java程序-编译原理实验

最新推荐文章于 2022-07-29 14:02:46 发布

yuanshanchao

最新推荐文章于 2022-07-29 14:02:46 发布

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分类专栏： java 文章标签： java string 数据结构 import class 编程

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java课的程序实验不难写，但其它和编程有关的实验却很难写，数据结构实验如此，数值分析实验如此，现在学编译原理也如此，当初数据结构的二叉树程序我想都懒得去想，感觉毫无头绪。这次的编译原理上个星期布置的实验，明天要交报告了，今天正好星期天，用了大半天的时间终于被我凑出了结果。结构很乱，尤其是很多重复的代码，没有用到重构，自己看着都不好意思。算了反正写出来了。

import java.io. * ;

import java.util.StringTokenizer;

public class test {

public static int enter_count = 0;

public static int space_count = 0;

public static void main(String args[]){

int i = 0,j = 0,k = 0,n = 0,m = 0;

int count = 0,count1 = 0;

String s1[]=new String[20];

String s2[]=new String[20];

String s3[]=new String[20];

String s4[]=new String[20];

String s5[]=new String[20];

String s6[]=new String[20];

String s7[]=new String[20];

String s8[]=new String[20];

String s9[]=new String[20];

String s10[]=new String[20];

String s11[]=new String[20];

String s12[]=new String[20];

try{

//计算行数

FileInputStream fis = new FileInputStream("myfile.txt");

DataInputStream dis = new DataInputStream(fis);

while(dis.readLine()!=null){

enter_count++;

}

//将每一行符值给一个字符串

fis = new FileInputStream("myfile.txt");//由于上面的dis.readLine()将文件读完了，所以要从新初始化一遍

dis = new DataInputStream(fis);

String s[] = new String[enter_count];

i = 0;

while(dis.available()!=0){

s[i] = dis.readLine();

s1[i]=s[i];

i++;

}

dis.close();

//将每个字符串以空格分割

for(i=0;i<enter_count;i++){

StringTokenizer space = new StringTokenizer(s[i]," ");

space_count = space.countTokens();

while(space.hasMoreTokens()){

s2[n]=space.nextToken();

n++;

j++;

}

j=0;

}

//将每个字符串以"+"号分开

n=0;

for(i=0;i<6;i++){

StringTokenizer space = new StringTokenizer(s2[i],"+",true);

space_count = space.countTokens();

while(space.hasMoreTokens()){

s3[n]=space.nextToken();

n++;

j++;

count++;

}

j=0;

}

count1=count;

count=0;

//s4

n=0;

for(i=0;i<count1;i++){

StringTokenizer space = new StringTokenizer(s3[i],"-",true);

space_count = space.countTokens();

while(space.hasMoreTokens()){

s4[n]=space.nextToken();

n++;

j++;

count++;

}

j=0;

}

count1=count;

count = 0;

//s5

n=0;

for(i=0;i<count1;i++){

StringTokenizer space = new StringTokenizer(s4[i],"*",true);

space_count = space.countTokens();

while(space.hasMoreTokens()){

s5[n]=space.nextToken();

n++;

j++;

count++;

}

j=0;

}

count1=count;

count = 0;

//s6

n=0;

for(i=0;i<count1;i++){

StringTokenizer space = new StringTokenizer(s5[i],"/",true);

space_count = space.countTokens();

while(space.hasMoreTokens()){

s6[n]=space.nextToken();

n++;

j++;

count++;

}

j=0;

}

count1=count;

count = 0;

//s7

n=0;

for(i=0;i<count1;i++){

StringTokenizer space = new StringTokenizer(s6[i],"<",true);

space_count = space.countTokens();

while(space.hasMoreTokens()){

s7[n]=space.nextToken();

n++;

j++;

count++;

}

j=0;

}

count1=count;

count = 0;

//s8

n=0;

for(i=0;i<count1;i++){

StringTokenizer space = new StringTokenizer(s7[i],">",true);

space_count = space.countTokens();

while(space.hasMoreTokens()){

s8[n]=space.nextToken();

n++;

j++;

count++;

}

j=0;

}

count1=count;

count = 0;

//s9

n=0;

for(i=0;i<count1;i++){

StringTokenizer space = new StringTokenizer(s8[i],"=",true);

space_count = space.countTokens();

while(space.hasMoreTokens()){

s9[n]=space.nextToken();

n++;

j++;

count++;

}

j=0;

}

count1=count;

count = 0;

//s10

n=0;

for(i=0;i<count1;i++){

StringTokenizer space = new StringTokenizer(s9[i],"(",true);

space_count = space.countTokens();

while(space.hasMoreTokens()){

s10[n]=space.nextToken();

n++;

j++;

count++;

}

j=0;

}

count1=count;

count = 0;

//s11

n=0;

for(i=0;i<count1;i++){

StringTokenizer space = new StringTokenizer(s10[i],")",true);

space_count = space.countTokens();

while(space.hasMoreTokens()){

s11[n]=space.nextToken();

n++;

j++;

count++;

}

j=0;

}

count1=count;

count = 0;

//s12

n=0;

for(i=0;i<count1;i++){

StringTokenizer space = new StringTokenizer(s11[i],";",true);

space_count = space.countTokens();

while(space.hasMoreTokens()){

s12[n]=space.nextToken();

n++;

j++;

count++;

}

j=0;

}

count1=count;

count = 0;

//去处空格

String s_final[]=new String[count1];

for(i=0;i<count1;i++){

s_final[i]=s12[i].trim();

}

//判断前缀

boolean word=false;

for(i=0;i<count1;i++){

word=false;

//如果是关键字

String keyword[]={"if","then","else","while","do"};

for(j=0;j<5;j++){

if(s_final[i].compareTo(keyword[j])==0){

System.out.println("<"+s_final[i]+","+"->");

word=true;

}

//如果是运算符或界符

String operators[]={"+","-","*","/","<",">","=","(",")",";"};

for(j=0;j<10;j++){

if(s_final[i].compareTo(operators[j])==0){

System.out.println("<"+s_final[i]+","+"->");

word=true;

}

if(word){

continue;

}

//如果是十进制

if((s_final[i].compareTo("0")==0)||s_final[i].startsWith("1")||s_final[i].startsWith("2")||s_final[i].startsWith("3")||s_final[i].startsWith("4")||s_final[i].startsWith("5")||s_final[i].startsWith("6")||s_final[i].startsWith("7")||s_final[i].startsWith("8")||s_final[i].startsWith("9")){

System.out.println("<1,"+s_final[i]+">");

}

//如果是八进制