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实现目标

如上，实现一个这样的计算器的功能

代码结构

全部代码

一个Main类

package ComputerTest;

import java.util.LinkedList;

import javafx.application.Application;
import javafx.event.Event;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.TextField;
import javafx.scene.image.Image;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.AnchorPane;
import javafx.scene.layout.GridPane;
import javafx.scene.text.Font;
import javafx.stage.Stage;

public class Main extends Application {
	private String logic;//存运算符的变量 null
	private TextField view;
	private String out="";
	public void start(Stage primaryStage) {
		try {
			AnchorPane root = new AnchorPane();
			Scene scene = new Scene(root);
			primaryStage.setScene(scene);
			primaryStage.setWidth(300);
			primaryStage.setHeight(420);
			primaryStage.setResizable(false);
			addComp(root);
			primaryStage.getIcons().add(new Image("ComputerTest/computer.png", 256, 256, true, true));
		        primaryStage.setTitle("Calculator");
			primaryStage.show();
		} catch(Exception e) {
			e.printStackTrace();
		}
	}
	
	//添加组件的方法
	private void addComp(AnchorPane root) {
		//添加显示框
		view = new TextField("0");
		view.setMinSize(280, 50);
		view.setLayoutX(10);
		view.setLayoutY(15);
		//设置只读
		view.setEditable(false);
		//内容右对齐
		view.setAlignment(Pos.CENTER_RIGHT);
		//设置字体
		view.setFont(new Font("华文琥珀", 20));
		root.getChildren().add(view);
		
		//添加一个表格布局
		GridPane gridPane = new GridPane();
		//设置布局中元素组件横向间距
		gridPane.setHgap(1);
		//设置布局中元素组件纵向间距
		gridPane.setVgap(1);
		gridPane.setLayoutY(65);
		gridPane.setPrefWidth(290);
		gridPane.setPrefHeight(300);
		gridPane.setPadding(new Insets(10));
		//列容器
		root.getChildren().add(gridPane);
		
		//创建数字监听器对象
		NumberEvent numberEvent = new NumberEvent();
		//添加按钮
		Button btn_7 = new MyButton("7");
		btn_7.setOnMouseClicked(numberEvent);
		gridPane.add(btn_7,0,1);
		
		Button btn_8 = new MyButton("8");
		btn_8.setOnMouseClicked(numberEvent);
		gridPane.add(btn_8,1,1);
		
		Button btn_9 = new MyButton("9");
		btn_9.setOnMouseClicked(numberEvent);
		gridPane.add(btn_9,2,1);
		
		Button btn_4 = new MyButton("4");
		btn_4.setOnMouseClicked(numberEvent);
		gridPane.add(btn_4,0,2);
		
		Button btn_5 = new MyButton("5");
		btn_5.setOnMouseClicked(numberEvent);
		gridPane.add(btn_5,1,2);
		
		Button btn_6 = new MyButton("6");
		btn_6.setOnMouseClicked(numberEvent);
		gridPane.add(btn_6,2,2);
		
		Button btn_1 = new MyButton("1");
		btn_1.setOnMouseClicked(numberEvent);
		gridPane.add(btn_1,0,3);
		
		Button btn_2 = new MyButton("2");
		btn_2.setOnMouseClicked(numberEvent);
		gridPane.add(btn_2,1,3);
		
		Button btn_3 = new MyButton("3");
		btn_3.setOnMouseClicked(numberEvent);
		gridPane.add(btn_3,2,3);
		Button btn_0 = new MyButton("0");
		btn_0.setOnMouseClicked(numberEvent);
		gridPane.add(btn_0,0,4,2,1);
		
		Button btn_C = new MyButton("C");//鼠标点击到置零的操作
		btn_C.setOnMouseClicked(new EventHandler<Event>() {
			public void handle(Event event) {
				out="";
				view.setText("0");
			}
		});
		gridPane.add(btn_C,0,0,2,1);
		
		Button btn_eq = new MyButton("=");
		btn_eq.setStyle("-fx-background-color: blue");
		btn_eq.setOnMouseClicked(new EventHandler<Event>() {
			public void handle(Event event) {
				dispose();
			}
		});
		gridPane.add(btn_eq,3,4);
		
		//创建监听器对象
		LogicEvent logicEvent = new LogicEvent();
		Button btn_add = new MyButton("+");
		btn_add.setStyle("-fx-background-color: blue");
		btn_add.setOnMouseClicked(logicEvent);
		gridPane.add(btn_add,3,3);
		
		Button btn_sub = new MyButton("-");
		btn_sub.setStyle("-fx-background-color: blue");
		btn_sub.setOnMouseClicked(logicEvent);
		gridPane.add(btn_sub,3,2);
		
		Button btn_mul = new MyButton("x");
		btn_mul.setStyle("-fx-background-color: blue");
		btn_mul.setOnMouseClicked(logicEvent);
		gridPane.add(btn_mul,3,1);
		
		Button btn_div = new MyButton("/");
		btn_div.setStyle("-fx-background-color: blue");
		btn_div.setOnMouseClicked(logicEvent);
		gridPane.add(btn_div,3,0);
		
		Button btn_Point=new MyButton(".");
		btn_Point.setOnMouseClicked(logicEvent);
		gridPane.add(btn_Point, 2,4);
		
		
		Button btn_X=new MyButton("<=]");
		btn_X.setOnMouseClicked(new EventHandler<MouseEvent>() {
            @Override
            public void handle(MouseEvent event) {
            	if(out.length()>0){
            		out=""+out.substring(0,out.length()-1); 
            	}
                view.setText(out);
            }
        });
		btn_X.setFont(new Font("华文琥珀",20));//重写
		gridPane.add(btn_X, 2,0);
		
