包含JButton对象的数组

Question

好的，所以我试图从我用来学习Java的书中进行练习。这是我到目前为止的代码：

import javax.swing.*;
import java.awt.GridLayout;
import java.awt.BorderLayout;
public class Calculator {
    //Declaration of all calculator's components.
    JPanel windowContent;
    JTextField displayField;
    JButton button0;
    JButton button1;
    JButton button2;
    JButton button3;
    JButton button4;
    JButton button5;
    JButton button6;
    JButton button7;
    JButton button8;
    JButton button9;
    JButton buttonPoint;
    JButton buttonAdd;
    JButton buttonEqual;
    JPanel pl;

    //Constructor creates the components in memory and adds the to the frame using combination of Borderlayout.
    Calculator() {
        windowContent= new JPanel();

    // Set the layout manager for this panel
        BorderLayout bl = new BorderLayout();
        windowContent.setLayout(bl);

    //Create the display field and place it in the North area of the window
        displayField = new JTextField(30);
        windowContent.add("North",displayField);

    //Create button field and place it in the North area of the window
        button0=new JButton("0");
        button1=new JButton("1");
        button2=new JButton("2");
        button3=new JButton("3");
        button4=new JButton("4");
        button5=new JButton("5");
        button6=new JButton("6");
        button7=new JButton("7");
        button8=new JButton("8");
        button9=new JButton("9");
        buttonAdd=new JButton("+");
        buttonPoint = new JButton(".");
        buttonEqual=new JButton("=");

    //Create the panel with the GridLayout that will contain 12 buttons - 10 numeric ones, and button with the points
    //and the equal sign.
        pl = new JPanel ();
        GridLayout gl =new GridLayout(4,3);
        pl.setLayout(gl);
    //Add window controls to the panel pl.
        pl.add(button1);
        pl.add(button2);
        pl.add(button3);
        pl.add(button4);
        pl.add(button5);
        pl.add(button6);
        pl.add(button7);
        pl.add(button8);
        pl.add(button9);
        pl.add(buttonAdd);
        pl.add(buttonPoint);
        pl.add(buttonEqual);

    //Add the panel pl to the center area of the window
        windowContent.add("Center",pl);
    //Create the frame and set its content pane
        JFrame frame = new JFrame("Calculator");
        frame.setContentPane(windowContent);
    //set the size of the window to be big enough to accomodate all controls.
        frame.pack();
    //Finnaly, display the window
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        Calculator calc = new Calculator();
    }
}

以下是确切措词的练习：

修改类Calculator.java，以将所有数字按钮保留在声明为10个元素的数组中，如下所示：

Buttons[] numButtons= new Buttons[10];

替换从10开始的行

button0=new JButton("0");

带有创建按钮并将其存储在此数组中的循环。

好的，所以我尝试使用声明数组Buttons[] numbuttons line，但这给了我错误：

这行有多个标记-
按钮无法解析为类型-
按钮无法解析为类型

相反，我尝试了这个：

JButton[] buttons = new JButton[10]

然后将每个按钮添加到数组中，如下所示：

buttons[0] = "button0";

声明数组时，这样做并没有给我一个错误，但是当我编写该buttons[0]行时，出现了此错误：

令牌“按钮”上的语法错误，请删除此令牌

因此，我需要帮助弄清楚如何执行此操作。另外，可以在以下位置找到该书：http
:
//myflex.org/books/java4kids/JavaKid811.pdf，该练习在第73页上。如果我列出的信息太多，我深表歉意。只是因为我对Java还是很陌生，所以我不确定什么是必要的。感谢帮助。谢谢。

Answer 1

您正在做的是尝试在需要JButton时将数组空间设置为字符串。

你应该这样做

buttons[0] = new JButton("0");

代替

buttons[0] = "button0";

编辑：

我只是这样做

import javax.swing.*;

public class test {

    public static void main(String[] args) {
        JButton[] buttons = new JButton[10];

        buttons[0] = new JButton("0");

        System.out.println(buttons[0].getText());
    }

}

并得到

0

为输出，以便您的错误不在该行中。

编辑：代码

计算器.java

import javax.swing.*;
import java.awt.GridLayout;
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class Calculator {
    //Declaration of all calculator's components.
    JPanel windowContent;
    JTextField displayField;
    JButton buttons[];
    JButton buttonPoint;
    JButton buttonAdd;
    JButton buttonEqual;
    JPanel pl;

    //Constructor creates the components in memory and adds the to the frame using combination of Borderlayout.
    Calculator() {
        windowContent= new JPanel();
        buttons = new JButton[10];

    // Set the layout manager for this panel
        BorderLayout bl = new BorderLayout();
        windowContent.setLayout(bl);

    //Create the display field and place it in the North area of the window
        displayField = new JTextField(30);
        windowContent.add("North",displayField);

    //Create button field and place it in the North area of the window
        for(int i = 0; i < 10; i++) {
            buttons[i] = new JButton(String.valueOf(i));
        }

        buttonAdd=new JButton("+");
        buttonPoint = new JButton(".");
        buttonEqual=new JButton("=");

    //Create the panel with the GridLayout that will contain 12 buttons - 10 numeric ones, and button with the points
    //and the equal sign.
        pl = new JPanel ();
        GridLayout gl =new GridLayout(4,3);
        pl.setLayout(gl);
    //Add window controls to the panel pl.

        for(int i = 0; i < 10; i++) {
            pl.add(buttons[i]);
        }
        pl.add(buttonAdd);
        pl.add(buttonPoint);
        pl.add(buttonEqual);

    //Add the panel pl to the center area of the window
        windowContent.add("Center",pl);
    //Create the frame and set its content pane
        JFrame frame = new JFrame("Calculator");
        frame.setContentPane(windowContent);
    //set the size of the window to be big enough to accomodate all controls.
        frame.pack();
    //Finnaly, display the window
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        Calculator calc = new Calculator();
    }
}