逆波兰表达式的产生及计算

JAVA Code

RPN_Operation.java

package test3;public class RPN_Operation {    private char[] expChar = new char[100];// 表达式栈    private int expPointer = 0;// 表达式栈指针    private char[] ariStack = new char[100];// 运算符栈    private int top = 0;// 运算符栈指针    private char[] exitChar = new char[100];// 输出栈    private int exitPointer = 0;// 输出栈指针    private String[][] dataStrings = new String[100][5];// 表格数据 100行5列    private String tempString = new String();// 临时字符串    private String result = new String();// 结果字符串    private int row = 0;// 表格数据行    private String computeValue = new String();// 计算值    private final char[] Arithmetic = { '+', '-', '*', '/', '(', ')', '#' };// 运算符    private final char[] Letter = { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h',            'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u',            'v', 'w', 'x', 'y', 'z', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',            'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U',            'V', 'W', 'X', 'Y', 'Z' };// 字母表    private final char[] Digit = { '1', '2', '3', '4', '5', '6', '7', '8', '9',            '0' };// 数字表    public RPN_Operation() {        for (int i = 0; i < 100; i++) {            for (int j = 0; j < 5; j++) {                dataStrings[i][j] = new String();//每一个表格数据都是一个String                dataStrings[i][j] = "";//都赋为空            }        }    }    // 判断字符是否为字母    public boolean isLetter(char word) {        int N = 0;        while (N < Letter.length) {            if (word == Letter[N]) {                return true;            }            N++;        }        return false;    }    // 判断字符是否为数字    public boolean isDigit(char word) {        int N = 0;        while (N < Digit.length) {            if (word == Digit[N]) {                return true;            }            N++;        }        return false;    }    // 判断字符是否为算数运算符    public boolean isArithmetic(char word) {        int N = 0;        while (N < Arithmetic.length) {            if (word == Arithmetic[N]) {                return true;            }            N++;        }        return false;    }    // 输出剩余字符串    public void printExpChar() {        tempString = new String();        for (int i = expPointer; i < expChar.length; i++) {            tempString += expChar[i];            System.out.print(expChar[i]);            result += expChar[i];        }        System.out.print("\t\t");        result += "\t\t";    }    // 输出符号栈    public void printAriStack() {        tempString = new String();        for (int i = 0; i < top; i++) {            tempString += ariStack[i];            System.out.print(ariStack[i]);            result += ariStack[i];        }        System.out.print("\t\t");        result += "\t\t";    }    // 输出逆波兰式    public void printExitChar() {        tempString = new String();        for (int i = 0; i < exitPointer; i++) {            tempString += exitChar[i];            System.out.print(exitChar[i]);            result += exitChar[i];        }        System.out.print("\r\n");        result += "\r\n";    }    // 检查输入的中缀表达式中的字符是否合法    public boolean checkString(String checkString) {        char ch;        for (int i = 0; i < checkString.length(); i++) {            ch = checkString.charAt(i);//把checkString中的第i个字符赋给临时字符ch            //charAt(int index)方法是一个能够用来检索特定索引下的字符的String实例的方法.            if (isLetter(ch)) {                continue;            } else if (isDigit(ch)) {                continue;            } else if (isArithmetic(ch)) {                continue;            } else {                return false;            }        }        return true;    }    // 逆波兰分析    public void RPNAnalysis(String expression) {        expChar = expression.toCharArray();        char ch = expChar[expPointer++];        int temp = 0;        if (checkString(expression)) {            System.out.print("步骤\t当前符号\t输入区\t\t运算符号栈\t\t输出区\r\n");            result += "步骤\t当前符号\t输入区\t\t运算符号栈\t\t输出区\r\n";            while (ch != '#') {                if (isArithmetic(ch)) {                    switch (ch) {                    case '(':                        ariStack[top++] = ch;                        System.out.print(row + "\t" + ch + "\t");                        result += row + "\t" + ch + "\t";                        dataStrings[row][0] = row + "";                        dataStrings[row][1] = String.valueOf(ch);                        printExpChar();                        dataStrings[row][2] = tempString;                        printAriStack();                        dataStrings[row][3] = tempString;                        printExitChar();                        dataStrings[row][4] = tempString;                        row++;                        break;                    case ')':                        while (ariStack[--top] != '(') {                            exitChar[exitPointer++] = ariStack[top];                            System.out.print(row + "\t" + ch + "\t");                            result += row + "\t" + ch + "\t";                            dataStrings[row][0] = row + "";                            dataStrings[row][1] = String.valueOf(ch);                            printExpChar();                            dataStrings[row][2] = tempString;                            printAriStack();                            dataStrings[row][3] = tempString;                            printExitChar();                            dataStrings[row][4] = tempString;                            row++;                        }                        System.out.print(row + "\t" + ch + "\t");                        dataStrings[row][0] = row + "";                        result += row + "\t" + ch + "\t";                        dataStrings[row][1] = String.valueOf(ch);                        printExpChar();                        dataStrings[row][2] = tempString;                        printAriStack();                        dataStrings[row][3] = tempString;                        printExitChar();                        dataStrings[row][4] = tempString;                        row++;                        break;                    case '+':                    case '-':                        