java - 无法使用服务中的新值增加 ArrayList

Question

我试图在服务中填充一个名为 items 的 ArrayList，但是我从我的 Activity 中调用服务的所有内容只有第一个元素被填充到数组中。我不确定执行此操作的最佳方法是什么。我听说过使用绑定(bind)服务方法，但从我读到的内容来看，并不建议这样做。

如何在服务被销毁()之前将字符串存储在持久数组列表中

提前致谢

问题代码

    public void print_result(String orig) {
        Log.d(TAG, "HELLO WORLD:" + orig);
        int i = 0;
        items = new ArrayList<String>();
        if (items != null) {
            if (items.contains(orig)) {
                Log.d(TAG, "Element already exists exiting");
            } else {

                items.add(orig);

                Log.d(TAG, "Adding Element" + items);

            }

        } else {
            Log.d(TAG, "IS NULL");
        }
    }  

格雷厄姆

Activity

 package com.example;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;

public class ServicesDemo extends Activity implements OnClickListener {
    private static final String TAG = "ServicesDemo";
    Button buttonStart, buttonStop, buttonAdd;
    EditText Input;
    String x = "";// test pass to my service

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        buttonStart = (Button) findViewById(R.id.buttonStart);
        buttonStop = (Button) findViewById(R.id.buttonStop);
        buttonAdd = (Button) findViewById(R.id.buttonAdd);
        Input = (EditText) findViewById(R.id.INPUT);
        buttonStart.setOnClickListener(this);
        buttonStop.setOnClickListener(this);

    }

    public void onClick(View src) {
        switch (src.getId()) {
        case R.id.buttonStart:
            Log.d(TAG, "onClick: starting srvice");
            Intent dataIntent = new Intent(ServicesDemo.this, MyService.class);
            x = Input.getText().toString();
            dataIntent.putExtra("originator", x);
            startService(dataIntent);

            break;

        case R.id.buttonStop:

            Log.d(TAG, "onClick: stopping srvice");
            // implicit starting
            stopService(new Intent(this, MyService.class));
            break;

        case R.id.buttonAdd:

            Log.d(TAG, "ADDING VALUES");
            break;
        }

    }

    public static String getTag() {
        return TAG;
    }
}

服务

package com.example;

import java.util.ArrayList;

import android.app.Service;
import android.content.Intent;
import android.os.Bundle;
import android.os.IBinder;
import android.util.Log;
import android.widget.Toast;

public class MyService extends Service {

    ArrayList<String> items = null;

    public String ORIG = "";
    private static final String TAG = "MyService";
    public Bundle data = new Bundle();

    @Override
    public IBinder onBind(Intent intent) {

        return null;

    }

    public static String getTag() {
        return TAG;
    }

    @Override
    public void onCreate() {
        Toast.makeText(this, "My Service Created", Toast.LENGTH_LONG).show();

    }

    @Override
    public void onDestroy() {
        Toast.makeText(this, "My Service Stopped", Toast.LENGTH_LONG).show();
        Log.d(TAG, "onDestroy");

    }

    @Override
    public void onStart(Intent intent, int startid) {
        Log.d(TAG, "onStart");
        data = intent.getExtras();
        ORIG = data.getString("originator");
        Log.d(TAG, "onCreate");
        Thread initBkgdThread = new Thread(new Runnable() {
            public void run() {
                print_result(ORIG);
            }
        });
        initBkgdThread.start();
    }

    public void print_result(String orig) {
        Log.d(TAG, "HELLO WORLD:" + orig);
        int i = 0;
        items = new ArrayList<String>();
        if (items != null) {
            if (items.contains(orig)) {
                Log.d(TAG, "Element already exists exiting");
            } else {

                items.add(orig);

                Log.d(TAG, "Adding Element" + items);

            }

        } else {
            Log.d(TAG, "IS NULL");
        }
    }

}

Answer 1

每次调用时，您都在该方法中创建了一个新的 ArrayList 实例。您在任何时刻都将只有一个元素。

替换

ArrayList<String> items = null;

与

ArrayList<String> items = new ArrayList<String>();

并从 print_result 中删除实例化。