	}
	
	//数字监听器
	class NumberEvent implements EventHandler<Event>{
		public void handle(Event event) {
			//获取事件源  (获取触发事件的按钮)
			MyButton btn = (MyButton)event.getSource();
			//先获取当前按钮的内容
			String btnNumber = btn.getText();
			out+=btnNumber;
			view.setText(out);
		}
	}
	 //运算符的事件监听器
	class LogicEvent implements EventHandler<Event>{
		public void handle(Event event) {
			//得到按钮
			MyButton logicBtn = (MyButton)event.getSource();
			//获取按钮内容
			logic = logicBtn.getText();
			out+=logic;
			view.setText(out);
		}
		
	}
	
	//对文本框中的东西进行处理
	private void dispose(){
		LinkedList<String> list=new LinkedList<>();
		int t=0;
		for (int i = 0; i < out.length(); i++) {
			char c=out.charAt(i);
			if (c=='+'||c=='-'||c=='x'||c=='/') {
				String temp=out.substring(t,i); 
				list.add(temp);
				list.add(out.substring(i,i+1));
				t=i+1;
			}
		}
		list.add(out.substring(t,out.length()));
		//先处理掉所有的乘除运算
		while(true){
			t=list.size();
			for (int i = 0; i < list.size(); i++) {
				String st=list.get(i);
				if (st.equals("x")||st.equals("/")) {
					double temp=Double.parseDouble(list.get(i-1));
					if (st.equals("x")) {
						temp*=Double.parseDouble(list.get(i+1));
					}else {
						temp/=Double.parseDouble(list.get(i+1));
					}
					String string=""+temp;
					list.set(i-1, string);
					list.remove(i);
					list.remove(i);
				}
			}
			if (t==list.size()) {//如果集合的长度已经不发生改变了
				break;//则说明找完了
			}
		}
		
		//最后 处理加减运算
		while(list.size()!=1){
			int i=0;
			for (i = 0; i < list.size(); i++) {
				String st=list.get(i);
				if (st.equals("+")||st.equals("-")) {
					double temp=Double.parseDouble(list.get(i-1));
					if (st.equals("+")) {
						temp+=Double.parseDouble(list.get(i+1));
					}else {
						temp-=Double.parseDouble(list.get(i+1));
					}
					String string=""+temp;
					list.set(i-1, string);
					list.remove(i);
					list.remove(i);
					i=0;//特别注意加减是要按照顺序算的！！！一个坑
					//没有这个，就会出现1-2-3-4的计算（1-2）-（3-4）的效果！！
				}
			}
		}
		view.setText(list.get(0));
	}
	public static void main(String[] args) {
		launch(args);
	}
}

一个MyButton类

package ComputerTest;

import javafx.scene.control.Button;
import javafx.scene.text.Font;

public class MyButton extends Button{
	public MyButton(String text) {
		super(text);
		setPrefWidth(160);
		setPrefHeight(150);
		setFont(new Font("华文琥珀",30));
	}
}

测试效果

计算结果

核心算法（用于测试的）

package Test1;

import java.util.LinkedList;

public class test {
	public static void main(String[] args) {
		String out="1.2x2+5-45-7.2/3";
		LinkedList<String> list=new LinkedList<>();
		int t=0;
		for (int i = 0; i < out.length(); i++) {
			char c=out.charAt(i);
			if (c=='+'||c=='-'||c=='x'||c=='/') {
				String temp=out.substring(t,i); 
				list.add(temp);
				list.add(out.substring(i,i+1));
				t=i+1;
			}
		}
		list.add(out.substring(t,out.length()));
		System.out.println(list);
		//先处理掉所有的乘除运算
		while(true){
			t=list.size();
			for (int i = 0; i < list.size(); i++) {
				String st=list.get(i);
				if (st.equals("x")||st.equals("/")) {
					double temp=Double.parseDouble(list.get(i-1));
					if (st.equals("x")) {
						temp*=Double.parseDouble(list.get(i+1));
					}else {
						temp/=Double.parseDouble(list.get(i+1));
					}
					String string=""+temp;
					list.set(i-1, string);
					list.remove(i);
					list.remove(i);
				}
			}
			if (t==list.size()) {//如果集合的长度已经不发生改变了
				break;//则说明找完了
			}
		}
		
		System.out.println(list);
		//最后 处理加减运算
		while(list.size()!=1){
			int i=0;
			for (i = 0; i < list.size(); i++) {
				String st=list.get(i);
				if (st.equals("+")||st.equals("-")) {
					double temp=Double.parseDouble(list.get(i-1));
					if (st.equals("+")) {
						temp+=Double.parseDouble(list.get(i+1));
					}else {
						temp-=Double.parseDouble(list.get(i+1));
					}
					String string=""+temp;
					list.set(i-1, string);
					list.remove(i);
					list.remove(i);
					i=0;//特别注意加减是要按照顺序算的！！！一个坑
					//没有这个，就会出现1-2-3-4的计算（1-2）-（3-4）的效果！！
				}
			}
		}
		System.out.println(list);
	}
}

这个核心算法主要是对我们计算器输入的字符串进行处理，上面的out是可以自定义的，在计算器的代码的实现中，dispose函数的作用就是把这个算法的放进去的，测试的时候，推荐更改不同的out的值，进行测试，出现问题了，推荐加上一些输出语句看效果，当然，会debug的，用debug更好了。
上面把这个test的测试的代码的结果截图来看一看。

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