java - 查看 android 监视器图时，.release() 不会减少我的内存

Question

我已将 .release() 方法添加到我的脚本中并运行了 android 模拟器，在运行时我查看了我的 android 显示器并开始点击 TextView 播放声音。

但是当声音结束时没有释放内存，我做错了什么？

package com.example.android.miwok;

import android.media.MediaPlayer;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;

import java.util.ArrayList;

public class NumbersActivity extends AppCompatActivity {

private MediaPlayer mMediaPlayer;

private MediaPlayer.OnCompletionListener mCompletionListerner = new MediaPlayer.OnCompletionListener() {
    @Override
    public void onCompletion(MediaPlayer mediaPlayer) {
        releaseMediaPlayer();
    }
};

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.word_list);

    final ArrayList<Word> words = new ArrayList<>();    // <-- Creates list

    words.add(new Word("one", "lutti", R.raw.number_one, R.drawable.number_one));
    words.add(new Word("two", "otiiko", R.raw.number_two, R.drawable.number_two));
    words.add(new Word("three", "tolookosu", R.raw.number_three, R.drawable.number_three));
    words.add(new Word("four", "oyyisa", R.raw.number_four, R.drawable.number_four));
    words.add(new Word("five", "massokka", R.raw.number_five, R.drawable.number_five));
    words.add(new Word("six", "temmokka", R.raw.number_six, R.drawable.number_six));
    words.add(new Word("seven", "kenekaku", R.raw.number_seven, R.drawable.number_seven));
    words.add(new Word("eight", "kawinta", R.raw.number_eight, R.drawable.number_eight));
    words.add(new Word("nine", "wo'e", R.raw.number_nine, R.drawable.number_nine));
    words.add(new Word("ten", "na'aacha", R.raw.number_ten, R.drawable.number_ten));

    WordAdapter adapter = new WordAdapter(this, words, R.color.category_numbers);


    ListView listView = (ListView) findViewById(R.id.list);     // <-- id the Listview
    listView.setAdapter(adapter);

    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> adapterView, View view, int position, long l) {
            releaseMediaPlayer();
            Word word = words.get(position);
            mMediaPlayer = MediaPlayer.create(NumbersActivity.this, word.getAudioResourceId());
            mMediaPlayer.start();
            mMediaPlayer.setOnCompletionListener(mCompletionListerner);
        }
    });
}

private void releaseMediaPlayer() {
    if (mMediaPlayer != null) {
        mMediaPlayer.release();
        mMediaPlayer = null;
    }
}
}

Answer 1

Android(更普遍的是 Java)使用 Garbage Collector系统。

此收集器不会立即“收集”空闲内存，您无法准确决定它何时通过!因此，当您 .release() 一个对象或其他任何东西时，您将不得不等到 GC 决定是时候恢复了。

释放引用的唯一效果是告诉 GC 这个对象可以被垃圾回收...仅此而已 ;)

所以，回答你的问题:你没有做错任何事，你只需要等待并希望 GC。