《JAVA语言的科学与艺术》学习笔记01

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2.1 HelloProgram.java

import acm.graphics.*;import acm.program.*;public class HelloProgram extends GraphicsProgram {public void run(){add(new GLabel("hello,world",100,75)) ;}}

java原点是左上角而不是左下角

2.4 Add2Integers.java

import acm.program.*;public class Add2Integers extends ConsoleProgram {public void run() {println("This program adds two intergers.") ;int n1 =readInt("Enter n1: ") ;int n2 =readInt("Enter n2: ") ;int total =n1 +n2 ;println("The total is "+total+".");}}

println方法,run方法,readInt方法都是ConsoleProgram类中的方法

2.5 Add2Doubles.java

import acm.program.*;public class Add2Doubles extends ConsoleProgram {public void run(){println("This program adds two intergers.");double n1 =readDouble("Enter n1: ") ;double n2 =readDouble("Enter n2: ") ;double total = n1 +n2 ;println("The total is "+total+".");}}

2.13 GRectExample.java

import acm.graphics.*; import acm.program.*; import java.awt.*;  public class GRectExample extends GraphicsProgram {public void run(){GRect rect = new GRect(100,50,125,60);rect.setFilled(true);rect.setColor(Color.RED);add(rect);}}

2.17 GRectPlusGOval.java

import acm.program.*;import acm.graphics.*;import java.awt.*;public class GRectPlusGOval extends GraphicsProgram{public void run(){GRect rect = new GRect(100,50,125,60) ;rect.setFilled(true);rect.setColor(Color.RED); add(rect);GOval oval = new GOval(100,50,125,60) ;oval.setFilled(true);oval.setFillColor(Color.GREEN); add(oval);}}

2.19 TicTacToBoard.java

import acm.graphics.*;import acm.program.*;public class TicTacToBoard extends  GraphicsProgram {public void run(){add(new GLine(30,60,120,60)) ;add(new GLine(30,90,120,90)) ;add(new GLine(60,30,60,120)) ;add(new GLine(90,30,90,120)) ;}}

2.9 编程练习

2.9.1 HelloProgram.java

import acm.graphics.*;import acm.program.*;public class HelloProgram extends GraphicsProgram {public void run(){add(new GLabel("I Love Java",100,75)) ;add(new GLabel("chensi",120,100)) ;}}

2.9.2 MyProgram.java

/* *File: MyProgram.java *输入2个浮点数，求均值，然后打印均值 */import acm.program.*;public class MyProgram extends ConsoleProgram {public void run(){double b =readDouble("Enter b: ");double h =readDouble("Enter h: ");double a =(b+h)/2 ;println("a="+a);}}

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