user61539: I want to display float values in JTextArea but it doesn't show any. It only displays on the systemout. Pls help me out. This is my Java code.
import jssc.SerialPort;
import jssc.SerialPortException;

    public ards() {
        initComponents();
    }

    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jLabel1 = new javax.swing.JLabel();
        jPanel1 = new javax.swing.JPanel();
        jButton1 = new javax.swing.JButton();
        jLabel2 = new javax.swing.JLabel();
        jScrollPane1 = new javax.swing.JScrollPane();
        jTextArea1 = new javax.swing.JTextArea();

        jLabel1.setText("jLabel1");

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jButton1.setText("jButton1");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        jTextArea1.setEditable(false);
        jTextArea1.setColumns(20);
        jTextArea1.setRows(5);
        jScrollPane1.setViewportView(jTextArea1);

        javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(jPanel1Layout.createSequentialGroup()
                        .addGap(319, 319, 319)
                        .addComponent(jButton1))
                    .addGroup(jPanel1Layout.createSequentialGroup()
                        .addGap(154, 154, 154)
                        .addComponent(jLabel2, javax.swing.GroupLayout.PREFERRED_SIZE, 110, javax.swing.GroupLayout.PREFERRED_SIZE))
                    .addGroup(jPanel1Layout.createSequentialGroup()
                        .addGap(140, 140, 140)
                        .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)))
                .addContainerGap(157, Short.MAX_VALUE))
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addGap(74, 74, 74)
                .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(18, 18, 18)
                .addComponent(jButton1)
                .addGap(18, 18, 18)
                .addComponent(jLabel2, javax.swing.GroupLayout.PREFERRED_SIZE, 36, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(94, Short.MAX_VALUE))
        );

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );

        pack();
    }// </editor-fold>                        

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
         String str;

        //In the constructor pass the name of the port with which we work
        SerialPort serialPort = new SerialPort("COM6");

        try {
            //Open port
            serialPort.openPort();

            //We expose the settings. You can also use this line - serialPort.setParams(9600, 8, 1, 0);
            serialPort.setParams(SerialPort.BAUDRATE_9600,
                    SerialPort.DATABITS_8,
                    SerialPort.STOPBITS_1,
                    SerialPort.PARITY_NONE);



            Thread.sleep(1000);//Very important !!!



            //Read data from port
            for (int i = 0; i < 1000; i++) {
                str = serialPort.readString();

                if (str != null) {
                    System.out.println(str);
                   jTextArea1.setText(str);
                    jLabel2.setText(str);
                }

                Thread.sleep(500);
            }

            //Closing the port
            serialPort.closePort();

        } catch (SerialPortException ex) {
            System.out.println(ex);
        } catch (InterruptedException ex) {
            System.out.println(ex);
        }
    }                                        

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(ards.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(ards.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(ards.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(ards.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new ards().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify                     
    private javax.swing.JButton jButton1;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JTextArea jTextArea1;
    // End of variables declaration                   
}

And this is my Arduino code
const int model = 0;   
void setup() {
Serial.begin(9600);
}

float sensitivity[] ={
0.185, // for ACS712ELCTR-05B-T
0.100, // for ACS712ELCTR-20A-T
0.066 // for ACS712ELCTR-30A-T } ;

void loop() {  
static unsigned long count=0;
static float Vsum=0;
float Vave=0;
int volt = analogRead(A1);
float voltage= map(volt,0,1023, 0, 2500)/100.0;
Vsum=Vsum+voltage;

static float Csum=0;
float Cave=0;
 float milli = pow(10, -3);
 float current = (voltage / sensitivity[model]);
 float current1 = current*milli;
Csum=Csum+current1;
count++;
Vave=Vsum/count;
Cave=Csum/count;


Serial.print("Average voltage: ");
Serial.print(Vave,2);
Serial.println("V");
Serial.print("Average current: ");
Serial.print(Cave,3);
Serial.println("A");
Serial.println("-----");
delay(3000);

}


user39456: In you code : str = serialPort.readString();
Change this as ->   str = serialPort.readStringUntil('\n');  

61539: <p>I want to display float values in JTextArea but it doesn't show any. It only displays on the systemout. Pls help me out. This is my Java code.</p>

