如何在运行时销毁和重新创建 Android 中的对象？
How to destroy and recreate objects in Android during runtime?
我正在开发一个 Android 应用程序，它必须模拟某种 Pokédex。
现在，我想做的只是在我的设备上打印所有 151 只神奇宝贝，这样我就可以上下滚动它们。
问题是，当我用 9 或 12 张图片尝试这个东西时没有问题，但是当我加载所有 151 张图片（所有 .png）时，Android 杀死了应用程序，因为它是耗尽太多系统资源。
我听说有 Java 方法可以（不知道如何）"destroy" 一个对象，当它离开显示时，然后重新创建它 returns 在屏幕上。无论如何，如果您对如何解决我的问题有不同的建议，欢迎提出意见！
这是我的 MainActivity：
package com.example.thefe.newsmartkedex;
import android.media.AudioManager;
import android.media.SoundPool;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.GridView;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
GridView gridview = (GridView) findViewById(R.id.gridview);
gridview.setAdapter(new ImageAdapter(this));
gridview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View v,
int position, long id) {
Toast.makeText(MainActivity.this, "" + position,
Toast.LENGTH_SHORT).show();
}
});
};
}
这是我的 ImageAdapter class 我用于 Gridview：
package com.example.thefe.newsmartkedex;
import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
public class ImageAdapter extends BaseAdapter {
private Context mContext;
public ImageAdapter(Context c) {
mContext = c;
}
public int getCount() {
return mThumbIds.length;
}
public Object getItem(int position) {
return null;
}
public long getItemId(int position) {
return 0;
}
// create a new ImageView for each item referenced by the Adapter
public View getView(int position, View convertView, ViewGroup parent) {
ImageView imageView;
if (convertView == null) {
// if it's not recycled, initialize some attributes
imageView = new ImageView(mContext);
imageView.setLayoutParams(new GridView.LayoutParams(200, 200));
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
imageView.setPadding(8, 8, 8, 8);
} else {
imageView = (ImageView) convertView;
}
imageView.setImageResource(mThumbIds[position]);
return imageView;
}
// references to our images
private Integer[] mThumbIds = {
R.drawable.pkmn1, R.drawable.pkmn2,
R.drawable.pkmn3, R.drawable.pkmn4,
R.drawable.pkmn5, R.drawable.pkmn6,
R.drawable.pkmn7, R.drawable.pkmn8,
R.drawable.pkmn9, R.drawable.pkmn10,
R.drawable.pkmn11, R.drawable.pkmn12,
R.drawable.pkmn13, R.drawable.pkmn14,
R.drawable.pkmn15, R.drawable.pkmn16,
R.drawable.pkmn17, R.drawable.pkmn18,
R.drawable.pkmn19, R.drawable.pkmn20,
R.drawable.pkmn21, R.drawable.pkmn22,
R.drawable.pkmn23, R.drawable.pkmn24,
R.drawable.pkmn25, R.drawable.pkmn26,
R.drawable.pkmn27, R.drawable.pkmn28,
R.drawable.pkmn29, R.drawable.pkmn30,
R.drawable.pkmn31, R.drawable.pkmn32,
R.drawable.pkmn33, R.drawable.pkmn34,
R.drawable.pkmn35, R.drawable.pkmn36,
R.drawable.pkmn37, R.drawable.pkmn38,
R.drawable.pkmn39, R.drawable.pkmn40,
R.drawable.pkmn41, R.drawable.pkmn42,
R.drawable.pkmn43, R.drawable.pkmn44,
R.drawable.pkmn45, R.drawable.pkmn46,
R.drawable.pkmn47, R.drawable.pkmn48,
R.drawable.pkmn49, R.drawable.pkmn50,
R.drawable.pkmn51, R.drawable.pkmn52,
R.drawable.pkmn53, R.drawable.pkmn54,
R.drawable.pkmn55, R.drawable.pkmn56,
R.drawable.pkmn57, R.drawable.pkmn58,
R.drawable.pkmn59, R.drawable.pkmn60,
