全新java初学者实践教程6(Java SE5.0版)
VvT7v] 基本语法3
VDZOJM)( ]EUQMyR Z[B:6\oQ 我们这个教程侧重的是实践的内容和语言的重点。在[font="Times]java语言中还有很多细节的东西,请参考[font="Times]sun公司的官方培训教程。我们这里不能一一讲述。这节课我们来给大家提供一些程序流程控制的一些例子供大家学习。计算机怎么做事情,是我们教给他的。我们用它解决实际生活中的问题,所以计算机要描述现实生活中的流程。[font="Times]Java语言中提供了[font="Times]4类程序控制语句,来描述流程:
E|jU8qz>P l2YA/9. [font="Times] 1.循环语句[font="Times]:while,do-while,for
,?HM5c{'[Y ) jt?X} [font="Times]2.分支语句[font="Times]:if-else,switch,
|.$7.8g [font="Times]
MOay^{u 3.跳转语句[font="Times] break,continue,label: 和[font="Times]return
NFC/4 [font="Times]
x34GRe!! 4.异常处理语句[font="Times]:try-catch-finally,throw
B|8|f(tsSa / {[p?7x> 实践:
nJ/}b/A{ [font="Times] 1.循环语句
rl&.|;5uH; [font="Times] while 语句
)4.-6F7U? [font="Times]class While {
^FVmP d*1 [font="Times]public static void main(String args[]) {
K4+|K:e [font="Times]int n = 10;
71ab&V il [font="Times]while(n > 0) {
b'z\|jY [font="Times]System.out.println("tick " + n);
XHOS"o$y [font="Times]n--;
`%EcQ}Nr [font="Times]}
*-uzsq.W [font="Times]}
wh2E$b(- [font="Times]}
& JJ*?Dl [font="Times] do…while 语句
_ n1:v~ [font="Times] class DoWhile {
shP}T[< [font="Times]public static void main(String args[]) {
F2ISg' [font="Times]int n = 10;
z#rp8-HUDS [font="Times]do {
OVc)PMp [font="Times]System.out.println("tick " + n);
2-Wy@\ [font="Times]n--;
>oaL -01i [font="Times]} while(n > 0);
o^MoU2c [font="Times]}
3 TTQff [font="Times]}
zSu,S4m_; 二者区别,[font="Times]do…while至少循环一次,而[font="Times]while的表达式要是为[font="Times]flase的话可以一次也不循环。再通俗一点,[font="Times]do…while就算是括号里的是[font="Times]flase,人家最少也能[font="Times]do一次。
wXKt)3dm u [font="Times] for语句
E7_OI7C [font="Times] class ForTick {
'#eT [font="Times]public static void main(String args[]) {
{E7STLQ_% [font="Times]int n;
qmenj [font="Times]for(n=10; n>0; n--)
,A)Z.OWOq [font="Times]System.out.println("tick " + n);
ET 0(/Zz [font="Times]}
-YmIRocx [font="Times]}
jzZ]+'t 与上面那两个的区别,[font="Times]for循环执行的次数是可以在执行之前确定的。通俗一点说吧,看这个例子[font="Times] for(n=10; n>0; n--)就是在括号里的时候,就已经知道要循环[font="Times]10次了。
8OO[Le]1 还有啊,[font="Times]for循环的部分可以为空的
U0srwt97S [font="Times]class ForVar {
&\Lu}t7Ru [font="Times]public static void main(String args[]) {
12_7UWZ" [font="Times]int i;
8G9( )UF. [font="Times]boolean done = false;
0
0|!g"E>$ [font="Times]i = 0;
B7YE+ [font="Times]for( ; !done; ) {
&
9
c^9<F [font="Times]System.out.println("i is " + i);
eH[i<Z [font="Times]if(i == 10) done = true;
x5Fo?E [font="Times]i++;
zA:q/i [font="Times]}
jUgx
;= [font="Times]}
m|t\w|B2 [font="Times]}
循环语句的例子下载 N:S2X+}( [font="Times] 2.分支语句[font="Times]
$|TLt{ K [font="Times] if/else语句
g W9`k,U [font="Times]class IfElse {
R,=8)OI2 [font="Times]public static void main(String args[]) {
q">}3`k [font="Times]int month = 4; // April
mZmEE2h [font="Times]String season;
(/!@
-]1 [font="Times]if(month == 12 || month == 1 || month == 2)
~C>Q+tR8 [font="Times]season = "Winter";
)0"T?Ivp] [font="Times]else if(month == 3 || month == 4 || month == 5)
U@{>+G[ [font="Times]season = "Spring";
o^//|]H3Y [font="Times]else if(month == 6 || month == 7 || month == 8)
F-
u"zox [font="Times]season = "Summer";
\Sv|yQUT [font="Times]else if(month == 9 || month == 10 || month == 11)
W:6#0b"_# [font="Times]season = "Autumn";
25 :v c0 [font="Times]else
-m mQ]'.0 [font="Times]season = "Bogus Month";
kC6Y?g [font="Times]System.out.println("April is in the " + season + ".");
4FZ/~Y1} [font="Times]}
H@~tJ\L [font="Times]}
i~R+g3oi [font="Times]//这段程序输出[font="Times]:
p~""1m01,D [font="Times]//April is in the Spring.
Sm?|,C3V [font="Times]// 注意[font="Times] “[font="Times]||”是或运算
7,V_5M;t [font="Times] switch语句
LU`) [font="Times] class Switch {
w"#rwV& [font="Times]public static void main(String args[]) {
%}Y&qT? [font="Times]int month = 4;
QD%6K=8Q [font="Times]String season;
Q~k|lTf [font="Times]switch (month) {
aNQ(xiskb [font="Times]case 12:
rKdsVW [font="Times]case 1:
k B4Fz [font="Times]case 2:
ZM<UiN [font="Times]season = "Winter";
81(\8#./ [font="Times]break;
sG[qlzR=8 [font="Times]case 3:
J$sp6g>K [font="Times]case 4:
s{V&vRr [font="Times]case 5:
8Q{9AoQ3' [font="Times]season = "Spring";
w'VuC82SZ [font="Times]break;
U5@B7v1 [font="Times]case 6:
\u(Gj]B#" [font="Times]case 7:
v0tFU!Q% [font="Times]case 8:
dLwP7#r [font="Times]season = "Summer";
8*&73cp [font="Times]break;
Gm=&[?} [font="Times]case 9:
l @@pXg3 [font="Times]case 10:
^P/OHuDL [font="Times]case 11:
ZrA*MN [font="Times]season = "Autumn";
(x.qyYEoI [font="Times]break;
Fi\)ka\u [font="Times]default:
NLYf [font="Times]season = "Bogus Month";
x2aG5@<3 [font="Times]}
-f1}N|hy [font="Times]System.out.println("April is in the " + season + ".");
Gl45HyY_ [font="Times]}
I,,SR" [font="Times]}
分支语句代码下载 aRI. &3- 99,=dzm [font="Times]switch语句适合于条件非常多的逻辑
%W| Sl 请看上述语句可以混合使用,请看
下载例子