/ C2 @( }5 v \! g( V 0 `% ]2 W2 i. T ; h7 E- k7 Y) E" x. @5 x, g1 N ; B. }; z5 k7 B8 ~8 x& ~* x0 f三、 用数组实现队列1、队列的接口定义 - i' W+ r; I& g/**: n8 d$ Q! }& \2 F/ x
* 定义队列的接口( s9 |- p% a# a% H' v/ p' P$ t0 j
* - v7 @5 ^) h( P* G * @author zhuhuix : s! T% C$ M3 L4 e! m" r * @date 2020-05-01 4 c% u" l& G! ?( r0 c */3 ? z* q0 w5 y% q# g
public interface Queue { 8 y7 ]" Y4 {9 H# R* P" [3 V& S8 W2 a2 Z, g, R' x# d: d
/** 6 P" P& M* @) w4 _ * 获取队列大小: U! M8 M( O( a ~5 S
* @return 队列大小 2 k1 @5 I8 t n4 {4 r */ * C8 t2 {3 X B# Q- u3 Z int getMaxSize();" k! q7 t' k! d5 g* O, O- ~
~4 I* Z8 a' h+ G; Z% w /**( n- z# N! C5 N6 _- X" I# N
* 入队4 ]) i9 N8 {/ ?" s( f3 O: C
* @param object 入队元素 ' r9 {' X+ Z) B8 m2 ?. ~7 @$ f */ 9 ~$ {8 p' M; q# N( {0 i void push(Object object);( C- U/ d8 V4 |9 ]- f' A0 J3 V
3 l+ e1 o5 l0 }6 e /** . b* K9 @1 y+ B * 出队 1 W% k6 C# N+ U0 O) X * @return 出栈元素 5 j2 G+ F) j% p* u$ q */5 a: ?& f0 l; n2 H: `
Object pull();6 r& Z3 q8 Q# h: U; ^
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/** k7 u- W% @9 {; J; U5 Y5 c * 获取元素个数8 Q# Y% Y. g; J7 N* }
* @return 元素个数" x! _- q+ _0 Z/ o
*/ " W( ^" k9 U: F# p int getElementCount();! p( p; ^0 M( x; H
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/**" T" y" A. m: f* \# S
* 获取队头元素0 Y+ Y4 S! L& @3 P% ]
* @return 队头元素 # F: F: |& Z4 k" L T( z( ^ */6 d$ G1 e8 f" y+ W! G" ~3 I3 v
Object getFront();1 w7 c1 Z/ h! d1 d; F9 Z
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* 获取队尾元素& v+ |. z+ d- ~: K
* @return 队尾元素! {% ~: _( Y+ c5 H
*/ % D# J6 \$ h5 b! t9 n" U7 s Object getRear();4 a" X4 n( B3 ]% [# \
$ k4 d/ ]5 i2 C /**3 n* K8 B0 ^" b4 [# L5 a$ Y
* 遍历队列的元素) f+ y5 }# X* i6 d( w3 C
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void traverse();2 l8 T4 i g0 W. e- A, \
} / o/ {# i& ?8 \- t1 Y2、队列的接口实现2 I! _7 `6 V7 b5 j+ [
/** , G. J, s) |; k. W- Q" m * 队列的接口实现 y2 a4 |3 j; d; z5 G( z/ S *" t+ F$ J2 W3 Y
* @author zhuhuix 5 D5 P! y% Q7 D9 E6 t0 U * @date 2020-05-01+ K* t/ a+ |* b: }" M5 ~2 K
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public class QueueImpl implements Queue { # H9 K$ r" R* h% P" r 5 @( z% F/ H( G& q o$ i; Q9 e) L protected Object[] element; + e o; H9 j+ Z# F b$ K& y( L, ?* l1 Y; y7 ~
protected int elementCount;2 x5 O' T& a6 d( ~, T7 V2 u8 j
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//队头% Q) I7 C& A6 Y+ i: }2 Q' S
private int front; % J. V$ F& G# ?# F0 V( q- N+ B- r, \- m2 B5 q- i
//队尾 $ @+ k+ e" Q: }; o: r9 o v. t private int rear; # K; ]: y- G1 u) L/ |. H3 Q / O1 O: E) q4 I ~ private int defaultSize = 16;5 ]# _. b5 r/ \: P# m5 f0 ]1 `; N: J
8 V- m- \. O+ n: y. c8 |( F! p" G private int maxSize; 2 A e2 }6 K- R* @9 N+ P( L; r3 Z" H9 n1 J( x- t9 O
QueueImpl() {* a7 V; J2 H, v( f |* B
