Cách dùng peekFirst() trong LinkedBlockingDeque Android

peekFirst() - Xem phần tử đầu không xóa

peekFirst() trả về phần tử ở đầu deque (head) hoặc null nếu rỗng. An toàn, không ném exception. Tương đương peek().

Code xử lý click

actionEvent.setOnClickListener(v -> {
    String first = linkedBlockingDeque.peekFirst();
    actionEvent.setText("peekFirst(): " + first); // "sai"
});

MainActivity.java

package com.example.myapplication;

import android.os.Build;
import android.os.Bundle;
import android.view.View;
import androidx.annotation.RequiresApi;
import androidx.appcompat.app.AppCompatActivity;
import android.widget.TextView;
import java.util.concurrent.LinkedBlockingDeque;

public class MainActivity extends AppCompatActivity {

    private LinkedBlockingDeque<String> linkedBlockingDeque;

    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        linkedBlockingDeque = new LinkedBlockingDeque<>();
        final TextView actionEvent = findViewById(R.id.actionEvent);

        linkedBlockingDeque.add("sai");
        linkedBlockingDeque.add("ram");
        linkedBlockingDeque.add("krishna");
        linkedBlockingDeque.add("prasad");
        linkedBlockingDeque.add("ram");

        actionEvent.setText("Deque: " + linkedBlockingDeque);

        actionEvent.setOnClickListener(v -> {
            actionEvent.setText("peekFirst(): " + linkedBlockingDeque.peekFirst());
        });
    }
}

So sánh