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);
}
}