Extend JTextField to InputStream and action from Button

Question

I have some problems with my code and i would need some help if you can please(and explain it a bit so i can understand in the future:)), so this is my code and what i need is that my JButton to action a shutdown command and the shutdown command to be delayed from the seconds i input in my JTextfield. So my code so far is :

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;


public class Shutdown extends JFrame{
    InputStream text1;
    JButton start;
    String shutdownCmd;

        public Shutdown() {

        this.setTitle("Shutdown When you want");
        setSize(300, 150);
        setResizable(false);
        setLocation(370, 150);
        setLayout(null);

        JLabel desc1 = new JLabel("Time until shutdown : ");
        desc1.setBounds(95, 25, 125, 25);
        add(desc1);

        JTextField text1 = new JTextField();
        text1.setBounds(95, 45, 120, 25);
        text1.setForeground(Color.BLACK);
        text1.setToolTipText("Introdu textu aici");
        add(text1);

        JButton start = new JButton("Start Shudown");
        start.setBounds(95, 75, 120, 25);
        add(start);



        ActionListener eventstart = new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent arg0) {
                // TODO auto- generated method
                String actionstart = arg0.getActionCommand();
                if(actionstart.equals("Start Shudown")){
                    try {
                        ShutdownCmd();
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }

                }

        }; 
        start.addActionListener(eventstart);
}       
        public void ShutdownCmd() throws IOException{
     Runtime runtime = Runtime.getRuntime();
     BufferedReader br=new BufferedReader(new InputStreamReader(text1));
     long a=Long.parseLong(br.readLine());
     Process proc = runtime.exec("shutdown -s -t "+a);
     System.exit(0);
}
}

Thank you or the help in advanced !!! :D

Answer 1

Lots of things jump out at me here, but...

Redeclare text1 as JTextField instead of an InputStream ...

//InputStream text1;
private JTextField text1;

This will allow you to access the field and it's value from anywhere in the class.

Make sure you aren't shadowing the variables when you create the text field...

//JTextField text1 = new JTextField();
text1 = new JTextField(10);

Make use of ProcessBuilder instead of Runtime.getRuntime() . It will make your life easier to deals with parameters much better

ProcessBuilder pb = new ProcessBuilder("shutdown", "-s", "-t", text1.getText());
pb.redirectError();
Process p = pb.start();

The action command will always be null as you never set, so the following will cause you a NullPointerException

String actionstart = arg0.getActionCommand();
if(actionstart.equals("Start Shudown")){

When you create your button, you need to set the action command...

JButton start = new JButton("Start Shudown");
start.setActionCommand("Start Shudown");

Additional suggestions...

• Make use of appropriate layout managers. Even across the same OS, it's possible your application will need to deal with different screen resolutions, DPI, fonts etc...
• Avoid extending directly from top level containers like JFrame . Instead, base you application on something like JPanel . It makes your application for flexible and re-usable.

Answer 2

All you need to do is make the JTextField a field:

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;


public class Shutdown extends JFrame{
    JTextField text1;
    JButton start;
    String shutdownCmd;

        public Shutdown() {

        this.setTitle("Shutdown When you want");
        setSize(300, 150);
        setResizable(false);
        setLocation(370, 150);
        setLayout(null);

        JLabel desc1 = new JLabel("Time until shutdown : ");
        desc1.setBounds(95, 25, 125, 25);
        add(desc1);

        text1 = new JTextField();
        text1.setBounds(95, 45, 120, 25);
        text1.setForeground(Color.BLACK);
        text1.setToolTipText("Introdu textu aici");
        add(text1);

        JButton start = new JButton("Start Shudown");
        start.setBounds(95, 75, 120, 25);
        add(start);



        ActionListener eventstart = new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent arg0) {
                // TODO auto- generated method
                String actionstart = arg0.getActionCommand();
                if(actionstart.equals("Start Shudown")){
                    try {
                        ShutdownCmd();
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }

                }

        }; 
        start.addActionListener(eventstart);
}       
        public void ShutdownCmd() throws IOException{
            Runtime runtime = Runtime.getRuntime();

            long a=Long.parseLong(text1.getText());
            Process proc = runtime.exec("shutdown -s -t "+a);
            System.exit(0);
        }
}

If it's global, you can use it in any of this object's functions, so you can get the Text from the textField from anywhere you want inside your JFrame Object.

I hope this is what you want to do. If its not explained well enough, please tell me. ;)