java 如何从 JTextField 获取输入，然后将其存储在变量中？
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How Do I Get Input From A JTextField, Then Store It In A Variable?
提问by Mrunited12
I've setup a JTextField, for users to input the base of the triange (It's a triangle area calculator) and I need to know how to store their input into a variable.
我已经设置了一个 JTextField，供用户输入三角形的底数（它是一个三角形面积计算器），我需要知道如何将他们的输入存储到一个变量中。
I tried an action listener but it game an error.
我尝试了一个动作监听器，但它游戏出错了。
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Scanner;
import javax.swing.*;
public class Triangle extends JFrame implements ActionListener{
static Scanner sc = new Scanner(System.in);
public static void findingTriangle(){
JFrame jf = new JFrame();
JTextField textfield = new JTextField("", 30);
JPanel panel = new JPanel();
JLabel jl = new JLabel("Triangle Area Calculator");
jf.setSize(500, 500);
jf.setVisible(true);
jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jf.add(panel);
panel.add(jl);
panel.add(textfield);
}
public static void main(String[] args){
findingTriangle();
}
@Override
public void actionPerformed(ActionEvent arg0) {
// TODO Auto-generated method stub
}
}
回答by Jens
Define a button and add the actionListener.
定义一个按钮并添加 actionListener。
Define textfield and your variable as static fields and assign textarea.getText()to your variable:
将文本字段和您的变量定义为静态字段并分配textarea.getText()给您的变量：
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Scanner;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class Triangle extends JFrame implements ActionListener {
static Scanner sc = new Scanner(System.in);
static String s;
static JTextField textfield;
static JButton jButton;
public static void findingTriangle() {
JFrame jf = new JFrame();
textfield = new JTextField("", 30);
jButton = new JButton("Click");
jButton.addActionListener(new Triangle());
JPanel panel = new JPanel();
JLabel jl = new JLabel("Triangle Area Calculator");
jf.setSize(500, 500);
jf.setVisible(true);
jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jf.add(panel);
panel.add(jl);
panel.add(textfield);
panel.add(jButton);
}
public static void main(String[] args) {
findingTriangle();
}
@Override
public void actionPerformed(ActionEvent arg0) {
s = textfield.getText();
}
}
回答by MadProgrammer
You can attach an ActionListenerto the JTextFieldwhich, when the user presses the Enterbutton, will trigger the actionPerfomedmethod.
您可以将 附加ActionListener到JTextField，当用户按下Enter按钮时，将触发该actionPerfomed方法。
textfield.addActionListener(this);
From there, you can extract the value entered by the user using JTextField#getText.
从那里，您可以使用 提取用户输入的值JTextField#getText。
String value = textField.getText();
You could also add JButtonto the UI and attach the same ActionListenerto it, as it would give a better visual cue to the user
您还可以添加JButton到 UI 并将相同的内容附加ActionListener到它，因为它会给用户提供更好的视觉提示
I would also suggest you use a JSpinneror JFormattedTextFieldinstead, as they have functionality to validate the data automatically.
我还建议您使用 a JSpinnerorJFormattedTextField代替，因为它们具有自动验证数据的功能。
Have a look at How to Use Text Fields, How to Use Formatted Text Fields, How to Use Spinnersand How to Write an Action Listenersfor more details
查看如何使用文本字段、如何使用格式化文本字段、如何使用微调器和如何编写动作侦听器以获取更多详细信息
