java - 枚举类型的空指针访问警告

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我的MainActivity代码是

private void updateConnectionState()
      {
              Device localDevice = this.Controller.getConnectedDevice();
              if (localDevice == null)

              updateModelSpinner(localDevice.getType());    //warning at this line          
              str2 = localDevice.getHostName();
              if (!TextUtils.isEmpty(str2))

            }




private void updateSpinner(Device.Type paramType)
      {
        boolean bool = Device.Type.UNKNOWN.equals(paramType);
        int i = 0;
        if (!bool)
          i = 1 + paramTvType.ordinal();
        this.ModelSpinner.setSelection(i);
      }

private void ModelSpinner(Device.Type paramType)
      {
        boolean bool = Device.Type.UNKNOWN.equals(paramType);
        int i = 0;
        if (!bool)
          i = 1 + paramType.ordinal();
        this.ModelSpinner.setSelection(i);
      }

我的枚举类是

public class Device {

    private Type type = Type.A_LOGIC;   

    public static Type getTypeForId(int paramInt)
      {
        switch (paramInt)
        {
        default:
          return Type.A_LOGIC;      
        case 0:
          return TvType.B_LOGIC;
        case 1:
          return TvType.A_LOGIC;
        case 2:
          return TvType.D_LOGIC;
        case 3:
          return TvType.E_LOGIC;
        case 4:
        }
        return TvType.F_LOGIC;          
      }

  public void setType(Type paramType)
      {
        this.Type = paramType;
      }

     public enum Type
     {       
         A_LOGIC("A_LOGIC"),                
         B_LOGIC ("B_LOGIC" ),      
         C_LOGIC ("C_LOGIC"), 
         D_LOGIC("D_LOGIC"),
         E_LOGIC ("E_LOGIC"),
        UNKNOWN("UNKNOWN");

        private String object;

        TvType(String localobj)
        {
            this.object; = localobj;
        }       
        public String getLetter()
        {
          return this.object;;
        }       
     }

 public Type getType()
      {
        return this.type;
      }

在我的主要 Activity 中，方法中调用类型为

updateSpinner(localDevice.getType());

但这里显示警告为

Null pointer access: The variable localTVDevice can only be null at this location

并在该行抛出空点错误。我对枚举的概念很陌生，所以请告诉我为什么它会抛出此错误。我提到了堆栈溢出，但找不到答案。

Answer 1

从您的代码中:

Device localDevice = this.Controller.getConnectedDevice();
if (localDevice == null)

updateModelSpinner(localDevice.getType());

由于 if 没有 {}，此代码类似于:

Device localDevice = this.Controller.getConnectedDevice();
if (localDevice == null) {
    updateModelSpinner(localDevice.getType());
}

因此出现警告

修复:

Device localDevice = this.Controller.getConnectedDevice();
if (localDevice != null) {
    updateModelSpinner(localDevice.getType());
    // more code using localDevice
}