Java使用LinkedList来模拟一个队列(先进先出的特性)

import java.util.LinkedList;

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public class Demo01 {

private LinkedListObject linkedList;

public Demo01() {

linkedList = new LinkedListObject();

}

public void put(Object object) {

linkedList.add(object);

}

public Object get() {

Object object = null;

if (linkedList.size() != 0) {

object = linkedList.get(0);

linkedList.remove(0);

}

return object;

}

public boolean isEmpty() {

if (linkedList.size() != 0) {

return true;

} else {

return false;

}

}

public static void main(String[] args) {

Demo01 demo01 = new Demo01();

demo01.put("1");

demo01.put("2");

System.out.println(demo01.get());

System.out.println(demo01.get());

System.out.println(demo01.isEmpty());

}

}

结果：

1

2

false

java编程 设计队列类。(先进先出)

import java.util.Vector;

@SuppressWarnings({ "unchecked", "serial" })

public class Stat extends Vector {

public void push(Object x) {

super.add(x); // 向队尾添加组件

}

public Object pop() { // 队首元素出队(从队列删除)

Object x = super.elementAt(0); // 返回指定索引处的组件

super.removeElementAt(0); // 删除指定索引处的组件

return x;

}

public void remove() {

super.removeAllElements(); // removeAllElements()移除全部组件，并将其大小设置为零

}

public static void main(String[] args) throws java.io.IOException {

Stat s = new Stat();

s.push("123adfasf123");

s.push(123123132);

System.out.println(s.pop());

System.out.println(s.pop());

}

}

优先级调度算法如何用JAVA实现

没java的 发段源代码给你 有兴趣自己慢慢理解

#include time.h

#include dos.h

#include math.h

#include conio.h

#include stdio.h

#include stdlib.h

#include time.h

#include graphics.h

#define ESC 0x1b

#define ENTER 0x0d

#define TRUE 1

#define FALSE 0

/*每隔TIME秒就变换一次优先级*/

#define TIME 5

/*数据结构*/

/****************************************************************/

enum _Status/*进程状态枚举*/

{

READY =0,/*就绪*/

RUN,/*执行中*/

SUSPEND,/*挂起*/

};

typedef enum _Status Status;

/****************************************************************/

struct _Pcb/*进程结构*/

{

int PID;/*进程ID，ID为负数的进程为系统后备队列的作业*/

int Time;/*进程运行需要的时间*/

int Prior;/*进程的优先级，越大越优先*/

Status Sts;/*状态*/

struct _Pcb *Next;/*指向本进程队列中下个进程的PCB*/

};

typedef struct _Pcb PCB;

/****************************************************************/

struct _Batch/*多道处理中的道结构*/

{

PCB *pcb;/*该道当前正在处理的进程*/

struct _Batch *Next;/*下一道*/

};

typedef struct _Batch Batch;

/****************************************************************/

/*多道系统相关全局变量*/

PCB *ProcQueue = NULL;/*进程链表，按优先级从大到小排列*/

Batch *BatchQueue = NULL;/*系统多道链表*/

/****************************************************************/

/*动态优先权抢占式调度算法及相关函数声明*/

/****************************************************************/

int InitBatchs(int n);/*初始化多道系统，n为道数*/

int InsertProc(int prior, int time);/*向进程链表中按优先级大小插入一个新进程*/

int InsertIDLE();/*向进程队列中加入后备进程，当系统空闲时将被调入*/

int SortProcQueue();/*将进程链表按优先级从大到小排列*/

int AddBatch();/*增加系统道数*/

int DeleteBatch();/*减少系统道数*/

int UnSuspendProc(int id);/*解除ID为id的进程的挂起状态*/

int UpdateBatchs();/*多道系统根据进程链表进行更新，并将执行完毕的进程删除*/

int PassSeconds(int n);/*系统经过n秒后计算数据并进行优先级调度*/

/****************************************************************/

/*各函数的定义*/

/****************************************************************/

int InitBatchs(int n)

{

int i;

for (i=0; in; ++i)

{

AddBatch();

}

return (UpdateBatchs());

}

int InsertProc(int prior, int time)

{

static int sysid = 0;/*该系统已经加入过多少进程，此值将是新进程的ID*/

PCB *last,*now,*pcb;

pcb = (PCB*)malloc(sizeof(PCB));

if (pcb == NULL) return FALSE;

pcb-Prior = prior;

pcb-Time = time;

pcb-PID = (++sysid);

pcb-Sts = READY;

if (ProcQueue == NULL)/*如果进程队列为空*/

{

ProcQueue = pcb;

pcb-Next = NULL;

return TRUE;

