在另一个类实例中获取一个类实例的变量值答案

【问题标题】：Get a value of a variable of a class instance while being at another class instance在另一个类实例中获取一个类实例的变量值
【发布时间】：2023-03-28 19:32:01
【问题描述】：

我已经使用 jTable 实现了一个电子表格。现在我需要从另一个类的实例中获取该电子表格的单元格值。

我试图将当前对象的类扩展到包含 jTable 的类，但它给了我另一个包含 jTable 的类的实例。

有没有办法访问另一个类实例中的变量而不将当前对象的类扩展到该类？

提前谢谢你:)

package spreadsheet;

import java.awt.Dimension;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.DefaultCellEditor;
import javax.swing.JFrame;
import javax.swing.JTable;
import javax.swing.JTextField;
import javax.swing.ListSelectionModel;
import javax.swing.Timer;
import javax.swing.event.*;
import javax.swing.text.BadLocationException;

public class SpreadSheetUI extends javax.swing.JFrame implements TableModelListener {

public NewCell[][] cellArray=new NewCell[20][9];

public SpreadSheetUI() {

    initComponents();

    jTable1.setModel(new javax.swing.table.DefaultTableModel(
    new Object [][] {
        {1, null, null, null, null, null, null, null, null, null},
        {2, null, null, null, null, null, null, null, null, null},
        {3, null, null, null, null, null, null, null, null, null},
        {4, null, null, null, null, null, null, null, null, null},
        {5, null, null, null, null, null, null, null, null, null},
        {6, null, null, null, null, null, null, null, null, null},
        {7, null, null, null, null, null, null, null, null, null},
        {8, null, null, null, null, null, null, null, null, null},
        {9, null, null, null, null, null, null, null, null, null},
        {10, null, null, null, null, null, null, null, null, null},
        {11, null, null, null, null, null, null, null, null, null},
        {12, null, null, null, null, null, null, null, null, null},
        {13, null, null, null, null, null, null, null, null, null},
        {14, null, null, null, null, null, null, null, null, null},
        {15, null, null, null, null, null, null, null, null, null},
        {16, null, null, null, null, null, null, null, null, null},
        {17, null, null, null, null, null, null, null, null, null},
        {18, null, null, null, null, null, null, null, null, null},
        {19, null, null, null, null, null, null, null, null, null},
        {20, null, null, null, null, null, null, null, null, null}
    },
    new String [] {
        "", "A", "B", "C", "D", "E", "F", "G", "H", "I"
    }
    ) {
        boolean[] canEdit = new boolean [] {
            false, true, true, true, true, true, true, true, true, true
        };

        @Override
        public boolean isCellEditable(int rowIndex, int columnIndex) {
            return canEdit [columnIndex];
        }
    });

    jTable1.getModel().addTableModelListener(new TableModelListener() {
        @Override
        public void tableChanged(TableModelEvent e) {
            updateCellAddressText();
            updateFormulaBarText();
        }
    });
    jTable1.setCellSelectionEnabled(true);
    jTable1.getModel().addTableModelListener(this);
    jTable1.getColumnModel().getColumn(0).setPreferredWidth(20);
    jTable1.getColumnModel().getColumn(0).setResizable(false);

    //Create a column selection listener
    final ListSelectionModel sel = jTable1.getColumnModel().getSelectionModel();
    sel.addListSelectionListener(new ListSelectionListener(){
        @Override
        public void valueChanged(ListSelectionEvent e) {                
            //If a cell in column[0] is selected, deselect it and select the respecting row
            if (sel.isSelectedIndex(0))
                sel.setSelectionInterval(9,1);
            //System.out.println(sel.getMinSelectionIndex());

        }
    });

    ((JTextField) ((DefaultCellEditor) jTable1.getDefaultEditor(Object.class)).getComponent()).getDocument().addDocumentListener(
            new DocumentListener() {

                @Override
                public void insertUpdate(DocumentEvent de) {
                    try {
                        jTextFieldFormula.setText(de.getDocument().getText(0, de.getDocument().getLength()));
                    } catch (BadLocationException ex) {
                        Logger.getLogger(SpreadSheetUI.class.getName()).log(Level.SEVERE, null, ex);
                    }
                }

