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Данный пример сделан для демонстрации использования SWT из пакета Eclipse. Данное приложение решает обычное квадратное уравнение. Все пожелания принимаются автором с огромным вниманием. | Код |
package swt_package;
import org.eclipse.swt.*;
import org.eclipse.swt.widgets.*;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.events.*;
// Roots incapsulation class.
class QuadraticRoots {
// Equation roots variables.
private double x1 = 0, x2 = 0;
// Solution present flag.
private boolean solutionIsPresent = false;
// Constructor for valid results.
public QuadraticRoots(double x1, double x2) {
super();
this.x1 = x1;
this.x2 = x2;
this.solutionIsPresent = true;
}
// Constructor for invalid results.
public QuadraticRoots() {
super();
}
//Methods.
public double getX1() {
return x1;
}
public double getX2() {
return x2;
}
public boolean isSolutionPresent() {
return solutionIsPresent;
}
}
// Window drawing and reaction class.
class ShowQuadraticInterface {
private final Shell shell;
private final Text aValue;
private final Text bValue;
private final Text cValue;
private final Label x1Result;
private final Label x2Result;
public ShowQuadraticInterface() {
Display display = new Display();
this.shell = new Shell(
display, (SWT.BORDER | SWT.CLOSE | SWT.TITLE));
this.shell.setText("Quadratic equation solution project. Copyright VPh.");
// Create Table.
this.shell.setLayout(new GridLayout(2, true));
// Output controls.
createInvintationLabel("Please, enter A,B,C-coefficients of the equation: A*x^2 + B*x + C = 0");
this.aValue = createUserEntryControl("Please, enter 'A' value:", "1");
this.bValue = createUserEntryControl("Please, enter 'B' value:", "3");
this.cValue = createUserEntryControl("Please, enter 'C' value:", "1");
// Output solution button.
Button buttonToSolve = createSolveButton("Solve current Quadratic equation");
// Create button click method.
buttonToSolve.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(SelectionEvent e) {
ShowQuadraticInterface.this.performCalculation();
}
});
// Output results controls.
this.x1Result = createResultLabel();
this.x2Result = createResultLabel();
// Open window.
this.shell.pack();
this.shell.open();
// Waiting window close.
while (!shell.isDisposed()) {
if (!display.readAndDispatch()) {
display.sleep();
}
}
display.dispose();
}
// Methods.
private Label createInvintationLabel(String labelText) {
GridData userHintGrid = new GridData(GridData.HORIZONTAL_ALIGN_CENTER);
userHintGrid.horizontalSpan = 2;
Label userHint = new Label(this.shell, SWT.NONE);
userHint.setLayoutData(userHintGrid);
userHint.setText(labelText);
return userHint;
}
private Text createUserEntryControl(
String labelText,
String initialText) {
new Label(this.shell, SWT.NONE).setText(labelText);
GridData vData = new GridData(GridData.HORIZONTAL_ALIGN_FILL);
vData.horizontalSpan = 1;
Text res = new Text(this.shell, SWT.SINGLE | SWT.BORDER);
res.setLayoutData(vData);
res.setText(initialText);
return res;
}
private Label createResultLabel() {
Label result = new Label(this.shell, SWT.NONE);
GridData lData = new GridData(GridData.FILL_HORIZONTAL);
result.setLayoutData(lData);
return result;
}
private Button createSolveButton(String buttonText) {
Button buttonToSolve = new Button(this.shell, SWT.CENTER);
GridData buttonGrid = new GridData(GridData.HORIZONTAL_ALIGN_FILL);
buttonGrid.horizontalSpan = 2;
buttonToSolve.setLayoutData(buttonGrid);
buttonToSolve.setText(buttonText);
return buttonToSolve;
}
private void drawResults(QuadraticRoots roots) {
if (roots.isSolutionPresent()) {
this.x1Result.setText("x1 = " + String.valueOf(roots.getX1()));
this.x2Result.setText("x2 = " + String.valueOf(roots.getX2()));
} else {
this.x1Result.setText("No real roots.");
}
}
private void clearResults() {
this.x1Result.setText("");
this.x2Result.setText("");
}
//Quadratic solution method.
public QuadraticRoots quadraticSolve(double a, double b, double c) {
double discriminant = b*b - 4*a*c;
if (discriminant < 0)
return new QuadraticRoots();
double x1Root = 0, x2Root = 0;
if (discriminant > 0) {
x1Root = (-b + Math.sqrt(discriminant)) / 2*a;
x2Root = (-b - Math.sqrt(discriminant)) / 2*a;
} else // == 0
x1Root = x2Root = -b / 2*a;
return new QuadraticRoots(x1Root, x2Root);
}
private void performCalculation() {
clearResults();
//Quadratic equation coefficients.
double a = 0, b = 0, c = 0;
try {
a = new Double(aValue.getText()).doubleValue();
b = new Double(bValue.getText()).doubleValue();
c = new Double(cValue.getText()).doubleValue();
} catch (NumberFormatException exp) {
// Input error throw.
this.x1Result.setText("Input Error: " + exp.getLocalizedMessage());
return;
}
//Create solution class for good coefficients.
drawResults(quadraticSolve(a,b,c));
}
}
// Start up application.
public class swt_class {// SWTQuadraticEquationSolverDemo {
public static void main(String[] args) {
ShowQuadraticInterface inputInterface = new ShowQuadraticInterface();
System.out.println("Bye-bye :-)");
}
}
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А вот еще один вариант, который предоставил NotGonnaGetUs| Код |
package swt_package;
class QuadraticRoots { // Roots incapsulation class.