}

last = ProcQueue;

now = last-Next;

if (pcb-Prior last-Prior)/*pcb将排在队头*/

{

pcb-Next = ProcQueue;

ProcQueue = pcb;

return TRUE;

}

while ((now != NULL) (pcb-Prior now-Prior))/*寻找插入位置*/

{

last = now;

now = last-Next;

}

last-Next = pcb;

pcb-Next = now;

return TRUE;

}

int InsertIDLE()

{

PCB *now = ProcQueue;

PCB *idle = (PCB*)malloc(sizeof(PCB));

if (idle == NULL) return FALSE;

idle-PID = -1;

idle-Prior = -1;

idle-Sts = SUSPEND;

idle-Time = -1;

idle-Next = NULL;

if (ProcQueue == NULL)

{

ProcQueue = idle;

return TRUE;

}

while(now-Next != NULL)

{

now = now-Next;

}

now-Next = idle;

return TRUE;

}

int SortProcQueue()

{ /*冒泡排序*/

PCB *last, *now;

int b = FALSE;/*上次遍历是否无交换产生*/

if (ProcQueue==NULL || ProcQueue-Next==NULL)/*如果链表中无进程或只有一个进程*/

return FALSE;

while (!b)

{

b = TRUE;

last=ProcQueue;

now=last-Next;

if (last-Prior now-Prior)

{

ProcQueue = now;

last-Next = now-Next;

now-Next = last;

b = FALSE;

last = ProcQueue;

now = last-Next;

}

while (now-Next!=NULL)

{

if ((now-Prior)(now-Next-Prior))

{

last-Next = now-Next;

now-Next = now-Next-Next;

last-Next-Next = now;

b = FALSE;

}

else

last = last-Next;

now = last-Next;

}

}

return TRUE;

}

int AddBatch()

{

Batch *bt = (Batch*)malloc(sizeof(Batch));

if (bt==NULL) return FALSE;

bt-Next = BatchQueue;

BatchQueue = bt;

bt-pcb = NULL;

return (InsertIDLE());

}

int DeleteBatch()

{

Batch *bt = BatchQueue;

PCB *last, *now;

if (BatchQueue==NULL || BatchQueue-Next==NULL)/*如果只剩最后一道则不删除*/

return FALSE;

if (ProcQueue==NULL || ProcQueue-Next==NULL)/*如果只有最后一个后备空闲进程*/

return FALSE;/**/

last = ProcQueue;

now = last-Next;

while (now-Next != NULL)/*查找到最后一个进程，该进程必定是后备空闲进程*/

{

last = now;

now = last-Next;

}

if (now==NULL || now-PID=0)/*未查找到后备进程*/

return FALSE;/**/

free(now);

last-Next = NULL;

BatchQueue = BatchQueue-Next;

free(bt);

return TRUE;

}

int UnSuspendProc(int id)

{

PCB *now = ProcQueue;

if (ProcQueue==NULL) return FALSE;

while (now != NULL)

{

if (now-PID == id)

{

now-Sts = READY;

return TRUE;

}

}

return FALSE;

}

int UpdateBatchs()

{

Batch *bt = BatchQueue;

PCB *last = ProcQueue, *now;

while (bt != NULL)

{

bt-pcb = NULL;

bt = bt-Next;

}

if (ProcQueue == NULL) return TRUE;

while (last-Sts==RUN last-PID=0 last-Time=0)

{

ProcQueue = ProcQueue-Next;

free(last);

last = ProcQueue;

}

now = last-Next;

while (now != NULL)

{

if (now-Sts==RUN now-PID=0 now-Time=0)/*如果该进程是运行中的一般进程并已执行完毕*/

{

last-Next = now-Next;

free(now);

}

else

last = last-Next;

now = last-Next;

}

bt = BatchQueue;

now = ProcQueue;

while (bt != NULL now != NULL)

{

bt-pcb = now;

now-Sts = RUN;

bt = bt-Next;

now = now-Next;

}

while (now != NULL)

{

if (now-Sts == RUN)

{

now-Sts = SUSPEND;

}

now = now-Next;

}

return TRUE;

}

int PassSeconds(int n)

{

static int time = 0;

int i=0, ProcEnd = FALSE;

PCB *pcb = ProcQueue;

