Java_note

目录Java语法 (2)Java的编译 (2)acm.program Hierarchy(层次) (2)acm.graphics.* (3)GCanvas and GraphicsProgram (3)GObjects (3)Common Methods (3)Interface (4)GLabel (4)Gline (4)GRect, GOval, GArc, GImage (4)GPolygon (5)GCompound (5)Event-driven Programs (6)Mouse Events (6)Keyboard Events (6)Character and String (7)Character Class (7)String (7)acm.util.* (8)Random Generator (8)java.util.* (9)StringTokenizer (9)Java语法Java的编译The Java Interpreter(编译):Source file—Compiler—Class files—Linker—JAR archive(存档) —JVM(Java Virtual Machine)—Run Other class filesacm.program Hierarchy(层次)— ConsoleProgramApplet—Japplet—Program — DialogProgram— GraphicsProgramacm.graphics.*Structure of acm.graphics Package—GCanvas, GPoint, GDimensions, GRectangle, GMath;GObject —GLabel, GRect (GRounfRect, G3DRect), GOval, GLine, GArc, GImage, GPoltgon, GCompound;Interface: GFillable, GResizable, GScalable, GContainer.GCanvas and GraphicsProgramMethods in GCanvas and GraphicsProgramvoid add(object) Adds the object to the canvas at the front of the stackvoid add(object, x, y) Moves the object to (x, y) and then adds it to the canvasvoid remove(object) Removes the object from the canvasvoid removeAll() Removes all objects from the canvasGObject getElementAt(x,y) Returns the frontmost GObject at (x, y), or nullif noneint getWidth() Returns the width in pixels of the entire canvasint getHeight() Returns the height in pixels of the entire canvasvoid setBackground(color) Sets the background color of the canvasMethods are available in GraphicsProgram onlyvoid pause(milliseconds) Pauses the program for the specified time in millisecondsvoid waitForClick() Suspends the program until the user clicks the mouseGObjectsCommon Methodsvoid setLocation(x,y) Resets the location of the object to the specified pointvoid move(dx,dy) Moves the object dx and dy pixels from its current position double getX() Returns the x coordinate of the objectdouble getY() Returns the y coordinate of the objectdouble getWidth() Returns the horizontal width of the object in pixelsdouble getHeight() Returns the vertical height of the object in pixelsboolean contains(x, y) Returns true if the object contains the specified pointvoid setColor(color) Sets the color of the objectColor getColor() Returns the color currently assigned to the objectvoid setVisible(boolean) Sets the visibility flag (false=invisible, true=visible)boolean isVisible() Returns trueif the object is visiblevoid sendToFront() Sends the object to the front of the stacking ordervoid sendToBack() Sends the object to the back of the stacking ordervoid sendForward() Sends the object forward one position in the stacking orderInterfaceGFillable(GRect, GOval, GArc, GPolygon) 填充void setFilled(boolean) Sets the fill state for the object (false=outlined, true=filled)boolean isFilled() Returns the fill state for the objectvoid setFillColor(color) Sets the color used to fill the interior of the objectColor getFillColor() Returns the fill colorGResizable(GOval, GRect, GImage) 重置大小void setSize(width, height) Sets the dimensions of the object as specifiedvoid setBounds(x, y, width, height) Sets the location and dimensions togetherGScalable(GLine, GOval, GRect, GArc, GCompound, GImage, GPolygon,) 对象放缩void scale(sf) Scales both dimensions of the object by sfvoid scale(sx, sy) Scales the object by sx horizontally and sy verticallyGLabelConstructornew GLabel(text, x, y) Creates a label containing the specified text that begins at the point (x, y).Methods specific to the GLabel classvoid object.setFont(“font”) Sets the font used to display the label as specified by the font string. Form "family-style-size" “字体-字形-大小”字形包括PLAIN(普通), BOLD(加粗), ITALIC(斜体), BOLDITALIC.void Object.setLabel(String) Set the content of the labelGlineConstructornew GLine(x0, y0, x1, y1) Creates a line extending from (x0, y0) to (x1, y1).Methods specific to the GLine classvoid object.setEndPoint(x, y) Set the end point of the lineGRect, GOval, GArc, GImageConstructornew GRect(x, y, width, height) Creates a rectangle whose upper left corner is at (x, y) of the specifiedsize.new GOval(x, y, width, height) Creates an oval that fits inside the rectangle with the same dimensions.new GArc(x, y, width, height, start angle, sweep angle) Creates an arc whose upper left corner is at (x, y) of the specified size and from start angle to the end angle by sweep angle.GFillable(GRect, GOval, GArc, GPolygon) 填充void setFilled(boolean) Sets the fill state for the object (false=outlined, true=filled) boolean isFilled() Returns the fill state for the objectvoid setFillColor(color) Sets the color used to fill the interior of the objectColor getFillColor() Returns the fill colorGResizable(GOval, GRect, GImage) 重置大小void setSize(width, height) Sets the dimensions