Java常用的输入输出语句

雨点打透心脏的1/2处 2022-05-21 11:29 254阅读 0赞

对于经常上机刷题的来说，首先得解决输入输出方法，Java的输入输出流在Java学习过程的后面部分才会接触，但是我们可以掌握一些简单的，常用的输入输出方法

首先**输出**

大家最熟悉的莫过于输出方法，直接用System.out.println()或者System.out.print()了下面一个实例

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      <code><span style="font-family:NSimsun;">public</span></code> 
      <code><span style="font-family:NSimsun;">class</span></code> 
      <code><span style="font-family:NSimsun;">Main{ </span></code> 
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      <span style="font-family:NSimsun;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>public</code></span> 
      <code><span style="font-family:NSimsun;">static</span></code> 
      <code><span style="font-family:NSimsun;">void</span></code> 
      <code><span style="font-family:NSimsun;">main(String[] args){ </span></code> 
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      <span style="font-family:NSimsun;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>System.out.println(</code><code>"hello_1!"</code><code>);</code></span> 
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      <span style="font-family:NSimsun;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>System.out.print(</code><code>"hello_2!"</code><code>);</code></span> 
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      <span style="font-family:NSimsun;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>System.out.print(</code><code>"hello!_3"</code><code>);</code></span> 
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      <span style="font-family:NSimsun;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code></span> 
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      <code><span style="font-family:NSimsun;">}</span></code> 
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System.out.print()用于直接输出，System.out.println()也是直接输出，但在结束的地方会加一个换行

接下来看**输入**

如果你要进行输入，请一定加上两个包

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      <code><span style="font-family:NSimsun;">import</span></code> 
      <code><span style="font-family:NSimsun;">java.util.*;</span></code> 
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      <code><span style="font-family:NSimsun;">import</span></code> 
      <code><span style="font-family:NSimsun;">java.io.*;</span></code> 
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请看下面例子用于**输入单个字符**

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      <code><span style="font-family:NSimsun;">import</span></code> 
      <code><span style="font-family:NSimsun;">java.io.*;</span></code> 
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      <code><span style="font-family:NSimsun;">import</span></code> 
      <code><span style="font-family:NSimsun;">java.util.*;</span></code> 
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      <code><span style="font-family:NSimsun;">public</span></code> 
      <code><span style="font-family:NSimsun;">class</span></code> 
      <code><span style="font-family:NSimsun;">Main{ </span></code> 
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      <span style="font-family:NSimsun;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>public</code></span> 
      <code><span style="font-family:NSimsun;">static</span></code> 
      <code><span style="font-family:NSimsun;">void</span></code> 
      <span style="font-family:NSimsun;"><code>main(String[] args)</code><code>throws</code></span> 
      <code><span style="font-family:NSimsun;">IOException{ </span></code> 
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      <span style="font-family:NSimsun;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>char</code></span> 
      <span style="font-family:NSimsun;"><code>c=(</code><code>char</code><code>)System.in.read();</code></span> 
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      <span style="font-family:NSimsun;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>System.out.println(c);</code></span> 
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      <span style="font-family:NSimsun;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code></span> 
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      <code><span style="font-family:NSimsun;">}</span></code> 
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**输入整数或者字符（串）**