temp = top - 1;                        if (temp >= 0                                && (ariStack[temp] == '*' || ariStack[temp] == '/')) {                            exitChar[exitPointer++] = ariStack[temp];                            top--;                        } else if (temp >= 0                                && (ariStack[temp] == '-' || ariStack[temp] == '+')                                && (expChar[expPointer + 1] != '*' || expChar[expPointer + 1] != '/')) {                            exitChar[exitPointer++] = ariStack[temp];                            top--;                        }                        while (top < 0 && ariStack[temp] != '(') {                            exitChar[exitPointer++] = ariStack[temp];                            top--;                        }                        ariStack[top++] = ch;                        System.out.print(row + "\t" + ch + "\t");                        result += row + "\t" + ch + "\t";                        dataStrings[row][0] = row + "";                        dataStrings[row][1] = String.valueOf(ch);                        printExpChar();                        dataStrings[row][2] = tempString;                        printAriStack();                        dataStrings[row][3] = tempString;                        printExitChar();                        dataStrings[row][4] = tempString;                        row++;                        break;                    case '*':                    case '/':                        temp = top - 1;                        if (temp >= 0                                && (ariStack[temp] == '*' || ariStack[temp] == '/')) {                            exitChar[exitPointer++] = ariStack[temp];                            top--;                        }                        ariStack[top++] = ch;                        System.out.print(row + "\t" + ch + "\t");                        result += row + "\t" + ch + "\t";                        dataStrings[row][0] = row + "";                        dataStrings[row][1] = String.valueOf(ch);                        printExpChar();                        dataStrings[row][2] = tempString;                        printAriStack();                        dataStrings[row][3] = tempString;                        printExitChar();                        dataStrings[row][4] = tempString;                        row++;                        break;                    default:                        break;                    }                } else if (isLetter(ch) || isDigit(ch)) {                    exitChar[exitPointer++] = ch;                    System.out.print(row + "\t" + ch + "\t");                    result += row + "\t" + ch + "\t";                    dataStrings[row][0] = row + "";                    dataStrings[row][1] = String.valueOf(ch);                    printExpChar();                    dataStrings[row][2] = tempString;                    printAriStack();                    dataStrings[row][3] = tempString;                    printExitChar();                    dataStrings[row][4] = tempString;                    row++;                }                ch = expChar[expPointer++];            }            while (top != 0) {                temp = top - 1;                if (ariStack[temp] == '(') {                    top--;                    continue;                }                exitChar[exitPointer++] = ariStack[--top];                System.out.print(row + "\t" + ch + "\t");                result += row + "\t" + ch + "\t";                dataStrings[row][0] = row + "";                dataStrings[row][1] = String.valueOf(ch);                printExpChar();                dataStrings[row][2] = tempString;                printAriStack();                dataStrings[row][3] = tempString;                printExitChar();                dataStrings[row][4] = tempString;                row++;            }        }    }    // 计算值    public void computeValue() {        int stack[] = new int[100];        exitChar[exitPointer++] = '#';        char ch;        int i = 0, top = 0;        ch = exitChar[i++];        while (ch != '#') {            switch (ch) {            case '+':                computeValue += stack[top - 1] + " + " + stack[top];                stack[top - 1] = stack[top - 1] + stack[top];                computeValue += " := " + stack[top - 1] + "\r\n";                top--;                break;            case '-':                computeValue += stack[top - 1] + " - " + stack[top];                stack[top - 1] = stack[top - 1] - stack[top];                computeValue += " := " + stack[top - 1] + "\r\n";                top--;                break;            case '*':                computeValue += stack[top - 1] + " * " + stack[top];                stack[top - 1] = stack[top - 1] * stack[top];                computeValue += " := " + stack[top - 1] + "\r\n";                top--;                break;            case '/':                computeValue += stack[top - 1] + " / " + stack[top];                stack[top - 1] = stack[top - 1] / stack[top];                computeValue += " := " + stack[top - 1] + "\r\n";                top--;                break;            default:                top++;                stack[top] = ch - '0';                break;            }            ch = exitChar[i++];        }        computeValue += "结果：" + stack[top];        System.out.print(computeValue);    }    public int getRow() {        return row;    }    public void setRow(int row) {        this.row = row;    }    public String[][] getDataStrings() {        return dataStrings;    }    public void setDataStrings(String[][] dataStrings) {        this.dataStrings = dataStrings;    }    public String getResult() {        return result;    }    public void setResult(String result) {        this.result = result;    }    public char[] getExitChar() {        return exitChar;    }    public void setExitChar(char[] exitChar) {        this.exitChar = exitChar;    }    public String getcomputeValue() {        return computeValue;    }    public void setcomputeValue(String computeValue) {        this.computeValue = computeValue;    }}

