好的,所以我正在尝试根据我用来学习 Java 的书做一个练习。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();
}
}
这里是精确措辞的练习:
Modify the class Calculator.java to keep all numeric buttons in the 10-element array declared as follows:
Buttons[] numButtons= new Buttons[10];
Replace 10 lines that start from
button0=new JButton("0");
with a loop that creates the buttons and store them in this array.
好的,所以我尝试用 Buttons[] numbuttons 行声明数组
,但这只是给我错误:
Multiple markers at this line
-Buttons can not be resolved to a type
-Buttons can not be resolved to a type
我改为尝试这个:
JButton[] buttons = new JButton[10]
然后像这样将每个按钮添加到数组中:
buttons[0] = "button0";
当我声明数组时这样做并没有给我一个错误,但是当我写 buttons[0]
行时,我得到了这个错误:
Syntax error on token "buttons",delete this token
所以,我需要帮助弄清楚如何做到这一点。此外,这本书可以在这里找到:http://myflex.org/books/java4kids/JavaKid811.pdf练习在第 73 页。 如果我列出了太多信息,我深表歉意。这只是因为我对 Java 很陌生,我不确定什么是必要的。感谢帮助。谢谢。
最佳答案
您正在做的是在需要 JButton 时尝试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:
我刚刚做了这个
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());
}
}
得到了
0
用于输出,因此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();
}
}
关于java - 包含 JButton 对象的数组,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/9814566/