如何在文件中按名称搜索？

Question

如何在包含名称和年龄的对象的文件中按名称查找？我想从文件中按名称搜索它。我完成了将对象写入文件并从文件中读取的操作。Demo object1 = new Demo(100,"saran");Demo object2 = new Demo(20 ,"nivas");ArrayList<Demo> list=new ArrayList<>();try {    FileOutputStream file=new FileOutputStream("C:\\Users\\SARANNIVAS\\Documents\\file\\obj");    ObjectOutputStream out=new ObjectOutputStream(file);    list.add(object1);    list.add(object2);    out.writeObject(list);    out.close();    file.close();    System.out.println("object has been serialized");} catch(IOException ex){     ex.printStackTrace();    System.out.println("exception is caught");}try {    FileInputStream file=new FileInputStream("C:\\Users\\SARANNIVAS\\Documents\\file\\obj");    ObjectInputStream in=new ObjectInputStream(file);    ArrayList<Demo> list1=new ArrayList<>();    list1=(ArrayList<Demo>)in.readObject();    for(Demo d:list1) {        System.out.println(d.a);        System.out.println(d.b);    }} catch(IOException ex) {     System.out.println("IOException is caught"); }

Answer 1

我假设您正在尝试搜索您从文件中读回的数组列表。它是否正确？您可以使用类似...的方式搜索列表

public class DemoDemo {

    public static void main(String[] args) {

        Demo object1 = new Demo(100,"saran");

        Demo object2 = new Demo(20 ,"nivas");

        List<Demo> list=new ArrayList<>();

        list.add(object1);

        list.add(object2);

        list

          .stream()

             .filter(d1 -> d1.name.equalsIgnoreCase("saran"))

                .forEach(d2 -> System.out.println(d2.name + " of age " + d2.age));

    }

}

class Demo {

    public final int age;

    public final String name;

    public Demo (int age, String name) {

        this.age = age;

        this.name = name;

    }

}