Java中的 PrintStream setError() 方法及示例

Java中PrintStream类的setError()方法用于设置此 PrintStream 实例的错误状态。此方法用作指示流中发生错误的指示符。它受到保护，因此需要通过派生 PrintStream 类来使用它来实现。

句法：

protected void setError()

参数：此方法不接受任何参数。

返回值：此方法不返回任何内容。

下面的方法说明了 setError() 方法的工作原理：

方案一：

// Java program to demonstrate
// PrintStream setError() method
  
import java.io.*;
  
// extending the PrintStream Class
class GFG extends PrintStream {
  
    // Defining the protected constructor
    public GFG(OutputStream out)
    {
        super(System.out);
    }
  
    // Driver Code
    public static void main(String[] args)
    {
  
        // The string to be written in the Stream
        String str = "GeeksForGeeks";
  
        try {
  
            // Create a GFG instance
            GFG stream
                = new GFG(System.out);
  
            // Write the above string to this stream
            // This will put the string in the stream
            // till it is printed on the console
            stream.print(str);
  
            stream.flush();
  
            // Use the protected setError() method
            stream.setError();
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

输出：

GeeksForGeeks

方案二：

// Java program to demonstrate
// PrintStream setError() method
  
import java.io.*;
  
// extending the PrintStream Class
class GFG extends PrintStream {
  
    // Defining the protected constructor
    public GFG(OutputStream out)
    {
        super(System.out);
    }
  
    // Driver Code
    public static void main(String[] args)
    {
  
        try {
  
            // Create a GFG instance
            GFG stream
                = new GFG(System.out);
  
            // Write the char to this stream
            // This will put the char in the stream
            // till it is printed on the console
            stream.write(65);
  
            stream.flush();
  
            // Use the protected setError() method
            stream.setError();
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

输出：