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法学研究在Java中，有多少种方法可以读取键盘输入的数据？
**java.io**包提供了各种类，用于从各种来源读取和写入数据到各种目标。
您可以使用各种类（例如，Scanner、BufferedReader、InputStreamReader、Console等）从用户（键盘）读取数据。
使用Scanner类
从Java 1.5开始引入Scanner类。此类接受File、InputStream、Path和String对象，使用正则表达式逐个标记读取所有基本数据类型和字符串（来自给定来源）。默认情况下，空格被视为分隔符（用于将数据分成标记）。
要从键盘读取数据，您需要使用标准输入作为来源（System.in）。对于每种数据类型，都提供了nextXXX()方法，例如nextInt()、nextShort()、nextFloat()、nextLong()、nextBigDecimal()、nextBigInteger()、nextLong()、nextShort()、nextDouble()、nextByte()、nextFloat()、next()。
示例
下面的Java程序使用Scanner类从用户读取数据。
import java.util.Scanner;
class Student{
String name;
int age;
float percent;
boolean isLocal;
char grade;
Student(String name, int age, float percent, boolean isLocal, char grade){
this.name = name;
this.age = age;
this.percent = percent;
this.isLocal = isLocal;
this.grade = grade;
}
public void displayDetails(){
System.out.println("Details..............");
System.out.println("Name: "+this.name);
System.out.println("Age: "+this.age);
System.out.println("Percent: "+this.percent);
if(this.isLocal) {
System.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[]) {
Scanner sc =new Scanner(System.in);
System.out.println("Enter your name: ");
String name = sc.next();
System.out.println("Enter your age: ");
int age = sc.nextInt();
System.out.println("Enter your percent: ");
float percent = sc.nextFloat();
System.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 Student(name, age, percent, isLocal, grade);
std.displayDetails();
}
}输出
Enter your name: Krishna Enter your age: 25 Enter your percent: 86 Are you local (enter true or false): true Enter your grade(enter A, or, B or, C or, D): A Details.............. Name: Krishna Age: 25 Percent: 86.0 Nationality: Indian Grade: A
使用BufferedReader
Java的BufferedReader类用于从指定来源（字符输入流）读取字符流。此类的构造函数接受InputStream对象作为参数，您可以传递一个**InputStreamReader**。
示例
下面的Java程序使用**BufferedReader**类从用户读取数据。
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
class Student{
String name;
int age;
float percent;
boolean isLocal;
char grade;
Student(String name, int age, float percent, boolean isLocal, char grade){
this.name = name;
this.age = age;
this.percent = percent;
this.isLocal = isLocal;
this.grade = grade;
}
public void displayDetails(){
System.out.println("Details..............");
System.out.println("Name: "+this.name);
System.out.println("Age: "+this.age);
System.out.println("Percent: "+this.percent);
if(this.isLocal) {
System.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 {
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 percent: ");
float percent = Float.parseFloat(reader.readLine());
System.out.println("Are you 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(name, age, percent, isLocal, grade);
std.displayDetails();
}
}输出
Enter your name: Krishna Enter your age: 25 Enter your percent: 86 Are you local (enter true or false): true Enter your grade(enter A, or, B or, C or, D): A Details.............. Name: Krishna Age: 25 Percent: 86.0 Nationality: Indian Grade: A
使用Console类
此类用于与控制台（键盘/屏幕）设备写入/读取数据。它提供了一个**readLine()**方法，该方法从键盘读取一行。您可以使用**console()**方法获取Console类的对象。
**注意** - 如果您尝试在非交互式环境（如IDE）中执行此程序，它将无法工作。
示例
下面的Java程序使用**Console**类从用户读取数据。
import java.io.BufferedReader;
import java.io.Console;
import java.io.IOException;
import java.io.InputStreamReader;
class Student{
String name;
int age;
float percent;
boolean isLocal;
char grade;
Student(String name, int age, float percent, boolean isLocal, char grade){
this.name = name;
this.age = age;
this.percent = percent;
this.isLocal = isLocal;
this.grade = grade;
}
public void displayDetails(){
System.out.println("Details..............");
System.out.println("Name: "+this.name);
System.out.println("Age: "+this.age);
System.out.println("Percent: "+this.percent);
if(this.isLocal) {
System.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 == null) {
System.out.println("Console is not supported");
System.exit(1);
}
System.out.println("Enter your name: ");
String name = console.readLine();
System.out.println("Enter your age: ");
int age = Integer.parseInt(console.readLine());
System.out.println("Enter your percent: ");
float percent = Float.parseFloat(console.readLine());
System.out.println("Are you local (enter true or false): ");
boolean isLocal = Boolean.parseBoolean(console.readLine());
System.out.println("Enter your grade(enter A, or, B or, C or, D): ");
char grade = console.readLine().toCharArray()[0];
Student std = new Student(name, age, percent, isLocal, grade);
std.displayDetails();
}
}输出
Enter your name: Krishna Enter your age: 26 Enter your percent: 86 Are you local (enter true or false): true Enter your grade(enter A, or, B or, C or, D): A Details.............. Name: Krishna Age: 26 Percent: 86.0 Nationality: Indian Grade: A
更新于：2019年8月1日
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