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Java 为什么找不到txtDisplay（）方法？

java

Java 为什么找不到txtDisplay（）方法？,java,Java,我想做一个java计算器。我用netbeans编写代码。当我构建源代码时，它会显示错误： C:\Users\Nishan\Documents\javawork\Calculator\src\Calculation\Calculation.java:215: 错误：找不到符号 txtDisplay.setText（btn1Text）；符号：变量TXT显示位置：类别计算 这是我的密码： private void btn1ActionPerformed(java.awt.event.ActionEve

我想做一个java计算器。我用netbeans编写代码。当我构建源代码时，它会显示错误：

C:\Users\Nishan\Documents\javawork\Calculator\src\Calculation\Calculation.java:215: 错误：找不到符号 txtDisplay.setText（btn1Text）；符号：变量TXT显示位置：类别计算

这是我的密码：

private void btn1ActionPerformed(java.awt.event.ActionEvent evt) {                                     
    String btn1Text;
    btn1Text = txtDisplay.getText() + btn1.getText();
txtDisplay.setText(btn1Text);
}



  **/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package Calculation;

/**
 *
 * @author Nishan
 */
public class Calculation extends javax.swing.JFrame {

    double firstnum;
    double secondnum;
    double result;
    String operation;
    public Calculation() {
        initComponents();
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jTextField1 = new javax.swing.JTextField();
        btn1 = new javax.swing.JButton();
        btn2 = new javax.swing.JButton();
        btn3 = new javax.swing.JButton();
        btn4 = new javax.swing.JButton();
        btn5 = new javax.swing.JButton();
        btn6 = new javax.swing.JButton();
        btn7 = new javax.swing.JButton();
        btn8 = new javax.swing.JButton();
        btn9 = new javax.swing.JButton();
        btn10 = new javax.swing.JButton();
        btn11 = new javax.swing.JButton();
        btn12 = new javax.swing.JButton();
        btn13 = new javax.swing.JButton();
        btn14 = new javax.swing.JButton();
        btn15 = new javax.swing.JButton();
        btn16 = new javax.swing.JButton();
        btn18 = new javax.swing.JButton();
        btn17 = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jTextField1.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        jTextField1.setHorizontalAlignment(javax.swing.JTextField.RIGHT);

        btn1.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn1.setText("1");
        btn1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btn1ActionPerformed(evt);
            }
        });

        btn2.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn2.setText("2");

        btn3.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn3.setText("3");

        btn4.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn4.setText("+");

        btn5.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn5.setText("4");

        btn6.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn6.setText("5");

        btn7.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn7.setText("6");

        btn8.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn8.setText("-");

        btn9.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn9.setText("7");

        btn10.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn10.setText("8");

        btn11.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn11.setText("9");

        btn12.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn12.setText("*");

        btn13.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn13.setText(".");

        btn14.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn14.setText("0");

        btn15.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn15.setText("C");

        btn16.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn16.setText("/");

        btn18.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn18.setText("=");

        btn17.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn17.setText("+-/");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jTextField1)
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(btn1)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(btn2)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(btn3)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(btn4, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
                    .addGroup(layout.createSequentialGroup()
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
                            .addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createSequentialGroup()
                                .addComponent(btn14)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                .addComponent(btn13, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
                            .addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createSequentialGroup()
                                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
                                    .addComponent(btn5, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                                    .addComponent(btn9, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                                    .addComponent(btn6, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                                    .addComponent(btn10, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))))
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addGroup(layout.createSequentialGroup()
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                                    .addComponent(btn7, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                                    .addComponent(btn11, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                                    .addComponent(btn8, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                                    .addComponent(btn12, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)))
                            .addGroup(layout.createSequentialGroup()
                                .addGap(6, 6, 6)
                                .addComponent(btn15, javax.swing.GroupLayout.PREFERRED_SIZE, 45, javax.swing.GroupLayout.PREFERRED_SIZE)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                                .addComponent(btn16, javax.swing.GroupLayout.PREFERRED_SIZE, 53, javax.swing.GroupLayout.PREFERRED_SIZE))
                            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                                .addComponent(btn18, javax.swing.GroupLayout.PREFERRED_SIZE, 99, javax.swing.GroupLayout.PREFERRED_SIZE)))))
                .addContainerGap())
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                    .addContainerGap()
                    .addComponent(btn17, javax.swing.GroupLayout.PREFERRED_SIZE, 99, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addContainerGap(125, Short.MAX_VALUE)))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(btn1)
                    .addComponent(btn2)
                    .addComponent(btn3)
                    .addComponent(btn4))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(btn5)
                    .addComponent(btn6)
                    .addComponent(btn7)
                    .addComponent(btn8))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(btn9)
                    .addComponent(btn10)
                    .addComponent(btn11)
                    .addComponent(btn12))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(btn14)
                    .addComponent(btn13)
                    .addComponent(btn15)
                    .addComponent(btn16))
                .addGap(16, 16, 16)
                .addComponent(btn18)
                .addContainerGap(24, Short.MAX_VALUE))
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                    .addContainerGap(240, Short.MAX_VALUE)
                    .addComponent(btn17)
                    .addGap(23, 23, 23)))
        );

