简单绑定包含 Java 中的 Key()方法，示例
原文:https://www . geesforgeks . org/simplebindings-contains key-method-in-Java-with-examples/
如果支持此简单绑定对象的映射包含指定键的映射，则使用简单绑定类的 containsKey() 方法返回 true。如果 SimpleBindings 对象包含该键，则该方法返回 true 否则返回 false。
语法:
public boolean containsKey(Object key)
参数:该方法只接受一个参数键，该键在该地图中的存在性有待检验。
返回值:如果该映射包含指定键的映射，则该方法返回真。
异常:该方法抛出以下异常:
- null 指针异常:唉呀关键点吾曰空值
- 类种姓例外:如果键不是线
- 非法引数异常:关键子串
演示 containsKey()方法工作原理的 Java 程序:
程序 1:
// Java program to demonstrate containsKey() method
import javax.script.SimpleBindings;
public class GFG {
public static void main(String[] args)
{
// create simpleBindings object
SimpleBindings bindings = new SimpleBindings();
// add some keys with values
bindings.put("key1", "value1");
bindings.put("key2", "value2");
bindings.put("key3", "value3");
// check key2 is exists in bindings or not
boolean isKey2Exist = bindings.containsKey("key2");
// print
System.out.println("Key2 exits:" + isKey2Exist);
}
}
输出:
Key2 exits:true
程序二:
// Java program to demonstrate containsKey() method
import javax.script.SimpleBindings;
public class GFG {
public static void main(String[] args)
{
// create simpleBindings object
SimpleBindings asiaTeamList
= new SimpleBindings();
// add team in asiaTeamList
asiaTeamList.put("team1", "India");
asiaTeamList.put("team2", "Sri Lanka");
asiaTeamList.put("team3", "Pakistan");
asiaTeamList.put("team4", "Bangladesh");
// check England exists in bindings or not
boolean isKey2Exist
= asiaTeamList.containsKey("England");
// print
System.out.println("England exits in Asia Team:"
+ isKey2Exist);
}
}
输出:
England exits in Asia Team:false
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