RPNSWT.java

package test3;import java.io.*;import org.eclipse.swt.SWT;//这儿必须要添加swt的jar包到路径中来import org.eclipse.swt.custom.ScrolledComposite;import org.eclipse.swt.custom.TableEditor;import org.eclipse.swt.events.*;import org.eclipse.swt.graphics.*;import org.eclipse.swt.widgets.*;//import com.swtdesigner.SWTResourceManager;public class RPNSWT {    protected Shell shell;    private Text text;    private Table varTable;    private Text resultText;    private Table resultTable;    private MessageBox messageBox;    private TableEditor editor;    private String result = "";    private File sourceFile = null;    private RPN_Operation mOperation;//定义一个RPN_Operation类的对象    private String analysisString;    String computeValueString = new String();    private int varTableRow = 0;    private char[] varTableVar;    private char[] exitChar;    /**     * Launch the application.     *      * @param args     */    public static void main(String[] args) {        try {            RPNSWT window = new RPNSWT();            window.open();        } catch (Exception e) {            e.printStackTrace();        }    }    /**     * Open the window.     */    public void open() {        Display display = Display.getDefault();        createContents();        shell.open();        shell.layout();        while (!shell.isDisposed()) {            if (!display.readAndDispatch()) {                display.sleep();            }        }    }    /**     * Create contents of the window.     */    protected void createContents() {        shell = new Shell();        shell.setSize(500, 554);        shell.setText("逆波兰表达式的产生及计算");        Menu menu = new Menu(shell, SWT.BAR);        shell.setMenuBar(menu);        MenuItem menuItem = new MenuItem(menu, SWT.NONE);        menuItem.addSelectionListener(new SelectionAdapter() {            @Override            public void widgetSelected(SelectionEvent e) {                newTextTable();            }        });        menuItem.setText("\u65B0\u5EFA");        MenuItem menuItem_1 = new MenuItem(menu, SWT.NONE);        menuItem_1.addSelectionListener(new SelectionAdapter() {            @Override            public void widgetSelected(SelectionEvent e) {                openFile();            }        });        menuItem_1.setText("\u6253\u5F00");        MenuItem menuItem_2 = new MenuItem(menu, SWT.NONE);        menuItem_2.addSelectionListener(new SelectionAdapter() {            @Override            public void widgetSelected(SelectionEvent e) {                try {                    analysis();                } catch (Exception e2) {                    e2.printStackTrace();                }            }        });        menuItem_2.setText("\u5206\u6790");        MenuItem menuItem_6 = new MenuItem(menu, SWT.NONE);        menuItem_6.addSelectionListener(new SelectionAdapter() {            @Override            public void widgetSelected(SelectionEvent e) {                try {                    computeValue();                } catch (Exception e2) {                    e2.printStackTrace();                }            }        });        menuItem_6.setText("\u8BA1\u7B97");        MenuItem menuItem_3 = new MenuItem(menu, SWT.NONE);        menuItem_3.addSelectionListener(new SelectionAdapter() {            @Override            public void widgetSelected(SelectionEvent e) {                saveFile();            }        });        menuItem_3.setText("\u4FDD\u5B58");        MenuItem menuItem_4 = new MenuItem(menu, SWT.NONE);        menuItem_4.addSelectionListener(new SelectionAdapter() {            @Override            public void widgetSelected(SelectionEvent e) {                shell.dispose();            }        });        menuItem_4.setText("\u9000\u51FA");        ScrolledComposite scrolledComposite = new ScrolledComposite(shell,                SWT.BORDER | SWT.H_SCROLL | SWT.V_SCROLL);        scrolledComposite.setBounds(10, 