstanceState) {
    super.onCreate(savedInstanceState); 

    ...
  }
}

当我尝试开始此活动时，它不起作用：

Intent i = new Intent(currentActivity.this,SimpleActivity.class);
i.putExtra("id", "kai");
startActivity(i);

这是因为getIntent().getExtras()中的InjectActivity始终为null。但是，当我将方法handleAnnotation从InjectActivity移动到SimpleActivity时，它就可以了！

有人能帮助我吗？

Answer 1

尝试替换代码的和平：

Intent i = new Intent(currentActivity.this,SimpleActivity.class);
i.putExtra("id", "kai");
startActivity(i);

这种代码安静：

Intent i = new Intent(currentActivity.this,SimpleActivity.class);
Bundle bundle = new Bundle();
bundle.putString("id", "kai");
i.putExtras(bundle);
startActivity(i)

父类中的Android getIntent（）返回null

1 个答案: