属性包含 Java 中的键(值)方法，示例
原文:https://www . geesforgeks . org/properties-contains key value-method-in-Java-with-examples/
包含键(值)属性类 的方法用于检查该属性对象是否包含该键对其中任何键的映射。它将该值作为参数进行比较，并返回一个布尔值作为结果。
语法:
public Object containsKey(Object value)
参数:该方法接受一个参数值，该值是该属性中要搜索的关键字。
返回:该方法返回一个布尔值，说明该属性对象中是否存在该键的结果。
下面的程序说明了 containsKey(值)方法:
程序 1:
// Java program to demonstrate
// containsKey(value) method.
import java.util.*;
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("Current Properties: "
+ properties.toString());
// Check if Pen is present or not
// using containsKey()
System.out.println("Is Pen present: "
+ properties.containsKey("Pen"));
}
}
输出:
Current Properties: {Book=500, Mobile=5000, Pen=10, Clothes=400}
Is Pen present: true
程序二:
// Java program to demonstrate
// containsKey(value) method.
import java.util.*;
public class GFG {
// Main method
public static void main(String[] args)
{
// Create a properties and add some values
Properties properties = new Properties();
properties.put(1, "100RS");
properties.put(2, "500RS");
properties.put(3, "1000RS");
// print Properties details
System.out.println("Current Properties: "
+ properties.toString());
// Check if 5 is present or not
// using containsKey()
System.out.println("Is 5 present: "
+ properties.containsKey(5));
}
}
输出:
Current Properties: {3=1000RS, 2=500RS, 1=100RS}
Is 5 present: false
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