                @Override
                public void removeUpdate(DocumentEvent de) {
                    try {
                        jTextFieldFormula.setText(de.getDocument().getText(0, de.getDocument().getLength()));
                    } catch (BadLocationException ex) {
                        Logger.getLogger(SpreadSheetUI.class.getName()).log(Level.SEVERE, null, ex);
                    }
                }

                @Override
                public void changedUpdate(DocumentEvent de) {
                    try {
                        jTextFieldFormula.setText(de.getDocument().getText(0, de.getDocument().getLength()));
                    } catch (BadLocationException ex) {
                        Logger.getLogger(SpreadSheetUI.class.getName()).log(Level.SEVERE, null, ex);
                    }
                }

            }
    );

    Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
    this.setLocation(dim.width/2-this.getSize().width/2, dim.height/2-this.getSize().height/2);//location
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    this.setVisible(true);
}

package spreadsheet;

import java.awt.Frame;
import java.io.Serializable;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class NewCell implements Serializable {

//** fields
String userInput=null,dataType=null,calculatedValue=null;
String strArr[];
StringTokenizer tokenizer;
DataType data;   

//** constructor
public NewCell(String newData) {
    userInput=newData;
    //  two ways of tokenizing is used as the user may input,
    //  1.) A formula which needs to be calculated and then stored in a cell
    //  2.) A normal data which needs to be split into datatypes and stored
    //  user input is identified as a formula if the first character is "="
    if(userInput.startsWith("=")) {
        String pattern = "(.*)(\\d+)";
        String row,column;
        Pattern ptn = Pattern.compile(pattern);     // Create a Pattern object
        Matcher matcher;                            // Create Matcher object.
        tokenize("=^*/+-(),",true);

        ArrayList<String> outputList=new ArrayList<>();            
        Stack stackOperators=new Stack();
        String[] duplicateArr=new String[strArr.length-1];
        //insert every token except the starting '=' to 'duplicateArr'            
        for(int i=0;i<duplicateArr.length;i++){
            duplicateArr[i]=strArr[i+1];
            // In here I want to get the cell value of jTable1 
            // Example: Assume duplicateArr[i]="A1"
            // then I need the value of the cell in 1st row 2nd column
            // and then convert it to a string and give that value back
            // to the duplicateArr[i]
            //*********************************************************
            // Or else if I can get values from cellArray[][] in
            // jTable1 that's also fine.             
        }
        for (String strArr1 : duplicateArr) {
            if(strArr1.matches("-?\\d+(\\.\\d+)?"))
            //checks whether the element is numerical
            {
                outputList.add(strArr1);
            }else if(strArr1.equals("(")) {
                stackOperators.push(strArr1);
            }else if(strArr1.equals(")")) {
                while(!(String.valueOf(stackOperators.peek()).equals("("))){
                    outputList.add(String.valueOf(stackOperators.pop()));
                }
                stackOperators.pop();
            }else{
                while(!stackOperators.empty() && (operaorPrecedence(String.valueOf(stackOperators.peek()))>operaorPrecedence(strArr1))){
                    outputList.add(String.valueOf(stackOperators.pop()));
                }
                stackOperators.push(strArr1);
            }
        }
        while(!stackOperators.empty()){
            outputList.add(String.valueOf(stackOperators.pop()));
        }
        int currentIndex=0;
        float a,b;
        while(1!=outputList.size()){
            if(!outputList.get(currentIndex+2).matches("-?\\d+(\\.\\d+)?")){
                a=Float.parseFloat(outputList.remove(currentIndex));
                b=Float.parseFloat(outputList.remove(currentIndex));
                switch(outputList.get(currentIndex)){
                    case "+":
                        outputList.set(currentIndex,String.valueOf(a+b));
                        break;
                    case "-":
                        outputList.set(currentIndex,String.valueOf(a-b));
                        break;
                    case "*":
                        outputList.set(currentIndex,String.valueOf(a*b));
                        break;
                    case "/":
                        outputList.set(currentIndex,String.valueOf(a/b));
                        break;
                    case "^":
                        outputList.set(currentIndex,String.valueOf(Math.pow(a,b)));
                        break;
                }
                //check whether currentIndex+2 is larger than the maximum currentIndex of outputList
                if(outputList.size()-1<=currentIndex+2)
                    currentIndex--;
            }else{
                currentIndex++;
            }
        }
        tokenizer=null; //tokenizer is made null to escape the 'NotSerializableException'
                        //when calling for 'Save' or 'Open' methods
        calculatedValue=outputList.get(0);
        if(Float.valueOf(calculatedValue)==Math.ceil(Float.valueOf(calculatedValue))){
            calculatedValue=String.valueOf((int)Math.ceil(Float.valueOf(calculatedValue)));
            dataType="Integer Formula";
        }else{
            dataType="Float Formula";
        }

