Retrofit: Retrofit.Builder.baseUrl does not support "localhost"

[Singwai]

    public static Retrofit getRetrofit() {
        return new Retrofit.Builder()
                .baseUrl("localhost:8888")
                .addConverterFactory(GsonConverterFactory.create())
                .client(RetrofitApi.getOkHttpClient())
                .build();
    }

I chased the library I think here is where the null return.

   HttpUrl parse(HttpUrl base, String input) {
      int pos = skipLeadingAsciiWhitespace(input, 0, input.length());
      int limit = skipTrailingAsciiWhitespace(input, pos, input.length());

      // Scheme.
      int schemeDelimiterOffset = schemeDelimiterOffset(input, pos, limit);
      if (schemeDelimiterOffset != -1) {
        if (input.regionMatches(true, pos, "https:", 0, 6)) {
          this.scheme = "https";
          pos += "https:".length();
        } else if (input.regionMatches(true, pos, "http:", 0, 5)) {
          this.scheme = "http";
          pos += "http:".length();
        } else {
          return null; // Not an HTTP scheme.
        }
      } else if (base != null) {
        this.scheme = base.scheme;
      } else {
        return null; // No scheme.
      }

12-26 17:57:40.902 2225-2303/io.softape.erhuo E/AndroidRuntime: FATAL EXCEPTION: AsyncTask #1 Process: io.softape.erhuo, PID: 2225 java.lang.RuntimeException: An error occured while executing doInBackground() at android.os.AsyncTask$3.done(AsyncTask.java:300) at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355) at java.util.concurrent.FutureTask.setException(FutureTask.java:222) at java.util.concurrent.FutureTask.run(FutureTask.java:242) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587) at java.lang.Thread.run(Thread.java:818) Caused by: java.lang.IllegalArgumentException: Illegal URL: localhost:8888 at retrofit.Retrofit$Builder.baseUrl(Retrofit.java:304) at io.softape.erhuo.api.retrofit.util.RetrofitApi.getRetrofit(RetrofitApi.java:41) at io.softape.erhuo.api.retrofit.util.RetrofitApi.<init>(RetrofitApi.java:36) at io.softape.erhuo.api.asycnTask.NetworkGetPostTaskWithEndpoint.doInBackground(NetworkGetPostTaskWithEndpoint.java:46) at io.softape.erhuo.api.asycnTask.NetworkGetPostTaskWithEndpoint.doInBackground(NetworkGetPostTaskWithEndpoint.java:26) at android.os.AsyncTask$2.call(AsyncTask.java:288) at java.util.concurrent.FutureTask.run(FutureTask.java:237) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)  at java.lang.Thread.run(Thread.java:818) 

Here is the exception.

[swankjesse]

Try adding http:// as a prefix, like http://localhost:8888/.