[java] How can I get screen resolution in java?

How can one get the screen resolution (width x height) in pixels?

I am using a JFrame and the java swing methods.

Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
double width = screenSize.getWidth();
double height = screenSize.getHeight();
framemain.setSize((int)width,(int)height);
framemain.setResizable(true);
framemain.setExtendedState(JFrame.MAXIMIZED_BOTH);

This code will enumerate the graphics devices on the system (if multiple monitors are installed), and you can use that information to determine monitor affinity or automatic placement (some systems use a little side monitor for real-time displays while an app is running in the background, and such a monitor can be identified by size, screen colors, etc.):

// Test if each monitor will support my app's window
// Iterate through each monitor and see what size each is
GraphicsEnvironment ge      = GraphicsEnvironment.getLocalGraphicsEnvironment();
GraphicsDevice[]    gs      = ge.getScreenDevices();
Dimension           mySize  = new Dimension(myWidth, myHeight);
Dimension           maxSize = new Dimension(minRequiredWidth, minRequiredHeight);
for (int i = 0; i < gs.length; i++)
{
    DisplayMode dm = gs[i].getDisplayMode();
    if (dm.getWidth() > maxSize.getWidth() && dm.getHeight() > maxSize.getHeight())
    {   // Update the max size found on this monitor
        maxSize.setSize(dm.getWidth(), dm.getHeight());
    }

    // Do test if it will work here
}

This call will give you the information you want.

Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();

This is the resolution of the screen that the given component is currently assigned (something like most part of the root window is visible on that screen).

public Rectangle getCurrentScreenBounds(Component component) {
    return component.getGraphicsConfiguration().getBounds();
}

Usage:

Rectangle currentScreen = getCurrentScreenBounds(frameOrWhateverComponent);
int currentScreenWidth = currentScreen.width // current screen width
int currentScreenHeight = currentScreen.height // current screen height
// absolute coordinate of current screen > 0 if left of this screen are further screens
int xOfCurrentScreen = currentScreen.x

If you want to respect toolbars, etc. you'll need to calculate with this, too:

GraphicsConfiguration gc = component.getGraphicsConfiguration();
Insets screenInsets = Toolkit.getDefaultToolkit().getScreenInsets(gc);

Here's some functional code (Java 8) which returns the x position of the right most edge of the right most screen. If no screens are found, then it returns 0.

  GraphicsDevice devices[];

  devices = GraphicsEnvironment.
     getLocalGraphicsEnvironment().
     getScreenDevices();

  return Stream.
     of(devices).
     map(GraphicsDevice::getDefaultConfiguration).
     map(GraphicsConfiguration::getBounds).
     mapToInt(bounds -> bounds.x + bounds.width).
     max().
     orElse(0);

Here are links to the JavaDoc.

GraphicsEnvironment.getLocalGraphicsEnvironment()
GraphicsEnvironment.getScreenDevices()
GraphicsDevice.getDefaultConfiguration()
GraphicsConfiguration.getBounds()

int resolution =Toolkit.getDefaultToolkit().getScreenResolution();

System.out.println(resolution);

int screenResolution = Toolkit.getDefaultToolkit().getScreenResolution();
System.out.println(""+screenResolution);

These three functions return the screen size in Java. This code accounts for multi-monitor setups and task bars. The included functions are: getScreenInsets(), getScreenWorkingArea(), and getScreenTotalArea().

Code:

/**
 * getScreenInsets, This returns the insets of the screen, which are defined by any task bars
 * that have been set up by the user. This function accounts for multi-monitor setups. If a
 * window is supplied, then the the monitor that contains the window will be used. If a window
 * is not supplied, then the primary monitor will be used.
 */
static public Insets getScreenInsets(Window windowOrNull) {
    Insets insets;
    if (windowOrNull == null) {
        insets = Toolkit.getDefaultToolkit().getScreenInsets(GraphicsEnvironment
                .getLocalGraphicsEnvironment().getDefaultScreenDevice()
                .getDefaultConfiguration());
    } else {
        insets = windowOrNull.getToolkit().getScreenInsets(
                windowOrNull.getGraphicsConfiguration());
    }
    return insets;
}

/**
 * getScreenWorkingArea, This returns the working area of the screen. (The working area excludes
 * any task bars.) This function accounts for multi-monitor setups. If a window is supplied,
 * then the the monitor that contains the window will be used. If a window is not supplied, then
 * the primary monitor will be used.
 */
static public Rectangle getScreenWorkingArea(Window windowOrNull) {
    Insets insets;
    Rectangle bounds;
    if (windowOrNull == null) {
        GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
        insets = Toolkit.getDefaultToolkit().getScreenInsets(ge.getDefaultScreenDevice()
                .getDefaultConfiguration());
        bounds = ge.getDefaultScreenDevice().getDefaultConfiguration().getBounds();
    } else {
        GraphicsConfiguration gc = windowOrNull.getGraphicsConfiguration();
        insets = windowOrNull.getToolkit().getScreenInsets(gc);
        bounds = gc.getBounds();
    }
    bounds.x += insets.left;
    bounds.y += insets.top;
    bounds.width -= (insets.left + insets.right);
    bounds.height -= (insets.top + insets.bottom);
    return bounds;
}

/**
 * getScreenTotalArea, This returns the total area of the screen. (The total area includes any
 * task bars.) This function accounts for multi-monitor setups. If a window is supplied, then
 * the the monitor that contains the window will be used. If a window is not supplied, then the
 * primary monitor will be used.
 */
static public Rectangle getScreenTotalArea(Window windowOrNull) {
    Rectangle bounds;
    if (windowOrNull == null) {
        GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
        bounds = ge.getDefaultScreenDevice().getDefaultConfiguration().getBounds();
    } else {
        GraphicsConfiguration gc = windowOrNull.getGraphicsConfiguration();
        bounds = gc.getBounds();
    }
    return bounds;
}

Here is a snippet of code I often use. It returns the full available screen area (even on multi-monitor setups) while retaining the native monitor positions.

public static Rectangle getMaximumScreenBounds() {
    int minx=0, miny=0, maxx=0, maxy=0;
    GraphicsEnvironment environment = GraphicsEnvironment.getLocalGraphicsEnvironment();
    for(GraphicsDevice device : environment.getScreenDevices()){
        Rectangle bounds = device.getDefaultConfiguration().getBounds();
        minx = Math.min(minx, bounds.x);
        miny = Math.min(miny, bounds.y);
        maxx = Math.max(maxx,  bounds.x+bounds.width);
        maxy = Math.max(maxy, bounds.y+bounds.height);
    }
    return new Rectangle(minx, miny, maxx-minx, maxy-miny);
}

On a computer with two full-HD monitors, where the left one is set as the main monitor (in Windows settings), the function returns

java.awt.Rectangle[x=0,y=0,width=3840,height=1080]

On the same setup, but with the right monitor set as the main monitor, the function returns

java.awt.Rectangle[x=-1920,y=0,width=3840,height=1080]