class lesson2
{
//
/*
*/
/**
*/
public static void main(String[] args)
{
/*int x=0,y;
y=x+3;
System.out.println("Hello" +"world");*/
/*char ch='x';
System.out.println(ch);
byte b=122;
int x=266;
b=(byte)x;
System.out.println(b);
float f=3.5f;*/
//byte b=3;
//b=b-1;
/*int x=9;
{
int x=3;
System.out.println(x);
}
System.out.println(x);
System.out.println(""+'a'+1);
}
*/
/*for(int i=0;i<3;i++)
{
for(int j=0;j<5;j++)
{
System.out.print("*");
}
System.out.println();
}
for(int i=0;i<2;i++)
{
for(int j=0;j<4;j++)
{
System.out.print("*");
}
System.out.println();
}
for(int i=0;i<6;i++)
{
for(int j=0;j<10;j++)
{
System.out.print("*");
}
System.out.println();
}*/
dramRectangle(-3,5);
dramRectangle(2,4);
dramRectangle(6,10);
int x=3,y=5;
int area = getArea(x,y);
System.out.println("3*5="+area);
System.out.println("2*4="+getArea(2,4));
getArea(6,10);
}
static int getArea(int x,int y)
{
/*int sum=x*y;
return sum;*/
return x*y;
}
static void dramRectangle(int x,int y)
{
if(x<=0 || y<=0)
return;
for(int i=0;i<x;i++)
{
for(int j=0;j<y;j++)
{
System.out.print("*");
}
System.out.println();
}
return;
}
}
class lesson22
{
public static void main(String[] args)
{
int x=6;
if(x<3)
{
System.out.println("x<3");
System.out.println("OK");
}
else if(x>=3 && x<8)
System.out.println("x>=3 && x<8");
/*else
{
System.out.println("x>=3");
System.out.println("false");
}*/
int y;
/*if(x>0)
y=x;
else
y=-x;*/
y=x>0?x:-x;
if(x==1)
{
if(y==1)
{
System.out.println("x==1,y==1");
}
else
System.out.println("x!=1,y==1");
}
else if(x>3)
{
if(y==1)
System.out.println("x!=1,y==1");
else
System.out.println("x!=1,y!=1");
}
x=1;
switch(x)
{
case 1:
System.out.println("switch1");
break;
case 2:
System.out.println("switch2");
break;
case 3:
case 4:
System.out.println("3,4");
break;
default:
System.out.println("other");
}
/*do
{
try
{
x=System.in.read();
}catch(Exception e){}
System.out.println(x);
}
while(x!='q');*/
int i=0;
for(;;)
{
if(i>=10)
break;
System.out.println(i);
i++;
}
for(i=0;i<10;i++)
{
if(i%2==0)
continue;
System.out.println(i);
}
}
}
class lesson23
{
public static void main(String[] args)
{
int x[];
x=new int[100];
x=null;
//x[0]=10;
x=new int[]{3,1,2,4};
//java.util.Arrays.sort(x);
int []y=new int[10];
System.arraycopy(x,1,y,5,3);
//System.out.println(x[4]);//数组角标是从0开始的
int sum=0;
System.out.println(x.length);
for(int i=0;i<y.length;i++)
{
System.out.println("y[" +i+"]="+y[i]);
//sum+=x[i];
//数组;两块内顾(栈内存,堆内存),JAVA比较吃内存
//声明数组时,不能指定其长度.
}
int[][] xx=new int[2][3];
xx[0][0]=3;
xx[1][2]=6;
for(int i=0;i<xx.length;i++)
{
for(int j=0;j<xx[i].length;j++)
System.out.println("xx["+i+"]["+j+"]="+xx[i][j]);
}
}
}
