回调callback

---

title: 回调callback

参考：

JAVA回调机制(CallBack)详解
一个经典例子让你彻彻底底理解java回调机制

1.新建一个类，声明接口：

public interface GetCodeCallback {    
      void GetCodeCallback(String result);
}

2.实现接口

public abstract class AbstractBlocklyActivity extends AppCompatActivity  implements GetCodeCallback{

@Override
public void GetCodeCallback(String result) {    
       System.out.println("返回来的*--->" + result);
}

在oncreate 中使用

LoggingCodeGeneratorCallback lc = new LoggingCodeGeneratorCallback(this,"我也不知道");
lc.executeMessage(this);

public class LoggingCodeGeneratorCallback implements CodeGenerationRequest.CodeGeneratorCallback {
    private static GetCodeCallback callbackd; //使用静态，不然会是空指针异常。
    protected final String mTag;
    protected final Context mContext;

    public LoggingCodeGeneratorCallback(Context context, String loggingTag) {
        mTag = loggingTag;
        mContext = context;
    }

    public void executeMessage(GetCodeCallback callBack) {
        System.out.println("小王问的问题--->");

        this.callbackd = callBack;
    }

    @Override
    public void onFinishCodeGeneration(String generatedCode) {
        // Sample callback.
        if (generatedCode.isEmpty()) {
            Toast.makeText(mContext,
                "Something went wrong with code generation.", Toast.LENGTH_LONG)
                 .show();
        } else {
            Log.d(mTag, "code: " + generatedCode);
            //            Toast.makeText(mContext, generatedCode, Toast.LENGTH_LONG).show();
            callbackd.GetCodeCallback(generatedCode);
        }
    }
}