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java的輸入語句小結(jié)
Java中做輸入的方式:通過控制臺輸入數(shù)據(jù),需要使用Scanner對象來操作，那么java輸入語句到底有哪些呢?下面跟yjbys小編一起來看看吧!
1.使用Scanner
使用時需要引入包import java.util.Scanner;首先定義Scanner對象
Scanner sc = new Scanner(System.in);
如果要輸入整數(shù)，則 int n = sc.nextInt();
String類型的，則String temp = sc.next();
比如：
import java.util.Scanner;
public class Test {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int[] days = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
int month = -1;
while(true) {
try {
System.out.print("請輸入月份：");
month = scanner.nextInt();
if(month >= 1 && month <= 12) {
break;
}
System.out.println("** 請輸入正確的月份 **");
} catch (Exception e) {
System.out.println("** 格式錯誤!請輸入數(shù)字 **");
scanner.next();
}
}
System.out.println(month + " 月份有：" + days[month - 1] + " 天");
}
}
2.使用BufferedReader
用前需要引入 import java.io.Reader;
BufferedReader br = new BufferedReader( new InputStreamReader(System.in) );
String input = br.readLine();
比如：
==================================================================================================
import java.io.*;
public class importtext {
public static void main(String[] args) {
String st;
int num;
float fnum;
try{
System.out.print("輸入：");
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
st = br.readLine();
System.out.print("輸入一個數(shù)：");
num = Integer.parseInt(br.readLine());
System.out.print("輸入一個浮點數(shù)：");
fnum = Float.parseFloat(br.readLine());
System.out.print("輸出："+st+'n');
System.out.print("輸出："+num+'n');
System.out.print("輸出："+fnum+'n');
}catch(IOException e){}
}
}
==================================================================================================
package com.s2;
import java.io.*;
public class Input
{
public static void main(String[] args)throws IOException
{
while(true)
{
BufferedReader buf;
String str;
buf =new BufferedReader(new InputStreamReader(System.in));
System.out.println("Input a string:");
str=buf.readLine();
System.out.println("String="+str);
}
}
}
==================================================================================================
應(yīng)該注意的是:Java把從鍵盤輸入的數(shù)據(jù)一律看作是字符串，因此若要從鍵盤輸入并讓系統(tǒng)認(rèn)可是數(shù)值型數(shù)據(jù)，必須經(jīng)過轉(zhuǎn)換。
比如：
package com.s2;
import java.io.*;
public class Input
{
public static void main(String[] args)throws IOException
{
while(true)
{
int num;
BufferedReader buf;
String str;
buf =new BufferedReader(new InputStreamReader(System.in));
System.out.println("Input an integer:");
str=buf.readLine();
num=Integer.parseInt(str);
System.out.println("String="+str);
System.out.println("Integer="+str);
}
}
}
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