R.drawable.pkmn61, R.drawable.pkmn62,
R.drawable.pkmn63, R.drawable.pkmn64,
R.drawable.pkmn65, R.drawable.pkmn66,
R.drawable.pkmn67, R.drawable.pkmn68,
R.drawable.pkmn69, R.drawable.pkmn70,
R.drawable.pkmn71, R.drawable.pkmn72,
R.drawable.pkmn73, R.drawable.pkmn74,
R.drawable.pkmn75, R.drawable.pkmn76,
R.drawable.pkmn77, R.drawable.pkmn78,
R.drawable.pkmn79, R.drawable.pkmn80,
R.drawable.pkmn81, R.drawable.pkmn82,
R.drawable.pkmn83, R.drawable.pkmn84,
R.drawable.pkmn85, R.drawable.pkmn86,
R.drawable.pkmn87, R.drawable.pkmn88,
R.drawable.pkmn89, R.drawable.pkmn90,
R.drawable.pkmn91, R.drawable.pkmn92,
R.drawable.pkmn93, R.drawable.pkmn94,
R.drawable.pkmn95, R.drawable.pkmn96,
R.drawable.pkmn97, R.drawable.pkmn98,
R.drawable.pkmn99, R.drawable.pkmn100,
R.drawable.pkmn101, R.drawable.pkmn102,
R.drawable.pkmn103, R.drawable.pkmn104,
R.drawable.pkmn105, R.drawable.pkmn106,
R.drawable.pkmn107, R.drawable.pkmn108,
R.drawable.pkmn109, R.drawable.pkmn110,
R.drawable.pkmn111, R.drawable.pkmn112,
R.drawable.pkmn113, R.drawable.pkmn114,
R.drawable.pkmn115, R.drawable.pkmn116,
R.drawable.pkmn117, R.drawable.pkmn118,
R.drawable.pkmn119, R.drawable.pkmn120,
R.drawable.pkmn121, R.drawable.pkmn122,
R.drawable.pkmn123, R.drawable.pkmn124,
R.drawable.pkmn125, R.drawable.pkmn126,
R.drawable.pkmn127, R.drawable.pkmn128,
R.drawable.pkmn129, R.drawable.pkmn130,
R.drawable.pkmn131, R.drawable.pkmn132,
R.drawable.pkmn133, R.drawable.pkmn134,
R.drawable.pkmn135, R.drawable.pkmn136,
R.drawable.pkmn137, R.drawable.pkmn138,
R.drawable.pkmn139, R.drawable.pkmn140,
R.drawable.pkmn141, R.drawable.pkmn142,
R.drawable.pkmn143, R.drawable.pkmn144,
R.drawable.pkmn145, R.drawable.pkmn146,
R.drawable.pkmn147, R.drawable.pkmn148,
R.drawable.pkmn149, R.drawable.pkmn150,
R.drawable.pkmn151
};
}
最后，这是 XML 文件
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.thefe.newsmartkedex.MainActivity">
<GridView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/gridview"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:columnWidth="90dp"
android:numColumns="auto_fit"
android:verticalSpacing="10dp"
android:horizontalSpacing="10dp"
android:stretchMode="columnWidth"
android:gravity="center"
/>
</RelativeLayout>
感谢帮助！
显示适合您的屏幕的有限图像，并在滚动 Gridview 时加载其他图像。
这样系统就不必一次做很多工作了。您的应用程序也变得更快。
你可以参考这个link:
i want grid view with loading by scroll i have image fetch from sever but i want only 10 images view other can load when scrolling grid view
首先，我没有发现你的代码有任何违规行为，所以让我们关注一下图片。
The problem is that when I try this thing with such as 9 or 12 images there are no problems, but when I load all the 151 images (all .png), Android kills the app because it's draining too much system resources.
'load all the 151 images' 是什么意思？同时在同一屏幕上？或者你只是让他们中的相当一部分（比如 9、12、16 等）在视图中看到而其他人在屏幕之外？
I've heard that there are Java methods that can (don't know how) "destroy" an object when it goes out of the display and then recreate it when it returns in the screen. Anyway if you have different suggestions on how to resolve my problem, every idea is welcome!
