JPasswordField

JPasswordField allows you to edit a single of text. The original characters input are not displayed. You can specify the character to display instead of the original characters by using the setEchoChar(char ch) method.

Constructors of the JPasswordField class:
-JPasswordField()
creates a new password field.
-JPasswordField(int columns)
create a new pasword field with specified number of columns.
-JPasswordField(String text)
creates a new password field with the default password text.
-JPasswordField(String text, int columns)
create a new password field with the default password text and number of columns.
-JPasswordField(Document doc, String text, int columns)
create a new password field with the specified document model, the default password text and number of columns.

Useful methods of the JPasswordField class:
-getPassword():char[]
gets the text from the password field.
-setEchoChar(char ch):void
sets echo character of the password field. This character is shown in the password field instead of the original characters.

Example:

import java.awt.Color;
import java.awt.Container;
import java.awt.FlowLayout;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JPasswordField;
import javax.swing.JTextField;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.plaf.basic.BasicBorders;

class JPasswordFieldShow extends JFrame implements DocumentListener{
JTextField txtname;
JPasswordField txtpassword;
JLabel lbl;
JPasswordFieldShow(String title){
setTitle(title);
setSize(500,150);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Container contpane=getContentPane();
contpane.setLayout(new FlowLayout());
JPanel p1=new JPanel();
p1.setLayout(new BoxLayout(p1, BoxLayout.Y_AXIS));
JPanel p2=new JPanel();
p2.setLayout(new BoxLayout(p2, BoxLayout.Y_AXIS));
JLabel lblname=new JLabel("Name:");
txtname=new JTextField(20);
JLabel lblpassword=new JLabel("Password:");
txtpassword=new JPasswordField(20);
txtpassword.setEchoChar('*');
txtpassword.getDocument().addDocumentListener(this);
JButton btok=new JButton("OK");
btok.setBorder(new BasicBorders.ButtonBorder(Color.GREEN,Color.BLACK,Color.GREEN,Color.YELLOW));
lbl=new JLabel("  ");
lbl.setForeground(Color.RED);
lbl.setLabelFor(txtpassword);
p1.add(lblname);
p2.add(txtname);
p1.add(lblpassword);
p2.add(txtpassword);
p1.add(btok);
p2.add(lbl);
JPanel mp=new JPanel();
mp.setLayout(new BoxLayout(mp,BoxLayout.X_AXIS));
mp.add(p1);
mp.add(p2);
contpane.add(mp);
setVisible(true);

}
public void checkPassword(char[] passwordText){
boolean str=strongPass(passwordText);
if(str)
lbl.setText("Strong password");
else
lbl.setText("Weak weak");
}
public void removeUpdate(DocumentEvent e){
checkPassword(txtpassword.getPassword());
}
public void insertUpdate(DocumentEvent e){

checkPassword(txtpassword.getPassword());
}
public void changedUpdate(DocumentEvent e){


}

public boolean strongPass(char[] passwordText){
boolean strong=false;
if(passwordText.length>=8){
if(countDigit(passwordText)>0 && countLowercase(passwordText)>0 && countUppercase(passwordText)>0 && countSymbol(passwordText)>0)
strong=true;
}
return strong;
}
public int countDigit(char[] passwordText){
int digitNum=0;
for(char c:passwordText){
if(c>='0' && c<='9')
digitNum++;
}
return digitNum;
}

public int countLowercase(char[] passwordText){
int lowercaseNum=0;
for(char c:passwordText){
if(c>='a' && c<='z')
lowercaseNum++;
}
return lowercaseNum;
}
public int countUppercase(char[] passwordText){
int uppercaseNum=0;
for(char c:passwordText){
if(c>='A' && c<='Z')
uppercaseNum++;
}
return uppercaseNum;
}
public int countSymbol(char[] passwordText){
int symNum=0;
for(char c:passwordText){
if((c>='!' && c<='/') || (c>=':' && c<='@') || (c>='[' && c<='`') || (c>='{' && c<='~' ))
symNum++;
}
return symNum;
}
}

public class JFrameSwing {
public static void main(String[] args){
new JPasswordFieldShow("JPasswordField");
}
}