全新java初学者实践教程6(Java SE5.0版)
#(*WxVE 基本语法3
I.e' a^5`fA/L, c\4n 7m,y 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:
iVu+ct-iv |/lIasI [font="Times] 1.循环语句[font="Times]:while,do-while,for
^! ZjK-$A< %dT%r=%Y [font="Times]2.分支语句[font="Times]:if-else,switch,
mLY * [font="Times]
<CmsnX 3.跳转语句[font="Times] break,continue,label: 和[font="Times]return
.Um%6a- [font="Times]
W@$p'IBwm 4.异常处理语句[font="Times]:try-catch-finally,throw
(\/HGxv v|,H d 实践:
c)6Y.[). [font="Times] 1.循环语句
q%:Jmi> [font="Times] while 语句
_@prv7e [font="Times]class While {
o>`/,-! [font="Times]public static void main(String args[]) {
j*:pW;)^ [font="Times]int n = 10;
n"K7@[d [font="Times]while(n > 0) {
Z ''P5B; [font="Times]System.out.println("tick " + n);
'HcDl@E [font="Times]n--;
5!ReW39c; [font="Times]}
/?XfVhA:A [font="Times]}
u\.sS|$ [font="Times]}
M<~F>(wxA [font="Times] do…while 语句
NxX1_d [font="Times] class DoWhile {
N[+dX_h [font="Times]public static void main(String args[]) {
Gj_b GqF8} [font="Times]int n = 10;
D[#\Y+N [font="Times]do {
0~1P&Qs<
[font="Times]System.out.println("tick " + n);
YKc{P"'/| [font="Times]n--;
49zp@a [font="Times]} while(n > 0);
T&23Pf 1 [font="Times]}
rzBWk [font="Times]}
Csc2 yI%3 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。
1aT$07G0 [font="Times] for语句
d|NNIf [font="Times] class ForTick {
"DN `@ [font="Times]public static void main(String args[]) {
3CHte*NL= [font="Times]int n;
U; q)01 [font="Times]for(n=10; n>0; n--)
'Lw\nO. [font="Times]System.out.println("tick " + n);
zm .2L [font="Times]}
86I* [font="Times]}
0?h .X=G 与上面那两个的区别,[font="Times]for循环执行的次数是可以在执行之前确定的。通俗一点说吧,看这个例子[font="Times] for(n=10; n>0; n--)就是在括号里的时候,就已经知道要循环[font="Times]10次了。
(_08?cN 还有啊,[font="Times]for循环的部分可以为空的
jw[`_ [font="Times]class ForVar {
O46/[{p+8 [font="Times]public static void main(String args[]) {
vZDQ@\HrC [font="Times]int i;
`cv:p|s [font="Times]boolean done = false;
5UM[Iz [font="Times]i = 0;
>PJ-Z~O'
[font="Times]for( ; !done; ) {
5k(#kyP [font="Times]System.out.println("i is " + i);
fIcv}Y [font="Times]if(i == 10) done = true;
E0pQRGPA [font="Times]i++;
t]o gn( [font="Times]}
l&A` [font="Times]}
E>1USKxn [font="Times]}
循环语句的例子下载 4yM8W\je [font="Times] 2.分支语句[font="Times]
r/T DU[`& [font="Times] if/else语句
WE7l[<b [font="Times]class IfElse {
_#F'rl6' [font="Times]public static void main(String args[]) {
F3'X [font="Times]int month = 4; // April
4>E2G: [font="Times]String season;
t;1NzI$^ [font="Times]if(month == 12 || month == 1 || month == 2)
C(P$,;6 [font="Times]season = "Winter";
~<U3KB [font="Times]else if(month == 3 || month == 4 || month == 5)
t}FMBGo[ [font="Times]season = "Spring";
{L eEnh- [font="Times]else if(month == 6 || month == 7 || month == 8)
m&%b;%,J [font="Times]season = "Summer";
\nyFN [font="Times]else if(month == 9 || month == 10 || month == 11)
s?E: ] [font="Times]season = "Autumn";
Vwqfn4sx?i [font="Times]else
>?'FH +2K [font="Times]season = "Bogus Month";
R)C+wTG; [font="Times]System.out.println("April is in the " + season + ".");
:jX~]1hpmA [font="Times]}
8dhY"& [font="Times]}
1m)/_y~1
k [font="Times]//这段程序输出[font="Times]:
WI,=?~- [font="Times]//April is in the Spring.
Dn3~8 [font="Times]// 注意[font="Times] “[font="Times]||”是或运算
@ih}x [font="Times] switch语句
!T~d5^l! [font="Times] class Switch {
1W
g8jr's [font="Times]public static void main(String args[]) {
$OD5t5eTsM [font="Times]int month = 4;
kt#W~n [font="Times]String season;
h,+=h;! [font="Times]switch (month) {
f.$o|R=v [font="Times]case 12:
D=>^m=?0 [font="Times]case 1:
+;Gl>$ [font="Times]case 2:
{\&"I|dpe [font="Times]season = "Winter";
f)x}_dw% [font="Times]break;
h<.[U
$, [font="Times]case 3:
!q/lgpEi [font="Times]case 4:
[mPdT^h [font="Times]case 5:
`[\phv [font="Times]season = "Spring";
^-!HbbVv [font="Times]break;
"/fs%F [font="Times]case 6:
5!zvoX9 [font="Times]case 7:
\G@6jn1G( [font="Times]case 8:
SA1/U [font="Times]season = "Summer";
"/?qT;<$) [font="Times]break;
sriz
b [font="Times]case 9:
4g9b[y~U [font="Times]case 10:
\ c&)8.r [font="Times]case 11:
<yPHdbF [font="Times]season = "Autumn";
(O2HB-<rY [font="Times]break;
MGzF+ln^U [font="Times]default:
V2,WP [font="Times]season = "Bogus Month";
C#&6p0U [font="Times]}
u&x K>7 [font="Times]System.out.println("April is in the " + season + ".");
;NeP&)Td [font="Times]}
,<^HB+{Wo [font="Times]}
分支语句代码下载 =7Vl{>*1N 0gD0}nH [font="Times]switch语句适合于条件非常多的逻辑
v`BG1&/| 请看上述语句可以混合使用,请看
下载例子