of the object as specifiedvoid setBounds(x, y, width, height) Sets the location and dimensions togetherGScalable(GLine, GOval, GRect, GArc, GCompound, GImage, GPolygon,) 对象放缩void scale(sf) Scales both dimensions of the object by sfvoid scale(sx, sy) Scales the object by sx horizontally and sy verticallyGPolygonCreate an empty Gpolygon objectaddVertex(x, y) (x and y relative to reference point of polygon)addVertex(x, y) or addEdge(dx, dy)Polygon "closed" for youMethods specific to the GPolygon classvoid object.addVertex(x, y) adds a new vertex relative to the reference pointvoid object. addEdge(dx, dy) adds a new vertex relative to the preceding oneGCompoundGCompoundallows for combining several graphics objects so they behave like one GObject.GCompound has a reference point that all objects are added with respect to.public class * extends GCompound通常由构造函数和其他函数组成Event-driven ProgramsWhen users interact with computer, they generate events (e.g., moving/clicking the mouse, typing, etc.) Can respond to events by having listener for events (addMouseListeners() and addKeyListerners())Use Java library the deals with events: import java.awt.event.*;Methods of a listener get called asynchronously when events occur.Mouse Eventsvoid mouseClicked(e) Called when the user clicks the mousevoid mousePressed(e) Called when the mouse button is pressedvoid mouseReleased(e) Called when the mouse button is releasedvoid mouseMoved(e) Called when the user moves the mousevoid mouseDragged(e) Called when the mouse is dragged with the button down// Called on mouse press to record the coordinates of the click */public void mousePressed(MouseEvent e) {last = new GPoint(e.getPoint());gobj = getElementAt(last);}// Called on mouse drag to reposition the objectpublic void mouseDragged(MouseEvent e) {if (gobj != null) {gobj.move(e.getX() - last.getX(), e.getY() - last.getY());last = new GPoint(e.getPoint());}}Keyboard Eventsvoid keyPressed(e) Called when the user presses a keyvoid keyReleased(e) Called when the key comes back upvoid keyTyped(e) Called when the user types (presses and releases) a keyCharacter and StringCharacter ClassMethods in the Character Classstatic boolean isDigit(char ch) Determines if the specified character is a digit.static boolean isLetter(char ch) Determines if the specified character is a letter.static boolean isLetterOrDigit(char ch) Determines if the specified character is a letter or a digit.static boolean isLowerCase(char ch) Determines if the specified character is a lowercase letter.static boolean isUpperCase(char ch) Determines if the specified character is an uppercase letter.static boolean isWhitespace(char ch)Determines if the specified character is whitespace (spaces and tabs).static char toLowerCase(char ch) Converts ch to its lowercase equivalent, if any. If not, chis returned unchanged.static char toUpperCase(char ch) Converts ch to its uppercase equivalent, if any. If not, chis returned unchanged.StringMethods in the String Classint length() Returns the length of the stringchar charAt(int index)Returns the character at the specified index. Note: Strings indexed starting at 0. String substring(int p1, int p2)Returns the substring beginning at p1 and extending up to but not including p2 String substring(int p1)Returns substring beginning at p1and extending through end of string. boolean equals(String s2)Returns true if string s2is equal to the receiver string. This is case sensitive.int compareTo(String s2) Returns integer whose sign indicates how strings compare in lexicographic orderint indexOf(char ch) or int indexOf(String s) Returns index of first occurrence of the character or the string, or -1 if not foundString toLowerCase() orString toUpperCase()Returns a lowercase or uppercase version of the receiver string 注：String赋初值时可以为空，即String str = "";Random Generator/* Private instance variables */private RandomGenerator rgen = RandomGenerator.getInstance()Methods to Generate Random objectint nextInt(int low, int high) Returns a random int between low and high, inclusive.int nextInt(int n) Returns a random int between 0 and n-1double nextDouble(double low,double high)Returns a random doubled in the range low≤d< high.double nextDouble() Returns a random doubled in the range 0 ≤d< 1.boolean nextBoolean() Returns a random boolean value, which is true50 percent of the time.boolean nextBoolean(double p) Returns a random boolean,which is true with probability p, where 0 ≤p≤1.Color nextColor() Returns a random color.StringTokenizerConstructorStringTokenizer tokenizer = new StringTokenizer(line) Creating a tokenizerfor a string lineCommon methods of StringTokenizerboolean hasMoreTokens() If more token in the string, return tureString nextToken() Ruturn a token to an object string。