element = new Object[defaultSize];4 [( Y% k" m# F3 N; U& H3 [ J
maxSize = defaultSize; : c/ c0 x$ }$ ?% C front = 0;6 [ ^" ~9 n1 K
rear = -1;$ }% G, l, h \4 C+ v4 B ?2 L
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QueueImpl(int size) {# d( o" f1 j" |% g5 p) p- \* i
element = new Object[size]; $ |1 |2 b' ~: Z3 j maxSize = size; / A/ d1 F) a# M$ ?) \8 {8 d7 K1 a front = 0;$ G0 F/ O2 ^" E- k
rear = -1; * Z/ h! V$ C& T }( z7 v8 e3 ~. A' C
9 u8 i* e1 i# ] @Override V- p6 Q7 K: a; N* I: Z public int getMaxSize() {7 U0 B: C3 S1 j1 k+ ]
return maxSize; ) g0 u7 v u d+ l6 N, w" N/ m+ C' B }' T* r+ [" A h5 F0 G
4 l# J+ t5 e& F) z$ g; f" J @Override - f. a# F9 O' p6 I9 r: ? public void push(Object object) { " B: F, S0 b0 E //如果元素个数已经达到数组的最大个数,则进行扩容 % N8 ^9 b/ \* L: x if (elementCount == maxSize) {* v9 x# Y h/ Z6 W4 x7 @
throw new ArrayIndexOutOfBoundsException("队列已满,请先进行出队"); " ]% z4 u" @! {9 I } ' p6 I S- l2 ?3 `+ i8 W( e" y element[++rear] = object; v8 A8 q# K3 y# I6 U7 \9 @, b
if (rear == element.length) { ! E. n3 Q$ O( B; l* w2 ^$ e rear = -1;7 t1 w6 _) x* ^* K+ J
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elementCount++; / \5 c1 w$ C! \" \- ?& b }+ y; z+ k$ p/ v. ]
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@Override/ m! ^* @/ [" ?8 X
public Object pull() {8 r- f1 J/ [6 d N' K' h- M7 {
if (elementCount == 0) { / @" n& y) m8 `1 u' V, h8 }. B+ \( w throw new ArrayIndexOutOfBoundsException("队列中无元素");# |- F: T: N9 q l& J" R
} ! A5 E9 U% }% e' f* m& K Object object = element[front];9 {/ u" [: A) E- G% |( ^
element[front] = null;6 C7 \9 n) C5 N6 U9 {& R
front++;# ?+ k& t" N8 @
elementCount--;1 ?( D: F* p7 }5 H0 I* h# R8 L
//队列清空,队头队尾恢复初始值. J: Q! m5 e1 C! R. K$ H% \! C
if (elementCount == 0) { 9 A: o! z0 h c' w% w front = 0;/ p1 M! \/ R( U, C9 ^9 T" c" D
rear = -1;. g3 s0 }5 a% z
} ; _; u6 D2 z8 |" ?" h% P, f return object;+ |4 ^$ [- [, S! y v- `1 q* |! y
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6 \7 o! Y3 S& x7 y% ]0 |% B' a: a0 S @Override 4 O' t1 j; u8 w( _5 D public int getElementCount() { . O$ J% H/ U) i8 m; K" { return elementCount;8 b6 c& v/ p* ^. E3 t
} 3 {5 l# f9 x! X: U' i) ~ % o6 O9 c; J, j- L2 y7 t @Override |. e5 F( o& l6 z8 i: `
public Object getFront() { % M) H/ @9 T& F- Z3 Z* v if (elementCount == 0) {' `9 Q; Z" M. g
System.out.print("队头无元素"); 4 w1 \7 y7 B! k1 R- v5 \ return null; ' I; N8 h' x* N% r }3 T# V5 v7 D+ Z) V
return element[front];3 L4 Z& X: B n& F5 G+ x
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@Override 9 t7 _" @" u* I public Object getRear() { 9 ~1 l9 k$ Q' ]4 e1 |. U" }& o if (elementCount == 0) { - y$ a9 [% `' J4 ` t System.out.print("队尾无元素"); - }- t+ l! s5 g$ K+ N! C return null; : }+ ?1 S5 T5 l. l: [ }+ P5 l. C' G/ Z7 p) \9 J1 ?) o8 o
