java.lang.NullPointerException：尝试通过Android Studio中的OutputStream发送数据时

Question

当我尝试发送字符串错误时显示为：

  

引起：java.lang.NullPointerException：尝试调用虚方法＆＃39; void java.io.OutputStream.write（byte []）＆＃39;在空对象引用上

(BaseApp)this.getApplicationContext()).my.BTconnect();
((BaseApp)this.getApplicationContext()).my.beginStart();
String s = "w";
try {
  outputStream.write(s.getBytes());
} catch (IOException e) {
  e.printStackTrace();
}

Answer 1

您应该初始化输出流。

String file_stream = "C:\Users\s.rodic\eclipse\test.txt";
String s = "w";
try {
    OutputStream outputStream = new FileOutputStream(file_stream); //file_stream is your file location
    outputStream.out(s.getBytes());
} catch (IOException e) {
    e.printStackTrace();
}

Answer 2

我认为您的问题在写http或https，如果您希望与您的服务器连接，请尝试只写：http

String login_url = "http:`stack.com`

希望能帮到你！