Java Java类设置 1

PrintStream 向另一个输出流添加了功能，即能够方便地打印各种数据值的表示形式。与其他输出流不同，PrintStream 从不抛出 IOException；相反，异常情况只是设置一个内部标志，可以通过 checkError 方法进行测试。可选地，可以创建一个 PrintStream 以便自动刷新。
PrintStream 打印的所有字符都使用平台的默认字符编码转换为字节。 PrintWriter 类应该用于需要写入字符而不是字节的情况。

类声明

public class PrintStream
  extends FilterOutputStream
    implements Appendable, Closeable

场地

protected OutputStream out:This is the output stream to be filtered.

构造函数和描述

PrintStream(File file)：使用指定的文件创建一个新的打印流，不自动刷新行。
PrintStream(File file, String csn) ：使用指定的文件和字符集创建一个新的打印流，不自动刷新行。
PrintStream(OutputStream out) ：创建一个新的打印流。
PrintStream(OutputStream out, boolean autoFlush) ：创建一个新的打印流。
PrintStream(OutputStream out, boolean autoFlush, String encoding) ：创建一个新的打印流。
PrintStream(String fileName) ：使用指定的文件名创建一个新的打印流，不自动刷新行。
PrintStream(String fileName, String csn) ：使用指定的文件名和字符集创建一个新的打印流，不自动刷新行。

方法：

PrintStream append(char c) ：将指定的字符附加到此输出流。

Syntax :public PrintStream append(char c)
Parameters:
c - The 16-bit character to append
Returns:
This output stream

PrintStream append(CharSequence csq, int start, int end)：将指定的字符序列附加到此输出流。

Syntax :public PrintStream append(CharSequence csq,
                 int start,
                 int end)
Parameters:
csq - The character sequence from which a subsequence will be appended. 
start - The index of the first character in the subsequence
end - The index of the character following the last character in the subsequence
Returns:
This output stream
Throws:
IndexOutOfBoundsException

PrintStream append(CharSequence csq) ：将指定字符序列的子序列附加到此输出流。

Syntax :public PrintStream append(CharSequence csq)
Parameters:
csq - The character sequence to append. 
Returns:
This output stream

boolean checkError()：刷新流并检查其错误状态。

Syntax :public boolean checkError()
Returns:
true if and only if this stream has encountered an IOException 
other than InterruptedIOException, or the setError method has been invoked

protected void clearError() ：清除此流的内部错误状态。
```
Syntax :protected void clearError()
```

void close() ：关闭流。

Syntax :public void close()
Overrides:
close in class FilterOutputStream

void flush()：刷新流。

Syntax :public void flush()
Overrides:
flush in class FilterOutputStream

PrintStream format(Locale l, String format, Object... args)：使用指定的格式字符串和参数将格式化字符串写入此输出流。

Syntax :public PrintStream format(Locale l,
                 String format,
                 Object... args)
Parameters:
l - The locale to apply during formatting. 
If l is null then no localization is applied.
format - A format string as described in Format string syntax
args - Arguments referenced by the format specifiers in the format string. 
The number of arguments is variable and may be zero.
Returns:
This output stream
Throws:
IllegalFormatException 
NullPointerException

PrintStream format(String format, Object... args)：使用指定的格式字符串和参数将格式化字符串写入此输出流。

Syntax :public PrintStream format(String format,
                 Object... args)
Parameters:
format - A format string as described in Format string syntax
args - Arguments referenced by the format specifiers in the format string. 
The number of arguments is variable and may be zero.
Returns:
This output stream
Throws:
IllegalFormatException 
NullPointerException

void print(boolean b)：打印一个布尔值。
```
Syntax :public void print(boolean b)
```
void print(char c)：打印一个字符。
```
Syntax :public void print(char c)
```
void print(char[] s)：打印一个字符数组。
```
Syntax :public void print(char[] s)
```
void print(double d) ：打印一个双精度浮点数。
```
Syntax :public void print(double b)
```
void print(float f)：打印一个浮点数。
```
Syntax :public void print(float f)
```
void print(int i)：打印一个整数。
```
Syntax :public void print(int i)
```
void print(long l)：打印一个长整数。
```
Syntax :public void print(long l)
```
void print(Object obj) :打印一个对象。
```
Syntax :public void print(Object obj)
```
void print(String s)：打印一个字符串。
```
Syntax :public void print(String s)
```

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.PrintStream;
import java.util.Locale;
//Java program to demonstrate PrintStream methods
class Printstream
{
    public static void main(String args[]) throws FileNotFoundException
    {
        FileOutputStream fout=new FileOutputStream("file.txt");
          
        //creating Printstream obj
        PrintStream out=new PrintStream(fout);
        String s="First";
  
        //writing to file.txt
        char c[]={'G','E','E','K'};
          
        //illustrating print(boolean b) method
        out.print(true);
          
        //illustrating print(int i) method
        out.print(1);
          
        //illustrating print(float f) method
        out.print(4.533f);
          
        //illustrating print(String s) method
        out.print("GeeksforGeeks");
        out.println();
          
        //illustrating print(Object Obj) method
        out.print(fout);
        out.println();
          
        //illustrating append(CharSequence csq) method
        out.append("Geek");
        out.println();
          
        //illustrating checkError() method
        out.println(out.checkError());
          
        //illustrating format() method
        out.format(Locale.UK, "Welcome to my %s program", s);
          
        //illustrating flush method
        out.flush();
          
        //illustrating close method
        out.close();
    }
}

注意：在线 IDE 上可能看不到输出，因为它无法读取文件。
输出：

true14.533GeeksforGeeks
java.io.FileOutputStream@1540e19dGeek
false
Welcome to my First program

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