java.lang.NumberFormatException

本文介绍了java.lang.NumberFormatException的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我有以下Java代码与cassandra连接。它给出了java.lang.NumberFormatException

I have following java code to connect with cassandra. it is giving java.lang.NumberFormatException

任何想法吗？

package com.retail;

import org.apache.cassandra.thrift.*;
import org.apache.thrift.protocol.*;
import org.apache.thrift.transport.*;

import java.lang.*;

public class ShowKeyspaces {

public static void main(String args[]) throws Exception {

    String host = System.getenv("localhost");
    int port = Integer.parseInt(System.getenv("9160"));

    TSocket socket = new TSocket(host,port);
    TTransport transport = new TFramedTransport(socket);

    TProtocol proto = new TBinaryProtocol(transport);
    transport.open();

    Cassandra.Client client = new Cassandra.Client(proto);

    System.out.println("Version: "+client.describe_version());
    System.out.println("cluster name : "+client.describe_cluster_name());

    transport.close();
    }

}

给出的错误是：

**Exception in thread "main" java.lang.NumberFormatException: null
at java.lang.Integer.parseInt(Unknown Source)
at java.lang.Integer.parseInt(Unknown Source)
at com.retail.ShowKeyspaces.main(ShowKeyspaces.java:14)**

任何想法我应该怎么做？

Any idea how I should go about this???

谢谢！

推荐答案

由于以下原因，您得到了 NumberFormatException ：

You are getting a NumberFormatException because of this line:

int port = Integer.parseInt(System.getenv("9160"));

我认为您尚未将 9160 设置为系统属性，并且 System.getenv（ 9160）返回一个空字符串，即。因此，可以将 9160 设置为环境变量或简单地：

I think you haven't set 9160 as a system property and System.getenv("9160") is returning an empty string, aka "". So either set 9160 as an environment variable or simply:

int port = 9160;

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