Java IO _ instance operations-notes for single-user information management programs

Java IO _ instance operations-notes for single-user information management programs

Instance requirements:

Expand the previous menu program. The requirement is that the complete information of a person can be added when the program is added. The information of a person includes the name and age. You can modify or delete this information after saving it. How can this code be completed?
Tip: save with Object serialization.

In this case, the program can use the following classes: inputdata, person, operate, and menu. You need to add a file operation class to save and read the file content, and modify the operate class to add specific operations for it.

File Operation class:

Import Java. io. file; import Java. io. fileinputstream; import Java. io. fileoutputstream; import Java. io. objectinputstream; import Java. io. objectoutputstream; public class fileoperate {private file = NULL; Public fileoperate (string pathname) {This. file = new file (pathname);} public Boolean save (Object OBJ) throws exception {objectoutputstream OOS = NULL; Boolean flag = false; // define the operation flag. Try {OOS = new o Bjectoutputstream (New fileoutputstream (this. file); OOS. writeobject (OBJ); flag = true;} catch (exception e) {Throw E; // an exception is thrown to the called for processing.} finally {If (OOS! = NULL) {OOS. close () ;}return flag;} public object load () throws exception {object OBJ = NULL; objectinputstream OIS = NULL; try {OIS = new objectinputstream (New fileinputstream (this. file); OBJ = Ois. readobject (); // read object} catch (exception e) {Throw E;} finally {If (OIS! = NULL) {Ois. Close (); // close} return OBJ ;}}

Operations are personnel information, so you must define the person class.

Import Java. io. serializable; public class person implements serializable {private string name; private int age; Public Person (string name, int age) {This. name = Name; this. age = age;} Public String tostring () {return "name:" + this. name + "; age:" + this. age;} public void setname (string name) {This. name = Name;} public void setage (INT age) {This. age = age;} Public String getname () {return this. name;} public int ageage () {return this. age ;}}

Modify operation class:

Public class operate {public static void add () {inputdata input = new inputdata (); fileoperate fo = new fileoperate ("d :\\ test. per "); string name = input. getstring ("Enter name:"); int age = input. getint ("Enter age:", "age must be a number! "); Person per = new person (name, age); // instantiate the person object try {fo. save (PER);} catch (exception e) {e. printstacktrace ();} system. out. println ("information added successfully! ");} Public static void Delete () {fileoperate fo = new fileoperate (" D: \ test. per "); try {fo. save (null); // Save the object} catch (exception e) {e. printstacktrace ();} system. out. println ("information deleted successfully! ");} Public static void Update () {inputdata input = new inputdata (); fileoperate fo = new fileoperate (" d :\\ test. per "); person per = NULL; try {per = (person) fo. load (); // read object} catch (exception e) {e. printstacktrace ();} string name = input. getstring ("Enter the name (original name:" + per. getname () + ")"); int age = input. getint ("Enter age (original age:" + per. getage () + ")", "age must be a number"); Per = new person (name, age); // instantiate the person object try {fo. sav E (PER);} catch (exception e) {e. printstacktrace ();} system. Out. println ("Information modified successfully! ");} Public static void find () {fileoperate fo = new fileoperate (" D: \ test. per "); person per = NULL; try {per = (person) fo. load ();} catch (exception e) {e. printstacktrace ();} system. out. println (PER );}}

Compile the inputdata class

Import Java. io. *; import Java. util. *; import Java. text. *; public class inputdata {private bufferedreader Buf = NULL; Public inputdata () {This. buf = new bufferedreader (New inputstreamreader (system. in);} Public String getstring (string info) {string temp = NULL; system. out. print (Info); // print the prompt message try {temp = This. buf. readline ();} catch (ioexception e) {e. printstacktrace ();} return temp;} public int Geti NT (string info, string ERR) {int temp = 0; string STR = NULL; Boolean flag = true; while (FLAG) {STR = This. getstring (Info); If (Str. matches ("^ \ D + $") {// determines whether a number is composed of temp = integer. parseint (STR); flag = false;} else {system. out. println (ERR) ;}} return temp;} public float getfloat (string info, string ERR) {float temp = 0; string STR = NULL; Boolean flag = true; while (FLAG) {STR = This. getstring (Info); If (Str. Matches ("^ \ D + .? \ D + $ ") {temp = float. parsefloat (STR); flag = false;} else {system. out. println (ERR) ;}} return temp;} public date getdate (string info, string ERR) {date temp = NULL; string STR = NULL; Boolean flag = true; while (FLAG) {STR = This. getstring (Info); If (Str. matches ("^ \ D {4}-\ D {2}-\ D {2} $ ")) {simpledateformat SDF = new simpledateformat ("yyyy-mm-dd"); try {temp = SDF. parse (STR);} catch (exception e) {} flag = false;} else {system. out. println (ERR) ;}} return temp ;}}

Test the inputdata class

Import Java. io. *; import Java. util. *; public class testinput {public static void main (string ARGs []) throws exception {inputdata input = new inputdata (); // float F = input. getfloat ("Please enter decimal places:", "the input is not a decimal point. Please enter it again! "); // System. out. println ("decimal:" + F); Date d = input. getdate ("Enter the date in the format of (yyyy-mm-dd):", "the input date format is incorrect. Please enter it again"); system. out. println ("date" + d );}};

Compile menu

Public Class Menu {public menu () {While (true) {This. show (); // unlimited call menu display} public void show () {system. out. println ("==== XXX system ===="); system. out. println ("[1], add data"); system. out. println ("[2], delete data"); system. out. println ("[3], modify data"); system. out. println ("[4], View data"); system. out. println ("[0], system logout \ n"); inputdata input = new inputdata (); int I = input. getint ("select:", "enter the correct option! "); Switch (I) {Case 1: {operate. add (); // call the add operation break;} Case 2: {operate. delete (); // call the delete operation break;} Case 3: {operate. update (); // call the update operation break;} case 4: {operate. find (); // call to view the break;} case 0: {system. exit (1); // exit break;} default: {system. out. println ("select the correct operation! ");}}}};

Client type

import java.io.* ;public class ExecDemo03{    public static void main(String args[]) throws Exception{        new Menu() ;    }};

Operation successful: