为什么InputStream input=url.openStream();会报错

[Lafite_1039814352]

public static void main (String[] args)throws Exception {
URL url=new URL("http","www.mldnjava.cn",80,"index.html");
InputStream input=url.openStream();
Scanner scan=new Scanner(input);
scan.useDelimiter("\n");
while(scan.hasNext()) {
System.out.println(scan.next());
}
}
用的eclipse

[Lafite_1039814352]

Exception in thread "main" java.net.UnknownHostException: www.mldnjava.cn at java.base/java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:221) at java.base/java.net.PlainSocketImpl.connect(PlainSocketImpl.java:148) at java.base/java.net.Socket.connect(Socket.java:591) at java.base/java.net.Socket.connect(Socket.java:540) at java.base/sun.net.NetworkClient.doConnect(NetworkClient.java:182) at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:474) at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:569) at java.base/sun.net.www.http.HttpClient.<init>(HttpClient.java:242) at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:341) at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:362) at java.base/sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1242) at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1181) at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1075) at java.base/sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:1009) at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1581) at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1509) at java.base/java.net.URL.openStream(URL.java:1117) at try_internet.Try_test.main(Try_test.java:11) 这是报错

[hang199309]

www.mldnjava.cn 这个地址是什么？报错说这个不知道来源？

[verejava]

Java 网络编程 之 HTTP Get Post http://www.verejava.com/?id=17002852927681

[俊逸君故]

同样的情况，结果发现是忘了在AndroidManifest.xml里加<uses-permission android:name="android.permission.INTERNET"/>许可了。。