Using setBounds() method, we have increased the height and width of button.

import javax.swing.*;
import java.awt.*;
import java.io.*;
import java.awt.event.*;
import java.sql.*;
class IncreaseButtonSize extends JFrame
{
JButton b;
JLabel label;
final JTextField text;

IncreaseButtonSize(){
setLayout(null);
label = new JLabel("Name");
text = new JTextField(20);

b=new JButton("View");
label.setBounds(10,10,100,20);
text.setBounds(120,10,120,20);
b.setBounds(120,40,150,40);


add(label);
add(text);
add(b);
b.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae){
String value=text.getText();
JOptionPane.showMessageDialog(null,"Hello "+value);
}
});
}

public static void main(String arg[])
{

IncreaseButtonSize frame=new IncreaseButtonSize();
frame.setSize(300,120);
frame.setVisible(true);
}
}