如何從JTextField中取值並將其移入Int變量

Question

我一直在嘗試創建一個JFrame程序，它需要兩個數字和一個 操作（在jcombobox中）來計算答案。我需要爲用戶輸入數字1和2，並將該值分配給可用於計算答案的int。 num1是int變量，num1field是文本字段的名稱。

num1field.addActionListener(
     new ActionListener(){ 
      public void actionPerformed(ActionEvent event){ 
       num1 = Integer.parseInt(num1field.getText()); 
       num1field.setText(num1); 
      } 
     } 
    ); 

是的，num1 int已經被聲明在類的頂部。我得到一個錯誤，它說setText。

感謝所有幫助:)

Answer 1

沒有方法JTextField#setText(int)，只能提供一個String

num1field.setText(String.valueOf(num1)); 

應工作

你可能想看看How to use Formatted Text Fields和How to use Spinners它可能會爲您提供更好的功能來實現您的目標

已更新，例如想法如何計算結果值

import java.awt.BorderLayout; 
import java.awt.EventQueue; 
import java.awt.GridBagLayout; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import javax.swing.DefaultComboBoxModel; 
import javax.swing.JButton; 
import javax.swing.JComboBox; 
import javax.swing.JFrame; 
import javax.swing.JLabel; 
import javax.swing.JPanel; 
import javax.swing.JTextField; 
import javax.swing.UIManager; 
import javax.swing.UnsupportedLookAndFeelException; 

public class QuickCalc { 

    public static void main(String[] args) { 
     new QuickCalc(); 
    } 

    public QuickCalc() { 
     EventQueue.invokeLater(new Runnable() { 
      @Override 
      public void run() { 
       try { 
        UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); 
       } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) { 
       } 

       JFrame frame = new JFrame("Testing"); 
       frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
       frame.setLayout(new BorderLayout()); 
       frame.add(new TestPane()); 
       frame.pack(); 
       frame.setLocationRelativeTo(null); 
       frame.setVisible(true); 
      } 
     }); 
    } 

    public class TestPane extends JPanel { 

     private JTextField numField1; 
     private JTextField numField2; 
     private JComboBox cbModifier; 
     private JLabel lblResult; 

     private JButton equals; 

     public TestPane() { 

      numField1 = new JTextField(4); 
      numField2 = new JTextField(4); 
      cbModifier = new JComboBox(); 
      equals = new JButton("="); 
      lblResult = new JLabel("?"); 

      DefaultComboBoxModel<String> model = new DefaultComboBoxModel<>(); 
      model.addElement("+"); 
      model.addElement("-"); 
      model.addElement("/"); 
      model.addElement("x"); 
      cbModifier.setModel(model); 

      setLayout(new GridBagLayout()); 
      add(numField1); 
      add(cbModifier); 
      add(numField2); 
      add(equals); 
      add(lblResult); 

      equals.addActionListener(new ActionListener() { 

       @Override 
       public void actionPerformed(ActionEvent e) { 
        try { 
         int num1 = Integer.parseInt(numField1.getText()); 
         int num2 = Integer.parseInt(numField2.getText()); 

         // Make your calculations here... 
         // Update the lblResult with the resulting value... 
         lblResult.setText(String.valueOf(42));       
        } catch (NumberFormatException nfe) { 
         nfe.printStackTrace(); 
         lblResult.setText("Bad numbers"); 
        } 
       }      
      }); 
     } 
    } 
}