Batch *bt = BatchQueue;

if (bt == NULL) return FALSE;

time += n;

if (time=TIME)

{

i = time/TIME;/*经过多少时间段*/

time = time%TIME;

}

while (bt != NULL)/*更新进程运行时间*/

{

if (bt-pcb-PID=0)

{

bt-pcb-Time -= n;

if (bt-pcb-Time = 0)/*进程结束*/

{

ProcEnd = TRUE;

}

}

bt = bt-Next;

}

if (i 0)

{

while (pcb != NULL)/*更新进程优先权（动态优先权）*/

{

if (pcb-Sts == RUN pcb-PID=0)/*运行的进程优先权降低*/

{

pcb-Prior -= i;

if (pcb-Prior 0)

pcb-Prior = 0;

}

else if (pcb-Sts == SUSPEND pcb-PID=0)/*挂起的进程优先权升高*/

pcb-Prior += i;

pcb = pcb-Next;

}

}

if (i0)

SortProcQueue();/*如果优先级有变动则重新排序*/

if (ProcEnd || i0)

{

UpdateBatchs();/*更新多道进程*/

}

return TRUE;

}

/****************************************************************/

/*图形界面相关函数*/

/****************************************************************/

/*表格的单位宽度和高度*/

#define WIDTH 64

#define HEIGHT 12

void *black=NULL;/*背景色方格，使用它擦出表格中的图形*/

int InitGraph()/*初始化图形界面*/

{

int GraphDriver; /* The Graphics device driver */

int GraphMode; /* The Graphics mode value */

int ErrorCode;

GraphDriver = DETECT; /* Request auto-detection */

initgraph( GraphDriver, GraphMode, "" );

ErrorCode = graphresult(); /* Read result of initialization*/

if( ErrorCode != grOk )

{ /* Error occured during init */

printf(" Graphics System Error: %s\n", grapherrormsg( ErrorCode ) );

getch();

return FALSE;

}

cleardevice();

black = (void*)malloc(imagesize(1,1,WIDTH-1,HEIGHT-1));

getimage(1,1,WIDTH-1,HEIGHT-1,black);

DrawFrame();

DrawData();

return TRUE;

}

int DrawFrame()/*画边框和表头*/

{

settextjustify(CENTER_TEXT, CENTER_TEXT);

gprintf(320, HEIGHT/2-1, "Multi-Batch System Emulation");

settextjustify(LEFT_TEXT, TOP_TEXT);

moveto(0,HEIGHT);

lineto(0,479);

lineto(639,479);

lineto(639,HEIGHT);

lineto(0,HEIGHT);

line(WIDTH*4,HEIGHT,WIDTH*4,479);

line(WIDTH*7,HEIGHT,WIDTH*7,479);

line(0,HEIGHT*2,639,HEIGHT*2);

line(0,HEIGHT*3,639,HEIGHT*3);

gprintf(HEIGHT*0+2,HEIGHT*1+2,"System Batchs");/*系统多道列表头*/

gprintf(HEIGHT*0+2,HEIGHT*2+2,"Batch");

gprintf(WIDTH*1+2,HEIGHT*2+2,"ProcID");

gprintf(WIDTH*2+2,HEIGHT*2+2,"Time");

gprintf(WIDTH*3+2,HEIGHT*2+2,"Prior");

gprintf(WIDTH*4+2,HEIGHT*1+2,"Suspended Processes");/*挂起队列列表头*/

gprintf(WIDTH*4+2,HEIGHT*2+2,"ProcID");

gprintf(WIDTH*5+2,HEIGHT*2+2,"Time");

gprintf(WIDTH*6+2,HEIGHT*2+2,"Prior");

gprintf(WIDTH*7+2,HEIGHT*1+2,"Ready Processes");/*就绪队列列表头*/

gprintf(WIDTH*7+2,HEIGHT*2+2,"ProcID");

gprintf(WIDTH*8+2,HEIGHT*2+2,"Time");

gprintf(WIDTH*9+2,HEIGHT*2+2,"Prior");

}

int DrawData()/*绘制系统数据*/

{

int numRun=0, numSus=0, numRed=0;/*运行挂起和就绪的进程各有多少*/

PCB* now = ProcQueue;

int x=0, y=0;

while (now != NULL)

{

switch(now-Sts)

{

case RUN:

x = WIDTH*1;

y = HEIGHT*(3+(numRun++));

break;

case SUSPEND:

x = WIDTH*4;

y = HEIGHT*(3+(numSus++));

break;

case READY:

x = WIDTH*7;

y = HEIGHT*(3+(numRed++));

break;