        //System.out.println(outputList.toString());
        /*
        if(strArr[1].equals("sum")) {}
        else if(strArr[1].equals("avg")) {}
        else if(strArr[1].equals("concat")) {}
        else {
        }*/
    }else{
        String datePattern="\\d{4}/\\d{1,2}/\\d{1,2}";
        if (userInput.matches(datePattern)) {
                //** Find DateDT inside the input
                data=new DateDT(userInput);
                dataType="Date";
        }else{
            try{
                //**Find IntegerDT inside the input
                data=new IntegerDT(Integer.parseInt(userInput));
                dataType="Integer";
            }catch(NumberFormatException nfe1){
                try{
                    //** Find FloatDT inside the input
                    data=new FloatDT(Float.valueOf(userInput));
                    dataType="Float";
                }catch(NumberFormatException nfe2){
                    //** Obviously userInput is StringDT
                    data=new StringDT(userInput);
                    dataType="String";
                }
            }
        }
    }
}

//** getters & setters
public String getUserInput() {
    return userInput;
}

public void setCalculatedValue(String calculatedValue) {
    this.calculatedValue = calculatedValue;
}

public String getCalculatedValue() {
    return calculatedValue;
}

public void setUserInput(String userInput) {
    this.userInput = userInput;
}

//** methods
private void tokenize(String delimiter,boolean delimStatus) {
    int j=0;
    tokenizer=new StringTokenizer(userInput, delimiter,delimStatus);
    strArr=new String[tokenizer.countTokens()];
    while(tokenizer.hasMoreTokens()){
        strArr[j]=tokenizer.nextToken();
        j++;
    }
}

private int operaorPrecedence(String Operator){
    switch(Operator){
        case "+":
            return 0;
        case "-":
            return 0;
        case "*":
            return 1;
        case "/":
            return 1;
        case "^":
            return 2;
        default:
            return -1;
    }
}

}

【问题讨论】：

请提供您正在使用的代码。这可能有助于明确您的问题是什么。
Composition 是一种方式，如果你不想使用Inheritance。
公共变量或getter和setter
好的。我已经写了我的课程。以及其中的部分代码。在 NewCell 类中，在 for 循环中，我引用了我面临的问题。谢谢你的时间:)

标签： java swing class variables jtable

【解决方案1】：

你必须试试这个逻辑。

 Class Jtable
private Object cellx;

public Object getCellx(){

return this.cellx; }
public setCellx(Object cellx){
this.cellx=cellx;}
}

和：

 Class AnotherClass
{
private Jtable jtable; 
getter and setter

public void function() {
this.jtable.getCellx();
  }
}

【讨论】：

【解决方案2】：

好的。我找到了答案。我们只需要像这样将SpreadSheetUI 类中的cellArray[][] 设为static 变量。

public static NewCell[][] cellArray=new NewCell[20][9];

然后来自NewCell类的实例；我们可以像这样访问cellArray[][] 的值。

SpreadSheetUI.cellArray[row][column].userInput=<Expression>;

或者，使用getter和setter；

String data=SpreadSheetUI.cellArray[row][column].getUserInput();

【讨论】：