Java 中的属性列表(PrintWriter)方法,示例

原文:https://www . geesforgeks . org/properties-listprintwister-method-in-Java-with-examples/

属性类列表(PrintWriter) 方法用于将该属性列表打印到指定的输出流中,作为参数传递。此方法可用于调试目的,因为它有助于查看流中的属性元素。0

语法:

public void list(PrintWriter out)

参数:该方法接受一个参数 PrintWriter out ,该参数是要在其上打印属性元素的输出流。

返回:这个方法只是打印元素,不返回任何东西。

异常:如果该属性列表中的任意键不是字符串,则该方法抛出 ClassCastException

下面的程序展示了 int list(PrintWriter)方法的实现。

程序 1:

// Java code to show the implementation of
// list(PrintWriter) method

import java.util.*;
import java.io.*;

public class GfG {

    // Main method
    public static void main(String[] args)
    {

        // Create a properties and add some values
        Properties properties = new Properties();
        properties.put("Pen", "10");
        properties.put("Book", "500");
        properties.put("Clothes", "400");
        properties.put("Mobile", "5000");

        // Print Properties details
        System.out.println("Properties: "
                           + properties.toString());

        PrintWriter writer = new PrintWriter(System.out);

        // print the list with a PrintWriter object
        properties.list(writer);

        // flush the stream and display
        System.out.println("listing out the Properties: ");
        writer.flush();
    }
}

输出:

Properties: {Book=500, Mobile=5000, Pen=10, Clothes=400}
listing out the Properties: 
-- listing properties --
Book=500
Pen=10
Mobile=5000
Clothes=400

程序二:

// Java program to demonstrate
// list(PrintWriter) method.

import java.util.*;
import java.io.*;

public class GFG {

    // Main method
    public static void main(String[] args)
    {

        // Create a properties and add some values
        Properties properties = new Properties();

        // Inserting elements into the properties
        properties.put("Geeks", "10");
        properties.put("4", "15");
        properties.put("Geeks", "20");
        properties.put("Welcomes", "25");
        properties.put("You", "30");

        // Print Properties details
        System.out.println("Properties: "
                           + properties.toString());

        PrintWriter writer = new PrintWriter(System.out);

        // print the list with a PrintWriter object
        properties.list(writer);

        // flush the stream and display
        System.out.println("listing out the Properties: ");
        writer.flush();
    }
}

输出:

Properties: {You=30, Welcomes=25, 4=15, Geeks=20}
listing out the Properties: 
-- listing properties --
You=30
4=15
Welcomes=25
Geeks=20

参考文献:https://docs . Oracle . com/javase/9/docs/API/Java/util/properties . html # list-Java . io . printwriter-