return element[rear];0 ]; M4 f5 P2 V! {1 W- y
} ( D9 A: r9 ]: D3 `1 ^# M0 P E; R2 V, E; W. w4 P# a2 [+ e; R \
@Override0 p Q% M/ ?2 e0 C: |
public void traverse() {4 f; Q7 j8 V4 z% I! U5 S2 N
if (elementCount == 0) { ( K3 ^+ M8 Y" ~& A* b# J' { return; : y* f% k% ^$ @7 ^" L9 p. I7 d } : A& ^5 {1 M* C% | for (int i = front; i <= rear; i++) { ! o; y0 D. X) M; \5 J/ O, m System.out.print(element + ",");2 v% L0 A, M4 x( Q9 v" g
} 4 I* w' a5 N( ~( h7 a! P9 B System.out.println(); 5 P) i. ^4 ^& O2 g( Y' ?* m }5 X2 \% G3 ~5 u0 F o: m, [
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) _# Z7 t, u+ B1 E1 s4 L$ F6 p# j1 e9 `5 c. [5 T' @! x$ a' v 3、队列的测试 5 w2 k0 l4 j5 V; rpublic class QueueTest { " Q8 Y7 h, i+ M G- z; B public static void main(String[] args) {7 Y7 C" |; z9 n6 \$ D
Queue queue = new QueueImpl(); * K s e( h! C9 D ' q. V ?- ~; U6 ^ //获取队列大小 4 Z8 o% q4 f6 v. _0 W System.out.println("队列中最大可放置元素:" + queue.getMaxSize());% b* n0 _% ?. }) x& ^
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//第一次入队列:压入1-15$ \8 m, i! [; d! j1 c; |
for (int i = 0; i < 16; i++) { 7 P& c/ K( k% T" T! L: p4 i3 X queue.push(i);" h" K. C6 I) I; u c! S* Y# \
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System.out.println("第一次入队后元素个数为:" + queue.getElementCount()); 7 Z x! l" `, g3 i queue.traverse();# ]2 g: u. \3 Y) y, g `
System.out.println("队头:"+queue.getFront()+" 队尾:"+queue.getRear()); 1 S6 {: \( r4 o" a! L3 c& C9 F5 m& T, f0 W) z- r$ `
//第一次出队:取出0-15 & y' W4 x6 U3 `3 n. n for (int i = 0; i < 16; i++) {- B* ?: y6 d. y) O/ F ?( G( C1 |
queue.pull();& O5 D% F. m" J f
} 4 @7 _$ f8 `% q% d7 Y5 p/ e System.out.println("第一次出队后元素个数为:" + queue.getElementCount());$ f' b$ _7 p5 p3 }
queue.traverse();% D+ f/ y5 W) ]; x$ O
System.out.println("队头:"+queue.getFront()+" 队尾:"+queue.getRear()); ! W6 U: d( ]) d + o8 l5 k% q7 d/ v& G% W2 G& o0 W5 b
//第二次入队列:压入16,31& j. a1 S/ \' U
for (int i = 16; i < 32; i++) { ) h4 z' I% u7 X9 g7 n8 `3 W queue.push(i);" N' a& C4 t3 \
} + W9 k1 Y; m$ _8 J( K) m9 ^) ] System.out.println("第二次入队后元素个数为:" + queue.getElementCount());2 J! g$ t" m3 l$ h" _
queue.traverse(); \# B) \ ~- I9 z4 ~) l2 g7 n
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//第二次出队:取出16-31 ' ]/ ]' Z0 p" ~" {6 ?6 z for (int i = 0; i < 16; i++) {" C E- P1 y9 X8 O
queue.pull(); ! F9 j+ Q4 t6 I% C, a9 n }2 N+ b+ }2 p# U
System.out.println("第二次出队后元素个数为:" + queue.getElementCount());6 q: R' p: B# ]: D: n
queue.traverse();; Q1 w% a- `( b$ X2 @" U
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//空队列出队报错 m" a" e, ]& g8 }. w3 V! G
queue.pull();( z' V) x- \& I V# b$ V$ c( n
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