Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string:　が解決できない。

前提・実現したいこと

JTextFieldに文字を入れるとこのエラーが出ます。対処法が本当に分からないので教えていただきたいです。

発生している問題・エラーメッセージ

Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string: "tokyo"
	at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:68)
	at java.base/java.lang.Integer.parseInt(Integer.java:652)
	at java.base/java.lang.Integer.parseInt(Integer.java:770)
	at J13_2.actionPerformed(J13_2.java:59)
	at java.desktop/javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1967)
	at java.desktop/javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2308)
	at java.desktop/javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:405)
	at java.desktop/javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:262)
	at java.desktop/javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:279)
	at java.desktop/java.awt.Component.processMouseEvent(Component.java:6636)
	at java.desktop/javax.swing.JComponent.processMouseEvent(JComponent.java:3342)
	at java.desktop/java.awt.Component.processEvent(Component.java:6401)
	at java.desktop/java.awt.Container.processEvent(Container.java:2263)
	at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:5012)
	at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2321)
	at java.desktop/java.awt.Component.dispatchEvent(Component.java:4844)
	at java.desktop/java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4919)
	at java.desktop/java.awt.LightweightDispatcher.processMouseEvent(Container.java:4548)
	at java.desktop/java.awt.LightweightDispatcher.dispatchEvent(Container.java:4489)
	at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2307)
	at java.desktop/java.awt.Window.dispatchEventImpl(Window.java:2764)
	at java.desktop/java.awt.Component.dispatchEvent(Component.java:4844)
	at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:772)
	at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:721)
	at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:715)
	at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:95)
	at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:745)
	at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:743)
	at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
	at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:742)
	at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
	at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
	at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
	at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
	at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
	at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)

該当のソースコード

Java
1import java.awt.FlowLayout;
2import java.awt.event.ActionEvent;
3import java.awt.event.ActionListener;
4import java.io.DataOutputStream;
5import java.io.InputStream;
6import java.io.ObjectInputStream;
7import java.io.OutputStream;
8import java.net.Socket;
9
10import javax.swing.JButton;
11import javax.swing.JFrame;
12import javax.swing.JTextField;
13
14public class J13_3Client extends JFrame implements ActionListener{
15	
16	JTextField tf1;
17	JTextField tf2;
18	JButton button;
19	
20	int a, b;
21	static String server;
22	static int port;
23	
24	J13_3Client(String title) {
25		super(title);
26        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
27        setSize(150, 150);
28        
29        setLayout(new FlowLayout());
30        
31        tf1 = new JTextField(11);
32        tf2 = new JTextField(11);
33        add(tf1);
34        add(tf2);
35        tf1.setHorizontalAlignment(JTextField.CENTER);
36        tf2.setHorizontalAlignment(JTextField.CENTER);
37        
38        button = new JButton("送信");
39        add(button);
40        button.addActionListener(this);
41            
42        setVisible(true);
43    }
44
45	public static void main(String[] args) {
46		// サーバーとポートを取得
47        server = args[0];
48        port = Integer.parseInt(args[1]);
49		
50		new J13_2("課題3");
51	}
52	
53	public void actionPerformed(ActionEvent e) {
54		String skey = tf1.getText();
55		System.out.println(skey);
56		
57		try {
58            // ソケットを作成
59            Socket s = new Socket(server, port);
60            
61            OutputStream os = s.getOutputStream();
62            DataOutputStream dos = new DataOutputStream(os);
63            dos.writeUTF(skey);
64
65            // サーバーから結果を読み取る
66            InputStream is = s.getInputStream();
67            ObjectInputStream ois = new ObjectInputStream(is);
68            Object o = ois.readObject();
69
70            // 結果を表示
71            if(o == null) {
72            	tf2.setText("該当なし");
73            }else {
74            	tf2.setText(o.toString());
75            }
76
77            // ソケットをクローズ
78            s.close();
79		} catch (Exception ee) {
80            ee.printStackTrace();
81		}
82	}
83}