public static final QuadraticRoots ANY_SOLUTION = new QuadraticRoots(Double.NaN);
public static final QuadraticRoots NO_SOLUTION = new QuadraticRoots(Double.NaN);
private double x1, x2; // Equation roots variables.
public QuadraticRoots(double x) { // Constructor for valid results.
this(x, x);
}
public QuadraticRoots(double x1, double x2) { // Constructor for valid results.
this.x1 = x1;
this.x2 = x2;
}
public double getX1() { return x1; }
public double getX2() { return x2; }
public boolean isAny() {
return this == ANY_SOLUTION;
}
public boolean isNotExist() {
return this == NO_SOLUTION;
}
public boolean isExist() {
return !Double.isNaN(x1) && !Double.isNaN(x2);
}
public static QuadraticRoots getSolution(double a, double b, double c) { //get roots of ax^2 + bx + c = 0;
if (a == 0 && b == 0) { //solve c = 0;
if (c != 0) {
return NO_SOLUTION;
} else {
return ANY_SOLUTION;
}
}
if (a == 0) { //solve bx + c = 0;
return new QuadraticRoots(-c / b);
}
double discriminant = b * b - 4 * a * c;
if (discriminant < 0) {
return NO_SOLUTION;
}
double x1, x2;
if (discriminant == 0) {
x1 = x2 = -b / (2 * a);
} else { // discriminant > 0
double d = Math.sqrt(discriminant);
x1 = (-b + d) / (2 * a);
x2 = (-b - d) / (2 * a);
}
return new QuadraticRoots(x1, x2);
}
}
class ShowQuadraticInterface { // Window drawing and reaction class.
private final Shell shell;
private final Text aValue;
private final Text bValue;
private final Text cValue;
private final Label x1Result;
private final Label x2Result;
public ShowQuadraticInterface() {
Display display = new Display();
shell = new Shell(display, (SWT.BORDER | SWT.CLOSE | SWT.TITLE));
shell.setText("Quadratic equation solution project. Copyright VPh.");
shell.setLayout(new GridLayout(2, true)); //Create Table.
GuiBuilder builder = new GuiBuilder(shell);
// Output controls.
builder.createInvintationLabel("Please, enter A,B,C-coefficients of the equation: A*x^2 + B*x + C = 0");
aValue = builder.createUserEntryControl("Please, enter 'A' value:", "1");
bValue = builder.createUserEntryControl("Please, enter 'B' value:", "3");
cValue = builder.createUserEntryControl("Please, enter 'C' value:", "1");
// Output solution button.
builder.createSolveButton("Solve current Quadratic equation").addSelectionListener(new SelectionAdapter() { // Create button click method.
public void widgetSelected(SelectionEvent e) {
performCalculation();
}
});
// Output results controls.
x1Result = builder.createResultLabel();
x2Result = builder.createResultLabel();
// Open window.
shell.pack();
shell.open();
// Waiting window close.
while (!shell.isDisposed()) {
if (!display.readAndDispatch()) {
display.sleep();
}
}
display.dispose();
}
private void performCalculation() {
clearResults();
//Quadratic equation coefficients.
double a, b, c;
try {
a = new Double(aValue.getText()).doubleValue();
b = new Double(bValue.getText()).doubleValue();
c = new Double(cValue.getText()).doubleValue();
} catch (NumberFormatException exp) {
// Input error throw.
x1Result.setText("Input Error: " + exp.getLocalizedMessage());
return;
}
//Create solution class for good coefficients.
drawResults(QuadraticRoots.getSolution(a, b, c));
}
private void drawResults(QuadraticRoots roots) {
if (roots.isNotExist()) {
x1Result.setText("No real roots.");
} else if (roots.isAny()) {
x1Result.setText("x1 = any value");
x2Result.setText("x2 = any value");
} else {
x1Result.setText("x1 = " + String.valueOf(roots.getX1()));
x2Result.setText("x2 = " + String.valueOf(roots.getX2()));
}
}
private void clearResults() {
this.x1Result.setText("");
this.x2Result.setText("");
}
private static class GuiBuilder {
private Shell shell;
GuiBuilder(Shell shell) {
this.shell = shell;
}
Label createInvintationLabel(String labelText) {
GridData userHintGrid = new GridData(GridData.HORIZONTAL_ALIGN_CENTER);
userHintGrid.horizontalSpan = 2;
Label userHint = new Label(shell, SWT.NONE);
userHint.setLayoutData(userHintGrid);
userHint.setText(labelText);
return userHint;
}
Text createUserEntryControl(String labelText,
String initialText) {
new Label(this.shell, SWT.NONE).setText(labelText);
GridData vData = new GridData(GridData.HORIZONTAL_ALIGN_FILL);
vData.horizontalSpan = 1;
Text res = new Text(shell, SWT.SINGLE | SWT.BORDER);
res.setLayoutData(vData);
res.setText(initialText);
return res;
}
Label createResultLabel() {
Label result = new Label(shell, SWT.NONE);
result.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));
return result;
}
Button createSolveButton(String buttonText) {
Button buttonToSolve = new Button(shell, SWT.CENTER);
GridData buttonGrid = new GridData(GridData.HORIZONTAL_ALIGN_FILL);
buttonGrid.horizontalSpan = 2;
buttonToSolve.setLayoutData(buttonGrid);
buttonToSolve.setText(buttonText);
return buttonToSolve;
}
}
}
// Start up application.
public class aaa {// SWTQuadraticEquationSolverDemo {
public static void main(String[] args) {
ShowQuadraticInterface inputInterface = new ShowQuadraticInterface();
System.out.println("Bye-bye :-)");
}
}
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Пример использования SWT в JAVA 
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