AN IMPROTANT COLLECTION OF JAVA IO RELATED PROGRAMS

Transcription

1 JAVALEARNINGS.COM AN IMPROTANT COLLECTION OF JAVA IO RELATED PROGRAMS Visit for more pdf downloads and interview related questions JAVALEARNINGS.COM

2 /* Write a program to write n number of student records in a data file and search the data file on the basis of roll no.,name,marks */ import java.util.*; import java.io.*; class Student implements Serializable public String name; public int roll; public float marks; Student() //System.out.println("Student Record Created"); public void input() throws IOException BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); System.out.print(" Name of the Student: "); name = br.readline(); System.out.print(" Roll No. of the Student: "); roll = Integer.parseInt(br.readLine()); System.out.print(" Marks of the Student: "); marks = Float.parseFloat(br.readLine()); public void display() System.out.println("\tName: "+name); System.out.println("\tRoll No.: "+roll); System.out.println("\tMarks: "+marks); class ObjectWrite static File path = new File("objwrite.dat"); public static void main(string args[]) throws IOException

3 int z; Student temp = new Student(); Scanner sc = new Scanner(System.in); BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); System.out.println("\n\t Serialization/DeSerialization \n"); System.out.println("\n 1.Write \n 2.Read \n 3.Search \n 4.Exit"); System.out.print(" Your Choice: "); z = sc.nextint(); switch(z) case 1: ObjectWrite.write(); break; case 2: ObjectWrite.read(); break; case 3: System.out.println("\n\t\t Searching from file: "+path); int choice; System.out.println("\n\t 1.Using Name \n\t 2.Using Marks \n\t 3.Using RollNo."); System.out.print(" Your Choice: "); choice = sc.nextint(); switch(choice) case 1: System.out.println(" Enter Name to be Searched: "); String tname = br.readline(); searchname(tname); break;

4 case 2: System.out.println(" Enter Marks to be Searched: "); float marks = Float.parseFloat(br.readLine()); searchmarks(marks); break; case 3: System.out.println(" Enter RollNo. to be Searched: "); int roll = Integer.parseInt(br.readLine()); searchroll(roll); break; default: System.out.println("\n Poor Choice "); ObjectWrite.main(new String[] "Poor","Choice","Entered"); Encountered"); case 4: System.exit(0); default: System.out.println("\n Wrong Input ObjectWrite.main(new String[] "Wrong","Input","Encountered"); public static void write() throws IOException System.out.println(" Writing Objects to the File: "+path+"\n"); int i;

5 Scanner sc = new Scanner(System.in); System.out.println("\n Enter the Number of Students: "); int n = sc.nextint(); Student s[] = new Student[n+1]; //writing to the file FileOutputStream out = new FileOutputStream(path); ObjectOutputStream oos = new ObjectOutputStream(out); System.out.println("\n Enter the Details: "); for(i=0;i<n;i++) s[i] = new Student(); System.out.print("\n"); s[i].input(); oos.writeobject(s[i]); oos.flush(); s[i] = new Student(); s[i].name = "EOF"; s[i].roll = -1; s[i].marks = -1; oos.close(); out.close(); System.out.println("\n Writing Complete \n"); public static void read() throws IOException //reading from the file FileInputStream in = new FileInputStream(path); ObjectInputStream ois = new ObjectInputStream(in); System.out.println("\n Reading Objects from the File: "+path+"\n"); try Student temp=(student)ois.readobject(); while(true) if(temp.roll==-1) break; else

6 Complete"); temp.display(); System.out.print("\n"); temp=(student)ois.readobject(); ois.close(); catch(throwable e) System.out.println("End of File Reached\n Reading public static void searchname(string tname ) throws IOException //reading from the file FileInputStream in = new FileInputStream(path); ObjectInputStream ois = new ObjectInputStream(in); try Student temp=(student)ois.readobject(); while(true) if(temp.roll==-1) break; else if(temp.name.startswith(tname) temp.name.endswith(tname)) System.out.println("\t Record Found \t"); temp.display(); System.out.print("\n"); temp=(student)ois.readobject(); ois.close();