<pre><code>import jssc.SerialPort;
import jssc.SerialPortException;

    public ards() {
        initComponents();
    }

    @SuppressWarnings("unchecked")
    // &lt;editor-fold defaultstate="collapsed" desc="Generated Code"&gt;                          
    private void initComponents() {

        jLabel1 = new javax.swing.JLabel();
        jPanel1 = new javax.swing.JPanel();
        jButton1 = new javax.swing.JButton();
        jLabel2 = new javax.swing.JLabel();
        jScrollPane1 = new javax.swing.JScrollPane();
        jTextArea1 = new javax.swing.JTextArea();

        jLabel1.setText("jLabel1");

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jButton1.setText("jButton1");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        jTextArea1.setEditable(false);
        jTextArea1.setColumns(20);
        jTextArea1.setRows(5);
        jScrollPane1.setViewportView(jTextArea1);

        javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(jPanel1Layout.createSequentialGroup()
                        .addGap(319, 319, 319)
                        .addComponent(jButton1))
                    .addGroup(jPanel1Layout.createSequentialGroup()
                        .addGap(154, 154, 154)
                        .addComponent(jLabel2, javax.swing.GroupLayout.PREFERRED_SIZE, 110, javax.swing.GroupLayout.PREFERRED_SIZE))
                    .addGroup(jPanel1Layout.createSequentialGroup()
                        .addGap(140, 140, 140)
                        .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)))
                .addContainerGap(157, Short.MAX_VALUE))
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addGap(74, 74, 74)
                .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(18, 18, 18)
                .addComponent(jButton1)
                .addGap(18, 18, 18)
                .addComponent(jLabel2, javax.swing.GroupLayout.PREFERRED_SIZE, 36, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(94, Short.MAX_VALUE))
        );

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );

        pack();
    }// &lt;/editor-fold&gt;                        

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
         String str;

        //In the constructor pass the name of the port with which we work
        SerialPort serialPort = new SerialPort("COM6");

        try {
            //Open port
            serialPort.openPort();

            //We expose the settings. You can also use this line - serialPort.setParams(9600, 8, 1, 0);
            serialPort.setParams(SerialPort.BAUDRATE_9600,
                    SerialPort.DATABITS_8,
                    SerialPort.STOPBITS_1,
                    SerialPort.PARITY_NONE);



            Thread.sleep(1000);//Very important !!!



            //Read data from port
            for (int i = 0; i &lt; 1000; i++) {
                str = serialPort.readString();

                if (str != null) {
                    System.out.println(str);
                   jTextArea1.setText(str);
                    jLabel2.setText(str);
                }

                Thread.sleep(500);
            }

            //Closing the port
            serialPort.closePort();

        } catch (SerialPortException ex) {
            System.out.println(ex);
        } catch (InterruptedException ex) {
            System.out.println(ex);
        }
    }                                        

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //&lt;editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) "&gt;
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(ards.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(ards.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(ards.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(ards.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //&lt;/editor-fold&gt;

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new ards().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify                     
    private javax.swing.JButton jButton1;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JTextArea jTextArea1;
    // End of variables declaration                   
}
</code></pre>

<p>And this is my Arduino code</p>

<pre><code>const int model = 0;   
void setup() {
Serial.begin(9600);
}

float sensitivity[] ={
0.185, // for ACS712ELCTR-05B-T
0.100, // for ACS712ELCTR-20A-T
0.066 // for ACS712ELCTR-30A-T } ;

void loop() {  
static unsigned long count=0;
static float Vsum=0;
float Vave=0;
int volt = analogRead(A1);
float voltage= map(volt,0,1023, 0, 2500)/100.0;
Vsum=Vsum+voltage;

static float Csum=0;
float Cave=0;
 float milli = pow(10, -3);
 float current = (voltage / sensitivity[model]);
 float current1 = current*milli;
Csum=Csum+current1;
count++;
Vave=Vsum/count;
Cave=Csum/count;


Serial.print("Average voltage: ");
Serial.print(Vave,2);
Serial.println("V");
Serial.print("Average current: ");
Serial.print(Cave,3);
Serial.println("A");
Serial.println("-----");
delay(3000);

}
</code></pre>
 39456: <p>In you code : str = serialPort.readString();</p>

<p>Change this as ->   str = serialPort.readStringUntil('\n');  </p>
