Java Swing | JPasswordField

14 Apr, 2021
PasswordField is a part of javax.swing package . The class JPasswordField is a component that allows editing of a single line of text where the view indicates that something was typed by does not show the actual characters. JPasswordField inherits the JTextField class in javax.swing package.Constructors of the class are :  
JPasswordField(): constructor that creates a new PasswordField JPasswordField(int columns) : constructor that creates a new empty PasswordField with specified number of columns. JPasswordField(String Password) : constructor that creates a new empty Password field initialized with the given string. JPasswordField(String Password, int columns) : constructor that creates a new empty PasswordField with the given string and a specified number of columns . JPasswordField(Document doc, String Password, int columns) : constructor that creates a Passwordfield that uses the given text storage model and the given number of columns.  
JPasswordField(): constructor that creates a new PasswordField 
JPasswordField(int columns) : constructor that creates a new empty PasswordField with specified number of columns. 
JPasswordField(String Password) : constructor that creates a new empty Password field initialized with the given string. 
JPasswordField(String Password, int columns) : constructor that creates a new empty PasswordField with the given string and a specified number of columns . 
JPasswordField(Document doc, String Password, int columns) : constructor that creates a Passwordfield that uses the given text storage model and the given number of columns.  
Commonly used method of JPasswordField :  
char getEchoChar() : returns the character used for echoing in JPasswordField. setEchoChar(char c) : set the echo character for JPasswordField. String getPassword() : returns the text contained in JPasswordField. String getText() : returns the text contained in JPasswordField. 
char getEchoChar() : returns the character used for echoing in JPasswordField. 
setEchoChar(char c) : set the echo character for JPasswordField. 
String getPassword() : returns the text contained in JPasswordField. 
String getText() : returns the text contained in JPasswordField. 
1. Program to enter name and password using JTextField and JPasswordField  
Java
// Java Program to enter name and password// using JTextField and JPasswordFieldimport java.awt.event.*;import java.awt.*;import javax.swing.*;class text extends JFrame implements ActionListener {    // JTextField    static JTextField t;     // JPasswordField    static JPasswordField pass;     // JFrame    static JFrame f;     // JButton    static JButton b;     // label to display text    static JLabel l;     // default constructor    text()    {    }     // main class    public static void main(String[] args)    {        // create a new frame to store text field and button        f = new JFrame("textfield");         // create a label to display text        l = new JLabel("nothing entered");         // create a new button        b = new JButton("submit");         // create a object of the text class        text te = new text();         // addActionListener to button        b.addActionListener(te);         // create a object of JTextField with 16 columns and initial text        t = new JTextField("enter name", 16);         // create a object of passwordField with 16 columns        pass = new JPasswordField(16);         // create an object of font type        Font fo = new Font("Serif", Font.ITALIC, 20);         // set the font of the textfield        t.setFont(fo);         // create a panel to add buttons and textfield        JPanel p = new JPanel();         // add buttons and textfield to panel        p.add(t);        p.add(pass);        p.add(b);        p.add(l);         // add panel to frame        f.add(p);         // set the size of frame        f.setSize(300, 300);         f.show();    }     // if the button is pressed    public void actionPerformed(ActionEvent e)    {        String s = e.getActionCommand();        if (s.equals("submit")) {            // set the text of the label to the text of the field            l.setText("name = " + t.getText() + "\t Password = " + pass.getText());             // set the text of field to blank            t.setText("  ");             // set the text of password field to blank            pass.setText("");        }    }}
output :  
2. Program to change the echo character of JPasswordField and set initial text for password field  
Java
// Java Program to change the echo character of// JPasswordField and set initial text for password fieldimport java.awt.event.*;import java.awt.*;import javax.swing.*;class text extends JFrame implements ActionListener, FocusListener {    // JTextField    static JTextField t;     // JPasswordField    static JPasswordField pass;     // JFrame    static JFrame f;     // JButton    static JButton b;     // label to display text    static JLabel l;     // default constructor    text()    {    }     // main class    public static void main(String[] args)    {        // create a new frame to store text field and button        f = new JFrame("textfield");         // create a label to display text        l = new JLabel("nothing entered");         // create a new button        b = new JButton("submit");         // create a object of the text class        text te = new text();         // addActionListener to button        b.addActionListener(te);         // create a object of JTextField with 16 columns and initial text        t = new JTextField("enter name", 16);         // create a object of passwordField with 16 columns        pass = new JPasswordField(16);         // add FocusListener to passwordField        pass.addFocusListener(te);         // set the echo character of the password field        pass.setEchoChar((char)0);         // set initial text for password field        pass.setText("enter password");         // set the echo character of the password field        // create an object of font type        Font fo = new Font("Serif", Font.ITALIC, 20);         // set the font of the textfield        t.setFont(fo);         // create a panel to add buttons and textfield        JPanel p = new JPanel();         // add buttons and textfield to panel        p.add(t);        p.add(pass);        p.add(b);        p.add(l);         // add panel to frame        f.add(p);         // set the size of frame        f.setSize(300, 300);         f.show();    }    // flag to set the text to blank for the first time when the component gets focus    boolean flag = true;     // events of focus listener    // when focus is gained    public void focusGained(FocusEvent e)    {        if (flag) {            // set a definite echo char            pass.setEchoChar('*');             // only set the text to blank for 1st time            // set the text to blank            pass.setText("");            flag = false;        }    }     // when the focus is lost    public void focusLost(FocusEvent e)    {    }     // if the button is pressed    public void actionPerformed(ActionEvent e)    {        String s = e.getActionCommand();        if (s.equals("submit")) {            // set the text of the label to the text of the field            l.setText("name = " + t.getText() + "\t, Password = " + pass.getText());             // set the text of field to blank            t.setText("  ");             // set the text of password field to blank            pass.setText("");        }    }}
Note : The above programs might not run in an online compiler use an offline IDE. the default text and number of columns of password can be changed by the programmer as per their need. 
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