7 catch(throwable e) System.out.println("End of File Reached\n Searching Complete"); public static void searchmarks(float marks ) throws IOException //reading from the file FileInputStream in = new FileInputStream(path); ObjectInputStream ois = new ObjectInputStream(in); try Student temp=(student)ois.readobject(); while(true) if(temp.roll==-1) break; else if(temp.marks==marks) System.out.println("\t Record Found \t"); temp.display(); System.out.print("\n"); temp=(student)ois.readobject(); ois.close(); catch(throwable e) System.out.println("End of File Reached\n Searching Complete"); public static void searchroll(int roll ) throws IOException //reading from the file FileInputStream in = new FileInputStream(path);

8 ObjectInputStream ois = new ObjectInputStream(in); try Student temp=(student)ois.readobject(); while(true) if(temp.roll==-1) break; else if(temp.roll==roll) System.out.println("\t Record Found \t"); temp.display(); System.out.print("\n"); temp=(student)ois.readobject(); ois.close(); catch(throwable e) System.out.println("End of File Reached\n Searching Complete");

9 /* Write a program to copy the contents of one file to another */ import java.util.*; import java.io.*; class FileCopy public static void main(string args[]) throws IOException File f1 = new File(args[0]); File f2 = new File(args[1]); FileInputStream in = null; FileOutputStream out = null; System.out.println(" Writing the Contents to: "+f1+"\n"); BufferedInputStream br = new BufferedInputStream(System.in); BufferedReader b = new BufferedReader(new InputStreamReader(System.in)); char c; int i; String temp; out = new FileOutputStream(f1); //writing to file f1 System.out.println("Enter Strings(@ to Exit Writing): \n"); i = br.read(); c = (char)i; while(c!='@') out.write(i); i = br.read(); c = (char)i; out.close(); //copying to file f2 System.out.println(" Copying the Contents of "+f1+" to "+f2+" \n"); in = new FileInputStream(f1); out = new FileOutputStream(f2); i = in.read(); while(i!=-1)

10 c = (char)i; out.write(i); i = in.read(); out.close(); "+f2); System.out.println("\n Write 'view' to view the contents of file: String v = b.readline(); if(v.equals("view") v.equals("view")) System.out.println("Done"); else System.exit(0); //displaying the contents of f2 in = new FileInputStream(f2); i = in.read(); while(i!=-1) c = (char)i; System.out.print(c); i = in.read();

11 /* Write a program to count the number of words in a text file */ import java.util.*; import java.io.*; class WordCount public static void main(string args[]) throws IOException String name; String text; int count=1; char c; int i; BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); System.out.println(" Enter the Name for the File: "); name = br.readline(); File f = new File(name); System.out.println("\n We got a file: "+f); System.out.println("\n Does it extisted before: "+f.exists()); System.out.println("\n Is it a Directory: "+f.isdirectory()); FileWriter out = new FileWriter(f); System.out.println("\n Enter the text to the File(Write 'qq' to end writing): \n"); text = br.readline(); while(!(text.equals("qq"))) char temp[] = new char[text.length()]; text.getchars(0,text.length(),temp,0); int n = temp.length; for(i=0;i<n;i++) out.write(temp[i]); text = br.readline(); out.close(); System.out.println("\n Writng Done on File: "+f);

12 System.out.println("\n Counting the Number of Words in the File: "+f); FileReader in = new FileReader(f); i = in.read(); while(i!=-1) c = (char)i; if(c==32 c=='\n') count++; System.out.print(c); i = in.read(); System.out.println("\n Number of Words in the File "+f+" are: "+(count));

