Java Read in a Character String From Keyboard

How many means tin can we read data from the keyboard in Java?

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The java.io package provides various classes to read write information from various sources and destinations.

Yous tin read information from user (keyboard) using various classes such as, Scanner, BufferedReader, InputStreamReader, Panel etc.

Using Scanner course

From Java 1.5 Scanner form was introduced. This class accepts a File, InputStream, Path and, String objects, reads all the primitive data types and Strings (from the given source) token by token using regular expressions. By default, whitespace is considered as the delimiter (to break the data into tokens).

To read data from keyboard you lot need to utilize standard input equally source (System.in). For each datatype a nextXXX() is provided namely, nextInt(), nextShort(), nextFloat(), nextLong(), nextBigDecimal(), nextBigInteger(), nextLong(), nextShort(), nextDouble(), nextByte(), nextFloat(), side by side().

Case

Following Coffee program reads data from user using the Scanner class.

import java.util.Scanner; class Pupil{    String name;    int age;    float percent;    boolean isLocal;    char grade;    Student(String name, int historic period, float per centum, boolean isLocal, char grade){       this.proper name = name;       this.historic period = age;       this.percentage = per centum;       this.isLocal = isLocal;       this.course = grade;    }    public void displayDetails(){       System.out.println("Details..............");       Organization.out.println("Name: "+this.proper name);       System.out.println("Age: "+this.historic period);       System.out.println("Percent: "+this.percent);       if(this.isLocal) {          Organization.out.println("Nationality: Indian");       }else {          System.out.println("Nationality: Foreigner");       }       Organisation.out.println("Grade: "+this.form);    } } public class ReadData {    public static void master(String args[]) {       Scanner sc =new Scanner(System.in);       System.out.println("Enter your name: ");       String name = sc.next();       System.out.println("Enter your age: ");       int historic period = sc.nextInt();       System.out.println("Enter your percentage: ");       bladder percentage = sc.nextFloat();       Organization.out.println("Are you local (enter true or false): ");       boolean isLocal = sc.nextBoolean();       System.out.println("Enter your grade(enter A, or, B or, C or, D): ");       char grade = sc.next().toCharArray()[0];       Student std = new Educatee(proper noun, age, percent, isLocal, grade);       std.displayDetails();    } }

Output

Enter your name: Krishna Enter your age: 25 Enter your percent: 86 Are you local (enter true or false): true Enter your form(enter A, or, B or, C or, D): A Details.............. Name: Krishna Age: 25 Percent: 86.0 Nationality: Indian Grade: A

Using BufferedReader

The BufferedReader class of Java is used to read stream of characters from the specified source (character-input stream). The constructor of this class accepts an InputStream object every bit a parameter, you lot can to laissez passer an InputStreamReader.

Example

Following Java program reads data from user using the BufferedReaderclass.

import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; course Student{    Cord proper noun;    int age;    float percent;    boolean isLocal;    char grade;    Student(Cord name, int age, float percent, boolean isLocal, char grade){       this.proper name = proper name;       this.age = age;       this.percent = per centum;       this.isLocal = isLocal;       this.grade = grade;    }    public void displayDetails(){       System.out.println("Details..............");       System.out.println("Name: "+this.name);       Organization.out.println("Age: "+this.age);       System.out.println("Percent: "+this.percent);       if(this.isLocal) {          System.out.println("Nationality: Indian");       }else {          System.out.println("Nationality: Greenhorn");       }       System.out.println("Grade: "+this.grade);    } } public class ReadData {    public static void chief(Cord args[]) throws IOException {       BufferedReader reader =new BufferedReader(new InputStreamReader(System.in));       System.out.println("Enter your name: ");       String name = reader.readLine();       System.out.println("Enter your age: ");       int age = Integer.parseInt(reader.readLine());       System.out.println("Enter your percentage: ");       float percentage = Float.parseFloat(reader.readLine());       System.out.println("Are yous local (enter true or false): ");       boolean isLocal = Boolean.parseBoolean(reader.readLine());       System.out.println("Enter your grade(enter A, or, B or, C or, D): ");       char grade = (char) reader.read();       Student std = new Student(proper name, age, percent, isLocal, grade);       std.displayDetails();    } }

Output

Enter your name: Krishna Enter your age: 25 Enter your pct: 86 Are you local (enter true or simulated): truthful Enter your grade(enter A, or, B or, C or, D): A Details.............. Name: Krishna Historic period: 25 Percent: 86.0 Nationality: Indian Grade: A

Using Console class

This form is used to write/read information from the console (keyboard/screen) devices. It provides a readLine()method which reads a line from the key-board. You lot can go an object of the Console class using the console() method.

Note − If y'all try to execute this program in a non-interactive environment like IDE it doesn't piece of work.

Example

Following Coffee program reads data from user using the Panelgrade.

import coffee.io.BufferedReader; import java.io.Console; import java.io.IOException; import java.io.InputStreamReader; class Student{    String proper noun;    int historic period;    float per centum;    boolean isLocal;    char grade;    Student(Cord name, int age, float percent, boolean isLocal, char grade){       this.proper noun = name;       this.age = historic period;       this.percent = percentage;       this.isLocal = isLocal;       this.course = form;    }    public void displayDetails(){       System.out.println("Details..............");       System.out.println("Name: "+this.proper name);       Arrangement.out.println("Age: "+this.age);       Organisation.out.println("Percent: "+this.percent);       if(this.isLocal) {          Arrangement.out.println("Nationality: Indian");       }else {          System.out.println("Nationality: Foreigner");       }       System.out.println("Grade: "+this.grade);    } } public class ReadData {    public static void main(String args[]) throws IOException {       Console console = System.console();       if (console == cipher) {          System.out.println("Panel is not supported");          System.exit(1);       }       Arrangement.out.println("Enter your name: ");       String name = panel.readLine();       System.out.println("Enter your historic period: ");       int age = Integer.parseInt(console.readLine());       Organisation.out.println("Enter your percent: ");       float per centum = Float.parseFloat(console.readLine());       System.out.println("Are yous local (enter true or false): ");       boolean isLocal = Boolean.parseBoolean(panel.readLine());       System.out.println("Enter your grade(enter A, or, B or, C or, D): ");       char form = console.readLine().toCharArray()[0];       Student std = new Student(name, age, pct, isLocal, grade);       std.displayDetails();    } }

Output

Enter your name: Krishna Enter your age: 26 Enter your per centum: 86 Are you lot local (enter true or false): true Enter your grade(enter A, or, B or, C or, D): A Details.............. Proper noun: Krishna Age: 26 Percent: 86.0 Nationality: Indian Grade: A

Published on 01-Aug-2019 xiv:27:57

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