10, 202, 119);        scrolledComposite.setExpandHorizontal(true);        scrolledComposite.setExpandVertical(true);        text = new Text(scrolledComposite, SWT.BORDER);        scrolledComposite.setContent(text);        scrolledComposite                .setMinSize(text.computeSize(SWT.DEFAULT, SWT.DEFAULT));        varTable = new Table(shell, SWT.BORDER | SWT.FULL_SELECTION);        varTable.setBounds(218, 10, 127, 119);        varTable.setHeaderVisible(true);        varTable.setLinesVisible(true);        editor = new TableEditor(varTable);        editor.horizontalAlignment = SWT.LEFT;        editor.grabHorizontal = true;        createEditorContents();        TableColumn tableColumn = new TableColumn(varTable, SWT.NONE);        tableColumn.setWidth(61);        tableColumn.setText("\u53D8\u91CF");        TableColumn tblclmnNewColumn = new TableColumn(varTable, SWT.NONE);        tblclmnNewColumn.setWidth(61);        tblclmnNewColumn.setText("\u503C");        ScrolledComposite scrolledComposite_1 = new ScrolledComposite(shell,                SWT.BORDER | SWT.H_SCROLL | SWT.V_SCROLL);        scrolledComposite_1.setBounds(351, 10, 123, 119);        scrolledComposite_1.setExpandHorizontal(true);        scrolledComposite_1.setExpandVertical(true);        resultText = new Text(scrolledComposite_1, SWT.BORDER | SWT.H_SCROLL                | SWT.V_SCROLL | SWT.CANCEL);        //resultText.setBackground(SWTResourceManager        //      .getColor(SWT.COLOR_LIST_BACKGROUND));        resultText.setEditable(false);        scrolledComposite_1.setContent(resultText);        scrolledComposite_1.setMinSize(resultText.computeSize(SWT.DEFAULT,                SWT.DEFAULT));        resultTable = new Table(shell, SWT.BORDER | SWT.FULL_SELECTION);        resultTable.setBounds(10, 135, 464, 356);        resultTable.setHeaderVisible(true);        resultTable.setLinesVisible(true);        TableColumn tblclmnNewColumn_1 = new TableColumn(resultTable, SWT.NONE);        tblclmnNewColumn_1.setResizable(false);        tblclmnNewColumn_1.setWidth(59);        tblclmnNewColumn_1.setText("\u6B65\u9AA4");        TableColumn tblclmnNewColumn_2 = new TableColumn(resultTable, SWT.NONE);        tblclmnNewColumn_2.setWidth(100);        tblclmnNewColumn_2.setText("\u5F53\u524D\u7B26\u53F7");        TableColumn tblclmnNewColumn_3 = new TableColumn(resultTable, SWT.NONE);        tblclmnNewColumn_3.setWidth(100);        tblclmnNewColumn_3.setText("\u8F93\u5165\u533A");        TableColumn tblclmnNewColumn_4 = new TableColumn(resultTable, SWT.NONE);        tblclmnNewColumn_4.setWidth(100);        tblclmnNewColumn_4.setText("\u8FD0\u7B97\u7B26\u53F7\u6808");        TableColumn tblclmnNewColumn_5 = new TableColumn(resultTable, SWT.NONE);        tblclmnNewColumn_5.setWidth(100);        tblclmnNewColumn_5.setText("\u8F93\u51FA\u533A");    }    public void openFile() {        FileDialog openFileDialog = new FileDialog(shell, SWT.OPEN);        openFileDialog.setText("选择需要分析的文件");        openFileDialog.setFilterExtensions(new String[] { "*.txt" });        openFileDialog.setFilterNames(new String[] { "txt文本文件(*.txt)" });        openFileDialog.setFilterPath("D:\\");        String selectedOpenFile = openFileDialog.open();        this.result = "";        if (selectedOpenFile != null) {            sourceFile = new File(selectedOpenFile);            try {                FileReader fileReader = new FileReader(sourceFile);                BufferedReader reader = new BufferedReader(fileReader);                StringBuffer stringBuffer = new StringBuffer();                String lineString = null;                while ((lineString = reader.readLine()) != null) {                    stringBuffer.append(lineString);                    stringBuffer.append("\n");                }                text.setText(stringBuffer.toString());                shell.setText("逆波兰表达式分析器 - " + openFileDialog.getFileName());                fileReader.close();                varTable.removeAll();                resultTable.removeAll();            } catch (Exception e) {                e.printStackTrace();            }        } else {            messageBox = new MessageBox(shell, SWT.ICON_WARNING);            messageBox.setMessage("文件未载入！请重新打开需要分析的文件！");            messageBox.setText("提示");            messageBox.open();        }    }    public void newTextTable() {        this.result = "";        this.text.setText("");        this.resultText.setText("");        this.varTable.removeAll();        this.resultTable.removeAll();    }    public void saveFile() {        if (result != "") {            result += "\r\n" + computeValueString;            FileWriter fileWriter = null;            try {                fileWriter = new FileWriter("Result.txt");                fileWriter.write(result);            } catch (Exception e) {                e.printStackTrace();            } finally {                try {                    Runtime runtime = Runtime.getRuntime();                    messageBox = new MessageBox(shell);                    messageBox.setMessage("保存成功！");                    messageBox.setText("提示");                    fileWriter.flush();                    fileWriter.close();                    messageBox.open();                    sourceFile = new File("Result.txt");                    runtime.exec("rundll32 url.dll FileProtocolHandler "                            + sourceFile.getAbsolutePath());                } catch (Exception e2) {                    e2.printStackTrace();                }            }        } else {            messageBox = new MessageBox(shell, SWT.ICON_WARNING);            messageBox.setMessage("未分析，保存失败！");            messageBox.setText("提示");            messageBox.open();        }    }    public void analysis() {        mOperation = new RPN_Operation();        this.resultTable.removeAll();        this.varTable.removeAll();        this.resultText.setText("");        this.analysisString = text.getText();        this.result = "";        boolean flag = false;        if (mOperation.checkString(this.analysisString)) {            flag = true;        }        if (this.analysisString.equals("")) {            messageBox = new MessageBox(shell, SWT.ICON_WARNING);            messageBox.setMessage("请输入需要分析的字符串或打开需要分析的文件！");            messageBox.setText("提示");            messageBox.open();        } else if (flag) {            if (analysisString.charAt(analysisString.length() - 1) != '#') {                analysisString += "#";            }            this.result = "";            mOperation.RPNAnalysis(this.analysisString);            for (int i = 0; i < mOperation.getRow(); i++) {                TableItem item = new TableItem(resultTable, SWT.NULL);                for (int j = 0; j < 5; j++) {                    item.setText(j, mOperation.getDataStrings()[i][j]);                }            }            this.result = mOperation.getResult();            showVariable();        } else {            messageBox = new MessageBox(shell, SWT.ICON_WARNING);            messageBox.setMessage("输入的字符串有错误！");            messageBox.setText("提示");            messageBox.open();        }    }    public void showVariable() {        for (int i = 0; i < analysisString.length(); i++) {            if (mOperation.isLetter(analysisString.charAt(i))                    || mOperation.isDigit(analysisString.charAt(i))) {                varTableRow++;            }        }        varTableVar = new char[varTableRow];        varTableRow = 0;        for (int i = 0; i < analysisString.length(); i++) {            if (mOperation.isLetter(analysisString.charAt(i))                    || mOperation.isDigit(analysisString.charAt(i))) {                varTableVar[varTableRow] = analysisString.charAt(i);                varTableRow++;            }        }        boolean flag = true;        for (int i = 0; i < varTableRow; i++) {            for (int j = 0; j < varTable.getItems().length; j++) {                if (varTableVar[i] == varTable.getItems()[j].getText()                        .charAt(0)) {                    flag = false;                }            }            if (flag) {                TableItem item = new TableItem(varTable, SWT.NULL);                item.setText(0, String.valueOf(varTableVar[i]));                if (mOperation.isDigit(varTableVar[i])) {                    item.setText(1, String.valueOf(varTableVar[i]));                } else {                    item.setText(1, "");                }            }            flag = true;        }    }    public void createEditorContents() {        varTable.addMouseListener(new MouseAdapter() {            public void mouseDown(MouseEvent event) {                Control old = editor.getEditor();                if (old != null) {                    old.dispose();                }                Point point = new Point(event.x, event.y);                final TableItem item = varTable.getItem(point);                if (item != null) {                    int column = -1;                    for (int i = 1, n = varTable.getColumnCount(); i < n; i++) {                        Rectangle rectangle = item.getBounds(i);                        if (rectangle.contains(point)) {                            column = i;                            break;                        }                    }                    if (column >= 0) {                        final Text text = new Text(varTable, SWT.NONE);                        text.setText(item.getText(column));                        text.selectAll();                        text.setFocus();                        editor.setEditor(text, item, column);                        final int col = column;                        text.addModifyListener(new ModifyListener() {                            @Override                            public void modifyText(ModifyEvent arg0) {                                item.setText(col, text.getText());                            }                        });                    }                }            }        });    }    public char setValue(char var) {        for (int i = 0; i < varTable.getItems().length; i++) {            if (var == varTable.getItems()[i].getText().charAt(0)) {                return varTable.getItems()[i].getText(1).charAt(0);            }        }        return var;    }    public void computeValue() {        if (result == "") {            messageBox = new MessageBox(shell, SWT.ICON_WARNING);            messageBox.setMessage("计算失败！请先分析！");            messageBox.setText("提示");            messageBox.open();        } else {            exitChar = new char[mOperation.getExitChar().length];            exitChar = mOperation.getExitChar();            for (int i = 0; i < exitChar.length; i++) {                exitChar[i] = setValue(exitChar[i]);            }            mOperation.setExitChar(exitChar);            mOperation.computeValue();            computeValueString = mOperation.getcomputeValue();            System.out.print(computeValueString);            resultText.setText(computeValueString);        }    }}

结果截图

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细节总结

1.使用swt需注意的东西。

SWT(Standard Widget Toolkit) Standard Widget Toolkit是一个开源的GUI编程框架，与AWT/Swing有相似的用处，著名的开源IDE-eclipse就是用SWT开发的。 在SWT之前，Sun已经提供了一个跨平台GUI开发工具包AWT (Abstract Windowing Toolkit).AWT框架底层使用原生窗口部件(native widgets)构建，只能使用各个平台窗口部件的子集。

import org.eclipse.swt.SWT;//这儿导入SWT包时必须要添加swt的jar包到路径中来
方法：

F:\开发工具\JAVA开发\eclipse 这个路径就是我安装eclipse的路径，swt的jar包不用到网上下载，在F:\开发工具\JAVA开发\eclipse\plugins 下就有，直接添加到环境中即可。

2.//import com.swtdesigner.SWTResourceManager;
//resultText.setBackground(SWTResourceManager
// .getColor(SWT.COLOR_LIST_BACKGROUND));