OOP原则:组合大于继承!
//继承
class A expends B{
}
//组合
class A{
public B b;
}
简易计算器的实现:
目录
实现结果:
1. 程序代码(简单粗暴版):面向过程的写法
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
//简易计算器
public class TestCalc {
public static void main(String[] args) {
new Calculator();
}
}
//计算器类
class Calculator extends Frame{
public Calculator(){
//3个文本框
TextField field1 = new TextField(10);
TextField field2= new TextField(10);
TextField field3 = new TextField(20); //最大容纳字符数
//1个按钮
Button button = new Button("=");
button.addActionListener(new MyCalculatorListener(field1,field2,field3));
//1个标签
Label label = new Label("+");
//布局
setLayout(new FlowLayout());
add(field1);
add(label);
add(field2);
add(button);
add(field3);
setVisible(true);
pack();
}
}
//监听器类
class MyCalculatorListener implements ActionListener{
//获取三个变量
private TextField field1,field2,field3;
public MyCalculatorListener(TextField field1,TextField field2,TextField field3){
this.field1= field1;
this.field2= field2;
this.field3= field3;
}
@Override
public void actionPerformed(ActionEvent e){
//1.获得加数和被加数
int n1 = Integer.parseInt(field1.getText());
int n2 = Integer.parseInt(field2.getText());
//2.将+法运算后,放进第三个框中
field3.setText(""+(n1+n2));
//3.清除前两个框中的内容
field1.setText("");
field2.setText("");
}
}
2. 程序代码(进阶版):完全改造为面向对象的写法
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
//简易计算器
public class TestCalc {
public static void main(String[] args) {
new Calculator().loadFrame();
}
}
//计算器类
class Calculator extends Frame{
TextField num1,num2,num3;
public void loadFrame(){
num1 = new TextField(10);
num2 = new TextField(10);
num3 = new TextField(20);//最大容纳字符数
Button button = new Button("=");
Label label = new Label("+");
button.addActionListener(new MyCalculatorListener(this));
//布局
setLayout(new FlowLayout());
add(num1);
add(label);
add(num2);
add(button);
add(num3);
pack();
setVisible(true);
}
}
//监听器类
class MyCalculatorListener implements ActionListener{
//获取计算器这个对象,在一个类中组合另外一个类
Calculator calculator = null;
public MyCalculatorListener(Calculator calculator){
this.calculator = calculator;
}
@Override
public void actionPerformed(ActionEvent e){
//1.获得加数和被加数
int n1 = Integer.parseInt(calculator.num1.getText());
int n2 = Integer.parseInt(calculator.num2.getText());
calculator.num3.setText(""+(n1+n2));//2.将+法运算后,放进第三个框中
//3.清除前两个框中的内容
calculator.num1.setText("");
calculator.num2.setText("");
}
}
3.程序代码(精修版):内部类
内部类:可以畅通无阻的访问外部类。
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
//简易计算器
public class TestCalc {
public static void main(String[] args) {
new Calculator().loadFrame();
}
}
//计算器类
class Calculator extends Frame{
TextField num1,num2,num3;
public void loadFrame(){
num1 = new TextField(10);
num2 = new TextField(10);
num3 = new TextField(20);//最大容纳字符数
Button button = new Button("=");
Label label = new Label("+");
button.addActionListener(new MyCalculatorListener());
//布局
setLayout(new FlowLayout());
add(num1);
add(label);
add(num2);
add(button);
add(num3);
pack();
setVisible(true);
}
//监听器类
private class MyCalculatorListener implements ActionListener{
@Override
public void actionPerformed(ActionEvent e){
//1.获得加数和被加数
int n1 = Integer.parseInt(num1.getText());
int n2 = Integer.parseInt(num2.getText());
num3.setText(""+(n1+n2));//2.将+法运算后,放进第三个框中
//3.清除前两个框中的内容
num1.setText("");
num2.setText("");
}
}
}
简单粗暴!
感谢ლ(°◕‵ƹ′◕ლ)!!!