全新java初学者实践教程6(Java SE5.0版)
`Tv[DIVW 基本语法3
njputEGX >&}%+r\ >s<^M|S07 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:
ivN&HAxI@ f=WDR m] [font="Times] 1.循环语句[font="Times]:while,do-while,for
0"f\@8r( G;l_|8<t#\ [font="Times]2.分支语句[font="Times]:if-else,switch,
.oeX"6K [font="Times]
oU.R2\Q 3.跳转语句[font="Times] break,continue,label: 和[font="Times]return
zd >t-?g [font="Times]
l4uMG]m 4.异常处理语句[font="Times]:try-catch-finally,throw
(2$p{Uf HK2[]G 实践:
Q o{/@ [font="Times] 1.循环语句
M 0U0;QJ [font="Times] while 语句
ZzJ?L4J5v [font="Times]class While {
|l]XpWV [font="Times]public static void main(String args[]) {
V<T9&8l+: [font="Times]int n = 10;
<h:x= [font="Times]while(n > 0) {
P&*2pX: [font="Times]System.out.println("tick " + n);
@emK1iwm [font="Times]n--;
RwpdRBb [font="Times]}
D$I5z.a [font="Times]}
b?tB(if!I [font="Times]}
j}.\]$J [font="Times] do…while 语句
CDK5 [font="Times] class DoWhile {
>JFO@O5 [font="Times]public static void main(String args[]) {
/} b03 [font="Times]int n = 10;
rrik,qyv6 [font="Times]do {
Nh_Mz;ITuu [font="Times]System.out.println("tick " + n);
B#Vz#y [font="Times]n--;
r{L>
F]Tw [font="Times]} while(n > 0);
4R1<nZ"e~ [font="Times]}
vunHNHltW0 [font="Times]}
jtW!"TOY 二者区别,[font="Times]do…while至少循环一次,而[font="Times]while的表达式要是为[font="Times]flase的话可以一次也不循环。再通俗一点,[font="Times]do…while就算是括号里的是[font="Times]flase,人家最少也能[font="Times]do一次。
S.-TOE [font="Times] for语句
Y[}>CYO [font="Times] class ForTick {
#W4dkCd(pF [font="Times]public static void main(String args[]) {
H4&lb} [font="Times]int n;
w"-Lc4t+ [font="Times]for(n=10; n>0; n--)
/<|%yE&KhJ [font="Times]System.out.println("tick " + n);
U`, 6 * MS [font="Times]}
3q\,$*D. [font="Times]}
KBx6NU?;PO 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。
^:^9l1] 还有啊,[font="Times]for循环的部分可以为空的
=5~jx [font="Times]class ForVar {
FQ<Ju. [font="Times]public static void main(String args[]) {
[+n*~ [font="Times]int i;
o ,AAC [font="Times]boolean done = false;
,St#Vla [font="Times]i = 0;
qNB<T(' [font="Times]for( ; !done; ) {
7:plQ!7^ [font="Times]System.out.println("i is " + i);
$P^q!H4D [font="Times]if(i == 10) done = true;
S2sQOM@ [font="Times]i++;
W$hx,VEy` [font="Times]}
0zmE>/O+ [font="Times]}
]hk [font="Times]}
循环语句的例子下载 p6>Svcc [font="Times] 2.分支语句[font="Times]
;g+N&)n [font="Times] if/else语句
mHdA2 [font="Times]class IfElse {
]%@M>?Ywc [font="Times]public static void main(String args[]) {
v_+{'F [font="Times]int month = 4; // April
.,<1%-R34q [font="Times]String season;
5F)C jQ [font="Times]if(month == 12 || month == 1 || month == 2)
'3/4?wi [font="Times]season = "Winter";
zy/@
WFPE [font="Times]else if(month == 3 || month == 4 || month == 5)
BC&S> #\ [font="Times]season = "Spring";
+Vb.lH[av [font="Times]else if(month == 6 || month == 7 || month == 8)
Gp?a(-K5 [font="Times]season = "Summer";
?+@n3]`0 [font="Times]else if(month == 9 || month == 10 || month == 11)
B+P(M!m3 [font="Times]season = "Autumn";
#A1%gIw<v2 [font="Times]else
P{kur} T [font="Times]season = "Bogus Month";
/M1ob: m [font="Times]System.out.println("April is in the " + season + ".");
j4gF;-m< [font="Times]}
N.,X<G.H [font="Times]}
`i3NG1
v0 [font="Times]//这段程序输出[font="Times]:
q9KHmhUD [font="Times]//April is in the Spring.
fInb[ [font="Times]// 注意[font="Times] “[font="Times]||”是或运算
0L2 F[TN [font="Times] switch语句
ry`Ho8N [font="Times] class Switch {
x-WmMfcz& [font="Times]public static void main(String args[]) {
ak$f"py
x [font="Times]int month = 4;
cOmw?kA*G [font="Times]String season;
n9W(bG o [font="Times]switch (month) {
-`*a'p-= [font="Times]case 12:
V#2+"(7h [font="Times]case 1:
O,{6*[)@ [font="Times]case 2:
GZN ^k+w [font="Times]season = "Winter";
eVjBGJ=2e [font="Times]break;
<=zQ NBtx [font="Times]case 3:
}aa'\8 [font="Times]case 4:
,>bh$| [font="Times]case 5:
SA&Rep^ [font="Times]season = "Spring";
kJ'[K!r [font="Times]break;
:;t:H]
f [font="Times]case 6:
0gW"i&7c [font="Times]case 7:
q6McG HT [font="Times]case 8:
Vz~{UHH6 [font="Times]season = "Summer";
@Q)OGjaq [font="Times]break;
@'#,D!U [font="Times]case 9:
U dT*E: 6 [font="Times]case 10:
%a>&5V [font="Times]case 11:
g1/:Q%R,
[font="Times]season = "Autumn";
l%k\JY- [font="Times]break;
7OcWC-< [font="Times]default:
E:UW#S%A
f [font="Times]season = "Bogus Month";
fiK6@, [font="Times]}
}"nItcp.1 [font="Times]System.out.println("April is in the " + season + ".");
YqhAZp< [font="Times]}
x|/|jzJSX [font="Times]}
分支语句代码下载 >N^Jj:~l $Xv* ,Bq [font="Times]switch语句适合于条件非常多的逻辑
nsu@h 请看上述语句可以混合使用,请看
下载例子