13 /* Write a program to create encrypt and decrypt the contents of a text file */ import java.util.*; import java.io.*; class EncryptData static int er=0,pass=0; public static void main(string args[]) throws IOException int er =0,pass =0; int c; char a; File path = new File(args[0]); //creating a FileObject FileReader in = null; //For Reading from File FileWriter out = null; //For Writing to File Scanner sc = new Scanner(System.in); String test; System.out.println("\n We got a File: "+path); //File Details System.out.println("\n Does it Exists: "+path.exists()); //File Details System.out.println("\n Is Directory: "+path.isdirectory()); //File Details encryption out = new FileWriter(path); //writng to File System.out.println("\n Encryption Process: \n\n"); EncryptData.encrypt(out); //calling function for out.close(); er = EncryptData.er; pass = EncryptData.pass; System.out.println("er = "+er+" pass"+pass);

14 "); decryption in = new FileReader(path); System.out.println("\n Displaying Encrypted Contents of the File: c = in.read(); while(c!=-1) a = (char)c; System.out.print(a); c = in.read(); in = new FileReader(path); System.out.println("\n\n Decryption Process: \n\n"); System.out.println("Write 'view' to view the Decrypted File Data"); test = sc.nextline(); if(test.equals("view") test.equals("view")) EncryptData.decrypt(in,pass); //calling function for public static void encrypt(filewriter out) throws IOException String l; int n,c,er=0,pass=0; char a; BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); System.out.println("\n Enter the Data to be written on the File:(qq to stop wirting) \n\n"); l = br.readline(); while(!(l.equals("qq"))) char[] arr = new char[l.length()]; n = arr.length; //System.out.println("Char Arr length: l.getchars(0,l.length(),arr,0); for(int i=0;i<n;i++,er++) "+n);

15 c = arr[i]-er; a = (char)c; //System.out.print(" err : "+er); out.write(a); if(er==20) er=-1; pass++; l = br.readline(); out.close(); EncryptData.er = er-2; EncryptData.pass = pass; public static void decrypt(filereader in,int pass) throws IOException //function to decrypt data from file int c,n,er=0; char a; c = in.read(); do if(er>20) er=0; if(c==10) er = 0; System.out.println("\n"); n = c+er; a = (char)n; System.out.print(a); er++; c = in.read(); while(c!=-1);

16 /* Write a program to search the files starting with a perticular string in directory */ import java.util.*; import java.io.*; class FileSearch public static void main(string args[]) throws IOException int i; Scanner sc = new Scanner(System.in); System.out.println(" Enter the name of the Directory(e.g: C:\\Himanshu)"); String aa = sc.nextline(); File path = new File(aa); String[] s =path.list(); System.out.println("Enter part of Name of File To Be Searched:(e.g: First Name or Extension)"); String l = sc.nextline(); int loc=-1; int a; if(path.isdirectory()) System.out.println("Is directory: "+path.isdirectory()); for(i=0,a=0;i<s.length;i++,a++) //System.out.println("S.NO.: "+a+1+" : "+s[i]); if(s[i].startswith(l) s[i].endswith(l)) loc = i; System.out.println(s[i]+" --> Found at Loc:\t"+loc+"\n"); if(loc==-1) System.out.println("Not found");

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18 /* Write a program to pass the contents of a student from a html file to a java program for finding the result */ import java.util.*; import java.applet.*; import java.awt.*; // <applet code="applettest.class" height=500 width=500 /> public class AppletTest extends Applet String s; int m1,m2,m3,m4; public void init() //setforeground(color.black); //setbackground(color.red); public void start() s = getparameter("name"); m1 = Integer.parseInt(getParameter("sub1")); m2 = Integer.parseInt(getParameter("sub2")); m3 = Integer.parseInt(getParameter("sub3")); m4 = Integer.parseInt(getParameter("sub4")); public void paint(graphics g) g.drawstring(" Applet Testing ",100,100); g.drawstring("name: "+s,100,140); g.drawstring("subject 1 Marks: "+m1,110,180); g.drawstring("subject 2 Marks: "+m2,110,220); g.drawstring("subject 3 Marks: "+m3,110,260); g.drawstring("subject 4 Marks: "+m4,110,300); g.drawstring("total Marks: "+(m1+m2+m3+m4),110,340); g.drawstring("total Marks: "+((m1+m2+m3+m4)/4),110,380);