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      <code><span style="font-family:NSimsun;">import</span></code> 
      <code><span style="font-family:NSimsun;">java.io.*;</span></code> 
     </div> 
     <div> 
      <code><span style="font-family:NSimsun;">import</span></code> 
      <code><span style="font-family:NSimsun;">java.util.*;</span></code> 
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      <code><span style="font-family:NSimsun;">public</span></code> 
      <code><span style="font-family:NSimsun;">class</span></code> 
      <code><span style="font-family:NSimsun;">Main{ </span></code> 
     </div> 
     <div> 
      <span style="font-family:NSimsun;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>public</code></span> 
      <code><span style="font-family:NSimsun;">static</span></code> 
      <code><span style="font-family:NSimsun;">void</span></code> 
      <span style="font-family:NSimsun;"><code>main(String[] args)</code><code>throws</code></span> 
      <code><span style="font-family:NSimsun;">IOException{ </span></code> 
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      <span style="font-family:NSimsun;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>Scanner cin=</code><code>new</code></span> 
      <code><span style="font-family:NSimsun;">Scanner(System.in);</span></code> 
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      <code><span style="font-family:NSimsun;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span></code>&nbsp; 
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      <span style="font-family:NSimsun;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>int</code></span> 
      <span style="font-family:NSimsun;"><code>a=cin.nextInt();</code><code>//输入一个整数</code></span> 
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      <span style="font-family:NSimsun;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>System.out.println(a);</code></span> 
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      <code><span style="font-family:NSimsun;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span></code>&nbsp; 
     </div> 
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      <span style="font-family:NSimsun;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>double</code></span> 
      <span style="font-family:NSimsun;"><code>b=cin.nextDouble();</code><code>//输入一个双精度的浮点数</code></span> 
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      <span style="font-family:NSimsun;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>System.out.println(b);</code></span> 
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      <code><span style="font-family:NSimsun;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span></code>&nbsp; 
     </div> 
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      <span style="font-family:NSimsun;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>String str=cin.next();</code><code>//输入一个单词，遇到分号则输入终止</code></span> 
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      <span style="font-family:NSimsun;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>System.out.println(str);</code></span> 
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      <code><span style="font-family:NSimsun;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span></code>&nbsp; 
     </div> 
     <div> 
      <span style="font-family:NSimsun;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>String str2=cin.nextLine();</code><code>//输入一行，中间可有多个空格</code></span> 
     </div> 
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      <span style="font-family:NSimsun;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>System.out.println(str2);</code></span> 
     </div> 
     <div> 
      <span style="font-family:NSimsun;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code></span> 
     </div> 
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      <code><span style="font-family:NSimsun;">}</span></code> 
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**还可以用BufferedReader类输入**

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      <span style="color:#000000;"><code><span style="font-family:NSimsun;">import</span></code> <code><span style="font-family:NSimsun;">java.io.*;</span></code></span> 
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      <span style="color:#000000;"><code><span style="font-family:NSimsun;">import</span></code> <code><span style="font-family:NSimsun;">java.util.*;</span></code></span> 
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      <span style="color:#000000;"><code><span style="font-family:NSimsun;">public</span></code> <code><span style="font-family:NSimsun;">class</span></code> <code><span style="font-family:NSimsun;">Main{ </span></code></span> 
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      <span style="color:#000000;"><span style="font-family:NSimsun;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>public</code></span> <code><span style="font-family:NSimsun;">static</span></code> <code><span style="font-family:NSimsun;">void</span></code> <span style="font-family:NSimsun;"><code>main(String[] args)</code><code>throws</code></span> <code><span style="font-family:NSimsun;">IOException{ </span></code></span> 
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      <span style="color:#000000;"><span style="font-family:NSimsun;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>BufferedReader cin=</code><code>new</code></span> <span style="font-family:NSimsun;"><code>BufferedReader(</code><code>new</code></span> <code><span style="font-family:NSimsun;">InputStreamReader(System.in));</span></code></span> 
     </div> 
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      <span style="font-family:NSimsun;"><span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>String str=cin.readLine();</code><code>//输入一行</code></span></span> 
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      <span style="font-family:NSimsun;"><span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>System.out.println(str);</code></span></span> 
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      <span style="color:#000000;"><code><span style="font-family:NSimsun;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span></code>&nbsp;</span> 
     </div> 
     <div> 
      <span style="font-family:NSimsun;"><span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>String str2=cin.readLine();</code></span></span> 
     </div> 
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      <span style="color:#000000;"><span style="font-family:NSimsun;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>int</code></span> <span style="font-family:NSimsun;"><code>a=Integer.parseInt(str2);</code><code>//将str2转换为int,并复制给a</code></span></span> 
     </div> 
     <div> 
      <span style="font-family:NSimsun;"><span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>System.out.println(a);</code></span></span> 
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      <span style="color:#000000;"><code><span style="font-family:NSimsun;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span></code>&nbsp;</span> 
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      <span style="font-family:NSimsun;"><span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>String str3=cin.readLine();</code></span></span> 
     </div> 
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      <span style="color:#000000;"><span style="font-family:NSimsun;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>double</code></span> <span style="font-family:NSimsun;"><code>b=Double.parseDouble(str3);</code><code>//将str3转换为double,并复制给b</code></span></span> 
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      <span style="font-family:NSimsun;"><span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>System.out.println(b);</code></span></span> 
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      <span style="font-family:NSimsun;"><span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code></span></span> 
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      <code><span style="font-family:NSimsun;">}</span></code> 
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