}

if (now-Sts==RUN)/*该进程为正在运行的进程*/

{

putimage(x-WIDTH+1,y+1,black,COPY_PUT);

gprintf(x-WIDTH+2,y+2,"%d",numRun);

}

if (now-PID=0)/*该进程不是后备进程*/

{

putimage(x+1,y+1,black,COPY_PUT);

gprintf(x+2,y+2,"%d",now-PID);

putimage(x+1+WIDTH,y+1,black,COPY_PUT);

gprintf(x+WIDTH+2,y+2,"%d",now-Time);

putimage(x+1+WIDTH*2,y+1,black,COPY_PUT);

gprintf(x+WIDTH*2+2,y+2,"%d",now-Prior);

}

else

{

putimage(x+1,y+1,black,COPY_PUT);

putimage(x+1+WIDTH,y+1,black,COPY_PUT);

putimage(x+1+WIDTH*2,y+1,black,COPY_PUT);

gprintf(x+2,y+2,"system idle process");

}

now = now-Next;

}

}

int DlgGetNum(char *buf,int l,int t,int r,int b,int gettime)

{

char ch;

int pos=0;

bar(l,t,r,b);

gprintf(l+10,t+5,"Add new Process");

if (gettime)

gprintf(l+10,t+20,"input the time:");

else

gprintf(l+10,t+20,"input the priority:");

while (1)

{

ch = getch();

if (ch == ENTER)/*如果输入了回车键*/

{

if(pos!=0)/*如果位置不在第一位(回车键不准第一个输入)*/

{

buf[pos]='\0';

break;

}

}

else if (ch='0' ch='9')

{

buf[pos++]=ch;

buf[pos]='\0';

}

else if (ch == ESC)

{

return FALSE;

}

else/*其他按键均按BackSpace处理*/

{

--pos;

buf[pos]='\0';

}

if (pos0)

{ pos=0; buf[pos]='\0';}

else if (pos4)/*最多输入4位数*/

{ pos=4; buf[pos]='\0';}

bar(l,t+35,r,t+47);

gprintf(l+50,t+35,buf);

}

return TRUE;

}

int NewProcDlg()

{

int l=200,t=150,r=380,b=200,pos=0,prior=0,time=0;

char buf[5],ch;

PCB *pcb;

void* bg = (void*)malloc(imagesize(l,t,r,b));

getimage(l,t,r,b,bg);

setfillstyle(1,2);

flushall();

/*******输入优先级**********/

if (!DlgGetNum(buf,l,t,r,b,FALSE))

goto exit;

prior = atoi(buf);

/*******输入时间**********/

pos=0;

buf[pos]='\0';

if (!DlgGetNum(buf,l,t,r,b,TRUE))

goto exit;

time = atoi(buf);

InsertProc(prior, time);

exit:

putimage(l,t,bg,COPY_PUT);

free(bg);

return TRUE;

}

int gprintf( int xloc, int yloc, char *fmt, ... )/*图形系统中的格式输出*/

{

va_list argptr; /* Argument list pointer */

char str[140]; /* Buffer to build sting into */

int cnt; /* Result of SPRINTF for return */

va_start( argptr, format ); /* Initialize va_ functions */

cnt = vsprintf( str, fmt, argptr ); /* prints string to buffer */

outtextxy( xloc, yloc, str ); /* Send string in graphics mode */

va_end( argptr ); /* Close va_ functions */

return( cnt ); /* Return the conversion count */

}

/****************************************************************/

/*main函数*/

int main()

{

clock_t start=0, end=0;

char kb;

InitBatchs(3);/*初始化为3道系统*/

InitGraph();

while (1)

{

start = end = clock();

while (!kbhit())

{

start = clock();

if ((start-end)/18.2 = 1)/*时间过了一秒*/

{

start = end = clock();

PassSeconds(1);

cleardevice();

DrawFrame();

DrawData();

}

}

kb = getch();

switch (kb)

{

case ESC:

closegraph();

return 0;

case 'w':

AddBatch();

UpdateBatchs();

cleardevice();

DrawFrame();

DrawData();

break;

case 's':

DeleteBatch();

UpdateBatchs();

cleardevice();

DrawFrame();

DrawData();

break;

case 'i':

NewProcDlg();

UpdateBatchs();

DrawFrame();

DrawData();

break;

}

}

return 0;

}

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