Java 实例 - 只读集合
Java 教程
· 2019-02-11 17:29:43
以下实例演示了如何使用 Collection 类的 Collections.unmodifiableList() 方法来设置集合为只读：
Main.java 文件
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
public class Main {
public static void main(String[] argv)
throws Exception {
List stuff = Arrays.asList(new String[] { "a", "b" });
List list = new ArrayList(stuff);
list = Collections.unmodifiableList(list);
try {
list.set(0, "new value");
}
catch (UnsupportedOperationException e) {
}
Set set = new HashSet(stuff);
set = Collections.unmodifiableSet(set);
Map map = new HashMap();
map = Collections.unmodifiableMap(map);
System.out.println("集合现在是只读");
}
}
以上代码运行输出结果为：
集合现在是只读
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