如何调用一个字符串出现在另一个类中 [英] How to call a string to appear in another class

问题描述

我有一个叫做Main的课程. Java的在这种情况下，输出由inputLine显示，它是从com端口串行获取的字符串.我希望此字符串值可用于同一默认包中的其他某个类.我如何在其他课堂上称呼这个字符串.如何创建此类的实例并在任何其他xyz.java类中调用字符串inputLine.一个例子将非常有帮助.

I have this class called Main. java. In this the output is shown by inputLine which is a string taken serially from the com port. i want this string value to be used in some other class which is in the same default package. How do i call this string in other class. How do i create an instance of this class and call the string inputLine in any other xyz.java class. An example would be very helpful.

    import java.io.BufferedReader;
    import java.io.InputStreamReader;
    import java.io.OutputStream;
    import gnu.io.CommPortIdentifier;
    import gnu.io.SerialPort;
    import gnu.io.SerialPortEvent;
    import gnu.io.SerialPortEventListener;
    import java.util.Enumeration;


public class Main implements SerialPortEventListener
{
    SerialPort serialPort;
        /** The port we're normally going to use. */
    private static final String PORT_NAMES[] = {
            "COM30", // Windows
    };
    /**
    * A BufferedReader which will be fed by a InputStreamReader
    * converting the bytes into characters
    * making the displayed results codepage independent
    */
    private BufferedReader input;
    /** The output stream to the port */
    private OutputStream output;
    /** Milliseconds to block while waiting for port open */
    private static final int TIME_OUT = 2000;
    /** Default bits per second for COM port. */
    private static final int DATA_RATE = 9600;

    public void initialize() {
        CommPortIdentifier portId = null;
        Enumeration portEnum = CommPortIdentifier.getPortIdentifiers();

        //First, Find an instance of serial port as set in PORT_NAMES.
        while (portEnum.hasMoreElements()) {
            CommPortIdentifier currPortId = (CommPortIdentifier) portEnum.nextElement();
            for (String portName : PORT_NAMES) {
                if (currPortId.getName().equals(portName)) {
                    portId = currPortId;
                    break;
                }
            }
        }
        if (portId == null) {
            System.out.println("Could not find COM port.");
            return;
        }

        try {
            // open serial port, and use class name for the appName.
            serialPort = (SerialPort) portId.open(this.getClass().getName(),
                    TIME_OUT);

            // set port parameters
            serialPort.setSerialPortParams(DATA_RATE,
                    SerialPort.DATABITS_8,
                    SerialPort.STOPBITS_1,
                    SerialPort.PARITY_NONE);

            // open the streams
            input = new BufferedReader(new InputStreamReader(serialPort.getInputStream()));
            output = serialPort.getOutputStream();

            // add event listeners
            serialPort.addEventListener(this);
            serialPort.notifyOnDataAvailable(true);
        } catch (Exception e) {
            System.err.println(e.toString());
        }
    }

    /**
     * This should be called when you stop using the port.
     * This will prevent port locking on platforms like Linux.
     */
    public synchronized void close() {
        if (serialPort != null) {
            serialPort.removeEventListener();
            serialPort.close();
        }
    }

    /**
     * Handle an event on the serial port. Read the data and print it.
     */
    public synchronized void serialEvent(SerialPortEvent oEvent) {
        if (oEvent.getEventType() == SerialPortEvent.DATA_AVAILABLE) {
            try {
                String inputLine=input.readLine();
                System.out.println(inputLine);

            } catch (Exception e) {
                System.err.println(e.toString());
            }
        }
        // Ignore all the other eventTypes, but you should consider the other ones.
    }

    public static void main(String[] args) throws Exception {
        Main main = new Main();
        main.initialize();
        Thread t=new Thread() {
            public void run() {
                //the following line will keep this app alive for 1000 seconds,
                //waiting for events to occur and responding to them (printing incoming messages to console).
                try {Thread.sleep(1000000);} catch (InterruptedException ie) {}
            }
        };
        t.start();
        System.out.println("Started");
    }
}

推荐答案

在您的情况下，您应该只创建一个类变量. 只需在类public static String inputLine;中声明 更改字符串inputLine = input.readLine();到inputLine=input.readLine();，您可以使用Main.inputLine从同一包中的其他类访问它.

In your case, you should just create a class variable. Just declare inside the class, public static String inputLine; Change String inputLine=input.readLine(); to inputLine=input.readLine(); and you can access it from other classes in the same package using Main.inputLine.

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