您不能简单地自行销毁一个对象，当您的对象无效或未使用时，Jvm 会为您处理。对于这个问题，您在 'getView' 中实现的对象的重新创建似乎没有什么害处。
我的问题是：你一屏显示了多少张图片？它们有多大？
如果你能在这里提供你的演示，那将是最好的工作。
我正在开发一个 Android 应用程序，它必须模拟某种 Pokédex。
现在，我想做的只是在我的设备上打印所有 151 只神奇宝贝，这样我就可以上下滚动它们。
问题是，当我用 9 或 12 张图片尝试这个东西时没有问题，但是当我加载所有 151 张图片（所有 .png）时，Android 杀死了应用程序，因为它是耗尽太多系统资源。
我听说有 Java 方法可以（不知道如何）"destroy" 一个对象，当它离开显示时，然后重新创建它 returns 在屏幕上。无论如何，如果您对如何解决我的问题有不同的建议，欢迎提出意见！
这是我的 MainActivity：
package com.example.thefe.newsmartkedex;
import android.media.AudioManager;
import android.media.SoundPool;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.GridView;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
GridView gridview = (GridView) findViewById(R.id.gridview);
gridview.setAdapter(new ImageAdapter(this));
gridview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View v,
int position, long id) {
Toast.makeText(MainActivity.this, "" + position,
Toast.LENGTH_SHORT).show();
}
});
};
}
这是我的 ImageAdapter class 我用于 Gridview：
package com.example.thefe.newsmartkedex;
import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
public class ImageAdapter extends BaseAdapter {
private Context mContext;
public ImageAdapter(Context c) {
mContext = c;
}
public int getCount() {
return mThumbIds.length;
}
public Object getItem(int position) {
return null;
}
public long getItemId(int position) {
return 0;
}
// create a new ImageView for each item referenced by the Adapter
public View getView(int position, View convertView, ViewGroup parent) {
ImageView imageView;
if (convertView == null) {
// if it's not recycled, initialize some attributes
imageView = new ImageView(mContext);
imageView.setLayoutParams(new GridView.LayoutParams(200, 200));
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
imageView.setPadding(8, 8, 8, 8);
} else {
imageView = (ImageView) convertView;
}
imageView.setImageResource(mThumbIds[position]);
return imageView;
}
// references to our images
private Integer[] mThumbIds = {
R.drawable.pkmn1, R.drawable.pkmn2,
R.drawable.pkmn3, R.drawable.pkmn4,
R.drawable.pkmn5, R.drawable.pkmn6,
R.drawable.pkmn7, R.drawable.pkmn8,
R.drawable.pkmn9, R.drawable.pkmn10,
R.drawable.pkmn11, R.drawable.pkmn12,
R.drawable.pkmn13, R.drawable.pkmn14,
R.drawable.pkmn15, R.drawable.pkmn16,
R.drawable.pkmn17, R.drawable.pkmn18,
R.drawable.pkmn19, R.drawable.pkmn20,
R.drawable.pkmn21, R.drawable.pkmn22,
R.drawable.pkmn23, R.drawable.pkmn24,
R.drawable.pkmn25, R.drawable.pkmn26,
R.drawable.pkmn27, R.drawable.pkmn28,
R.drawable.pkmn29, R.drawable.pkmn30,
R.drawable.pkmn31, R.drawable.pkmn32,
R.drawable.pkmn33, R.drawable.pkmn34,
R.drawable.pkmn35, R.drawable.pkmn36,
R.drawable.pkmn37, R.drawable.pkmn38,
R.drawable.pkmn39, R.drawable.pkmn40,
R.drawable.pkmn41, R.drawable.pkmn42,
R.drawable.pkmn43, R.drawable.pkmn44,
R.drawable.pkmn45, R.drawable.pkmn46,
R.drawable.pkmn47, R.drawable.pkmn48,
R.drawable.pkmn49, R.drawable.pkmn50,
R.drawable.pkmn51, R.drawable.pkmn52,
R.drawable.pkmn53, R.drawable.pkmn54,
R.drawable.pkmn55, R.drawable.pkmn56,
R.drawable.pkmn57, R.drawable.pkmn58,
R.drawable.pkmn59, R.drawable.pkmn60,
R.drawable.pkmn61, R.drawable.pkmn62,
