Java Basic(52)-Event Handling

import java.awt.FlowLayout;

import java.awt.event.ActionListener;

import java.awt.event.ActionEvent;

import javax.swing.JFrame;

import javax.swing.JTextField;

import javax.swing.JPasswordField;

import javax.swing.JOptionPane;

public class tuna extends JFrame{

private JTextField item1;

private JTextField item2;

private JTextField item3;

private JPasswordField passwordField;

public tuna(){

super("The title");

setLayout(new FlowLayout());

item1 = new JTextField(10);

add(item1);

item2 = new JTextField("enter text here");

add(item2);

item3 = new JTextField("uneditable");

item3.setEditable(false);

add(item3);

passwordField = new JPasswordField("mypass");

add(passwordField);

}

}

Java Basic(51)-GUI with Jframe

import java.awt.FlowLayout;

import javax.swing.JFrame; → 滙入所需要的

import javax.swing.JLabel;

public class tuna extends JFrame{

private JLabel item1;

public tuna(){

super("The title Bar"); →標題

setLayout(new FlowLayout());

item1 = new JLabel("This is a sentences"); →文字在顯示框

item1.setToolTipText("This is gonna show up on hover");

add(item1);

}

}

import javax.swing.JFrame;

class apples{

public static void main(String[] args){

tuna bucky = new tuna();

bucky.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); → 按X関閉

bucky.setSize(275,180); →此顯示框的大小

bucky.setVisible(true); →顯示此顯示框

}

}

這是運行時的結果： 

Java Basic(50)-Graphical User Interface GUI

import javax.swing.JOptionPane; →滙入使用JOptionPane

class apples{

public static void main(String[] args){

String fn = JOptionPane.showInputDialog("Enter first number");

String sn = JOptionPane.showInputDialog("Enter second number");

int num1 = Integer.parseInt(fn); →改變字符串到整數

int num2 = Integer.parseInt(sn); →改變字符串到整數

int sum = num1 + num2;

JOptionPane.showMessageDialog(null, "The answer is " +sum, "the title", JOptionPane.PLAIN_MESSAGE);

}

}

這是運行時的結果：

Java Basic(49)-Inheritance繼承

In food.java:

public class food {

public void eat(){ →必須是public的，因為private不能使用

System.out.println("I am the eat methods");

}

}

In potpie.java and tuna.java:

public class tuna extends food{

public void eat(){

System.out.println("I am the new method of tuna"); →將覆寫方法

}

}

public class potpie extends food{ → extends的意思是繼承 food.java

}

In apple.java:

class apples{

public static void main(String[] args){

tuna tunaObject = new tuna();

potpie potObject = new potpie();

tunaObject.eat();

potObject.eat();

}

}

這是運行時的結果：

I am the new method of tuna

I am the eat methods

Java Basic(48)-Final

public class tuna {

private int sum;

private final int NUMBER; → final 價值不能改變它

public tuna(int x){

NUMBER = x;

}

public void add(){

sum+=NUMBER; → sum 可以改變，因為它不是 final

}

public String toString(){

return String.format("sum = %d\n", sum);

}

}

class apples{

public static void main(String[] args){

tuna tunaObject = new tuna(10); →NUMBER的值是10

for(int i=0; i<5; i++){

tunaObject.add(); -->調用add方法()

System.out.printf("%s",tunaObject);

}

}

}

這是運行時的結果：

sum = 10

sum = 20

sum = 30

sum = 40

sum = 50

Java Basic(47)-Static(2)

public class tuna {

private String first;

private String last;

private static int members = 0;

public tuna(String fn,String ln){

first = fn;

last = ln;

members++;

System.out.printf("Construtor for %s %s,members in the club: %d\n",first,last,members);

}

public String getFirst(){

return first;

}

public String getLast(){

return last;

}

public static int getMembers(){

return members;

}

}

class apples{

public static void main(String[] args){

tuna member1 = new tuna("Megan","Fox");

tuna member2 = new tuna("Natalie","Portman");

tuna member3 = new tuna("Taylor","Swift");

System.out.println(tuna.getMembers());

}

}

因為靜態方法是共享所有的對象

這是運行時的結果：

Construtor for Megan Fox,members in the club: 1

Construtor for Natalie Portman,members in the club: 2

Construtor for Taylor Swift,members in the club: 3