        pack();
    }// </editor-fold>                        

    private void btn1ActionPerformed(java.awt.event.ActionEvent evt) {                                     
        String btn1Text;
        btn1Text = txtDisplay.getText() + btn1.getText();
    txtDisplay.setText(btn1Text);
    }                                    

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(Calculation.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(Calculation.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(Calculation.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(Calculation.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new Calculation().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify                     
    private javax.swing.JButton btn1;
    private javax.swing.JButton btn10;
    private javax.swing.JButton btn11;
    private javax.swing.JButton btn12;
    private javax.swing.JButton btn13;
    private javax.swing.JButton btn14;
    private javax.swing.JButton btn15;
    private javax.swing.JButton btn16;
    private javax.swing.JButton btn17;
    private javax.swing.JButton btn18;
    private javax.swing.JButton btn2;
    private javax.swing.JButton btn3;
    private javax.swing.JButton btn4;
    private javax.swing.JButton btn5;
    private javax.swing.JButton btn6;
    private javax.swing.JButton btn7;
    private javax.swing.JButton btn8;
    private javax.swing.JButton btn9;
    private javax.swing.JTextField jTextField1;
    // End of variables declaration                   
}
**

private void btn1ActionPerformed（java.awt.event.ActionEvent evt）{
字符串btn1文本；
btn1Text=txtDisplay.getText（）+btn1.getText（）；
txtDisplay.setText（btn1Text）；
}
**/*
*要更改此许可证标题，请在“项目属性”中选择“许可证标题”。
*要更改此模板文件，请选择工具|模板
*然后在编辑器中打开模板。
*/
包装计算；
/**
*
*@作者尼山
*/
公共类计算扩展了javax.swing.JFrame{
双第一数；
双秒数；
双重结果；
串操作；
公共计算（）{
初始化组件（）；
}
/**
*从构造函数中调用此方法来初始化表单。
*警告：不要修改此代码。此方法的内容始终为
*由表单编辑器重新生成。
*/
@抑制警告（“未选中”）
//                           
私有组件（）{
jTextField1=newjavax.swing.JTextField（）；
btn1=newjavax.swing.JButton（）；
btn2=newjavax.swing.JButton（）；
btn3=newjavax.swing.JButton（）；
btn4=newjavax.swing.JButton（）；
btn5=newjavax.swing.JButton（）；
btn6=newjavax.swing.JButton（）；
btn7=newjavax.swing.JButton（）；
btn8=newjavax.swing.JButton（）；
btn9=newjavax.swing.JButton（）；
btn10=newjavax.swing.JButton（）；
btn11=newjavax.swing.JButton（）；
btn12=newjavax.swing.JButton（）；
btn13=newjavax.swing.JButton（）；
btn14=newjavax.swing.JButton（）；
btn15=newjavax.swing.JButton（）；
btn16=newjavax.swing.JButton（）；
btn18=newjavax.swing.JButton（）；
btn17=newjavax.swing.JButton（）；
setDefaultCloseOperation（javax.swing.WindowConstants.EXIT_ON_CLOSE）；
