实践：
1．循环语句
while 语句
class While {
public static void main(String args[])
{
int n = 10;
while(n > 0) {
System.out.println("tick " + n);
n--;
}
}
}
do…while 语句
class DoWhile {
public static void main(String args[])
{
int n = 10;
do {
System.out.println("tick " + n);
n--;
} while(n > 0);
}
}
二者区别，do…while至少循环一次，而while的表达式要是为flase的话可以一次也不循环。再通俗一点，do…while就算是括号里的是flase，人家最少也能do一次。
for语句
class ForTick {
public static void main(String args[])
{
int n;
for(n=10; n>0;
n--)
System.out.println("tick " + n);
}
}
与上面那两个的区别，for循环执行的次数是可以在执行之前确定的。通俗一点说吧，看这个例子 for(n=10; n>0;
n--)就是在括号里的时候，就已经知道要循环10次了。
还有啊，for循环的部分可以为空的
class ForVar {
public static void main(String
args[]) {
int i;
boolean done =
false;
i = 0;
for( ; !done; )
{
System.out.println("i is " +
i);
if(i == 10) done =
true;
i++;
}
}
} 循环语句的例子下载
2．分支语句
if/else语句
class IfElse {
public static void main(String args[])
{
int month = 4; // April
String season;
if(month == 12 || month == 1 || month ==
2)
season =
"Winter";
else if(month == 3 || month == 4 || month ==
5)
season =
"Spring";
else if(month == 6 || month == 7 || month ==
8)
season =
"Summer";
else if(month == 9 || month == 10 || month ==
11)
season =
"Autumn";
else
season = "Bogus
Month";
System.out.println("April is in
the " + season + ".");
}
}
//这段程序输出:
//April is in the Spring.
// 注意 “||”是或运算
switch语句
class Switch {
public static void main(String args[])
{
int month = 4;
String season;
switch (month) {
case 12:
case 1:
case 2:
season = "Winter";
break;
case 3:
case 4:
case 5:
season =
"Spring";
break;
case 6:
case 7:
case 8:
season = "Summer";
break;
case 9:
case 10:
case 11:
season = "Autumn";
break;
default:
season = "Bogus Month";
}
System.out.println("April is in the " + season +
".");
}
} 分支语句代码下载
switch语句适合于条件非常多的逻辑
请看上述语句可以混合使用，请看下载例子
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