R.drawable.pkmn63, R.drawable.pkmn64,
R.drawable.pkmn65, R.drawable.pkmn66,
R.drawable.pkmn67, R.drawable.pkmn68,
R.drawable.pkmn69, R.drawable.pkmn70,
R.drawable.pkmn71, R.drawable.pkmn72,
R.drawable.pkmn73, R.drawable.pkmn74,
R.drawable.pkmn75, R.drawable.pkmn76,
R.drawable.pkmn77, R.drawable.pkmn78,
R.drawable.pkmn79, R.drawable.pkmn80,
R.drawable.pkmn81, R.drawable.pkmn82,
R.drawable.pkmn83, R.drawable.pkmn84,
R.drawable.pkmn85, R.drawable.pkmn86,
R.drawable.pkmn87, R.drawable.pkmn88,
R.drawable.pkmn89, R.drawable.pkmn90,
R.drawable.pkmn91, R.drawable.pkmn92,
R.drawable.pkmn93, R.drawable.pkmn94,
R.drawable.pkmn95, R.drawable.pkmn96,
R.drawable.pkmn97, R.drawable.pkmn98,
R.drawable.pkmn99, R.drawable.pkmn100,
R.drawable.pkmn101, R.drawable.pkmn102,
R.drawable.pkmn103, R.drawable.pkmn104,
R.drawable.pkmn105, R.drawable.pkmn106,
R.drawable.pkmn107, R.drawable.pkmn108,
R.drawable.pkmn109, R.drawable.pkmn110,
R.drawable.pkmn111, R.drawable.pkmn112,
R.drawable.pkmn113, R.drawable.pkmn114,
R.drawable.pkmn115, R.drawable.pkmn116,
R.drawable.pkmn117, R.drawable.pkmn118,
R.drawable.pkmn119, R.drawable.pkmn120,
R.drawable.pkmn121, R.drawable.pkmn122,
R.drawable.pkmn123, R.drawable.pkmn124,
R.drawable.pkmn125, R.drawable.pkmn126,
R.drawable.pkmn127, R.drawable.pkmn128,
R.drawable.pkmn129, R.drawable.pkmn130,
R.drawable.pkmn131, R.drawable.pkmn132,
R.drawable.pkmn133, R.drawable.pkmn134,
R.drawable.pkmn135, R.drawable.pkmn136,
R.drawable.pkmn137, R.drawable.pkmn138,
R.drawable.pkmn139, R.drawable.pkmn140,
R.drawable.pkmn141, R.drawable.pkmn142,
R.drawable.pkmn143, R.drawable.pkmn144,
R.drawable.pkmn145, R.drawable.pkmn146,
R.drawable.pkmn147, R.drawable.pkmn148,
R.drawable.pkmn149, R.drawable.pkmn150,
R.drawable.pkmn151
};
}
最后，这是 XML 文件
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.thefe.newsmartkedex.MainActivity">
<GridView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/gridview"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:columnWidth="90dp"
android:numColumns="auto_fit"
android:verticalSpacing="10dp"
android:horizontalSpacing="10dp"
android:stretchMode="columnWidth"
android:gravity="center"
/>
</RelativeLayout>
感谢帮助！
显示适合您的屏幕的有限图像，并在滚动 Gridview 时加载其他图像。
这样系统就不必一次做很多工作了。您的应用程序也变得更快。
你可以参考这个link:
i want grid view with loading by scroll i have image fetch from sever but i want only 10 images view other can load when scrolling grid view
首先，我没有发现你的代码有任何违规行为，所以让我们关注一下图片。
The problem is that when I try this thing with such as 9 or 12 images there are no problems, but when I load all the 151 images (all .png), Android kills the app because it's draining too much system resources.
'load all the 151 images' 是什么意思？同时在同一屏幕上？或者你只是让他们中的相当一部分（比如 9、12、16 等）在视图中看到而其他人在屏幕之外？
I've heard that there are Java methods that can (don't know how) "destroy" an object when it goes out of the display and then recreate it when it returns in the screen. Anyway if you have different suggestions on how to resolve my problem, every idea is welcome!
您不能简单地自行销毁一个对象，当您的对象无效或未使用时，Jvm 会为您处理。对于这个问题，您在 'getView' 中实现的对象的重新创建似乎没有什么害处。
我的问题是：你一屏显示了多少张图片？它们有多大？
如果你能在这里提供你的演示，那将是最好的工作。