jTextField1.setFont（新的java.awt.Font（“Tahoma”，1，24））；//NOI18N
jTextField1.setHorizontalAlignment（javax.swing.JTextField.RIGHT）；
setFont（新的java.awt.Font（“Tahoma”，1，24））；//NOI18N
btn1.setText（“1”）；
addActionListener（新的java.awt.event.ActionListener（）{
public void actionPerformed（java.awt.event.ActionEvent evt）{
执行的BTN1操作（evt）；
}
});
setFont（新的java.awt.Font（“Tahoma”，1，24））；//NOI18N
btn2.setText（“2”）；
setFont（新的java.awt.Font（“Tahoma”，1，24））；//NOI18N
btn3.setText（“3”）；
setFont（新的java.awt.Font（“Tahoma”，1，24））；//NOI18N
btn4.setText（“+”）；
setFont（新的java.awt.Font（“Tahoma”，1，24））；//NOI18N
btn5.setText（“4”）；
setFont（新的java.awt.Font（“Tahoma”，1，24））；//NOI18N
btn6.setText（“5”）；
setFont（新的java.awt.Font（“Tahoma”，1，24））；//NOI18N
btn7.setText（“6”）；
setFont（新的java.awt.Font（“Tahoma”，1，24））；//NOI18N
btn8.setText（“-”）；
setFont（新的java.awt.Font（“Tahoma”，1，24））；//NOI18N
btn9.setText（“7”）；
setFont（新的java.awt.Font（“Tahoma”，1，24））；//NOI18N
btn10.setText（“8”）；
setFont（新的java.awt.Font（“Tahoma”，1，24））；//NOI18N
btn11.setText（“9”）；
setFont（新的java.awt.Font（“Tahoma”，1，24））；//NOI18N
btn12.setText（“*”）；
setFont（新的java.awt.Font（“Tahoma”，1，24））；//NOI18N
btn13.setText（“.”）；
setFont（新的java.awt.Font（“Tahoma”，1，24））；//NOI18N
btn14.setText（“0”）；
setFont（新的java.awt.Font（“Tahoma”，1，24））；//NOI18N
btn15.setText（“C”）；
setFont（新的java.awt.Font（“Tahoma”，1，24））；//NOI18N
btn16.setText（“/”）；
setFont（新的java.awt.Font（“Tahoma”，1，24））；//NOI18N
btn18.setText（“=”）；
setFont（新的java.awt.Font（“Tahoma”，1，24））；//NOI18N
btn17.setText（“+-/”）；
javax.swing.GroupLayout=newjavax.swing.GroupLayout（getContentPane（））；
getContentPane（）.setLayout（布局）；
layout.setHorizontalGroup(
createParallelGroup（javax.swing.GroupLayout.Alignment.LEADING）
.addGroup（layout.createSequentialGroup（）
.addContainerGap（）
.addGroup（layout.createParallelGroup（javax.swing.GroupLayout.Alignment.LEADING）
.addComponent（jTextField1）
.addGroup（layout.createSequentialGroup（）
.addComponent（btn1）
.addPreferredGap（javax.swing.LayoutStyle.ComponentPlacement.RELATED）
.addComponent（btn2）
.addPreferredGap（javax.swing.LayoutStyle.ComponentPlacement.RELATED）
.addComponent（btn3）
.addPreferredGap（javax.swing.LayoutStyle.ComponentPlacement.RELATED）
.addComponent（btn4，javax.swing.GroupLayout.DEFAULT\u SIZE，javax.swing.GroupLayout.DEFAULT\u SIZE，Short.MAX\u VALUE））
.addGroup（layout.createSequentialGroup（）
.addGroup（layout.createParallelGroup（javax.swing.GroupLayout.Alignment.training，false）
.addGroup（javax.swing.GroupLayout.Alignment.LEADING，layout.createSequentialGroup（）
.addComponent（btn14）
.addPreferredGap（javax.swing.LayoutStyle.ComponentPlacement.RELATED）
.addComponent（btn13，javax.swing.GroupLayout.DEFAULT_SIZE，javax.sw