可能的android内存泄漏

Question

我有这个 android 项目，无法确定它为什么会占用内存？请注意，仅填充 RAM 不会进行任何处理。我已阅读 Android RAM issues 和 how to solve，但不知道该怎么做。我对android和java都是新手。

刚刚注意到（在 Android Monitor - RAM 中）我的应用仅使用 4MB 内存。 如果有人尝试运行（请执行 - MainActivity 是启动器，而 MyCanvas 只是用作视图的类），我可以使用高达 100 的速度变量（甚至更多），在 10 毫秒或更频繁地进行线程回调 -它没有问题。但是一旦我触摸并移动垃圾收集器就会暂停一切。

MyCanvas.java（用作视图）

package com.abc.mygraphics;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.View;

import java.util.Random;
import android.os.Handler;

public class MyCanvas extends View {

public static Paint paint;
//public static int n = 5000;
public static int N = 100, particleSize = 3;
public static int height, width;
public static float[][] pos = new float[N][2];
public static float[][] pos0 = new float[N][2];
//public static float distX, distY, dist;
Handler handler = new Handler();
public static int speed = 1;
public static int gravityX, gravityY;
public static Random random = new Random();
public static int[] colorList = new int[10];
public static int sphereSize = 100, M = 10;
public static float[] distance = new float[N];
public static int[][] gravity = new int[N][2];
public static boolean[] direction = new boolean[N];
public static int[] moved = new int[N];

public MyCanvas(Context context) {
    super(context);

    width = MainActivity.sharedPreferences.getInt("screenX", 200);
    height = MainActivity.sharedPreferences.getInt("screenY", 200);
    colorList = new int[]{Color.RED, 0xffff4000, 0xffffff00, 0xff40ff00, 0xff00ff00, 0xff00ff80, 0xff0080ff, 0xff0000ff, 0xffbf00ff, 0xffff0040};

    paint = new Paint();
    paint.setColor(Color.GRAY);
    int i;
    for (i = 0; i < N; i++) {
        pos[i][0] = random.nextInt(width);
        pos[i][1] = random.nextInt(height);
        pos0[i][0] = pos[i][0];
        pos0[i][1] = pos[i][1];
        moved[i] = 0;
        direction[i] = true;
    }

    final Runnable r = new Runnable() {
        public void run() {
            invalidate();
            handler.postDelayed(this, 100);
        }
    };
    handler.postDelayed(r, 100);
}

public static void changeGravity(){
    gravityX = MainActivity.sharedPreferences.getInt("x",200);
    gravityY =   MainActivity.sharedPreferences.getInt("y",200);
    // gravityY -= 68;
    for(int i=0;i<N;i++){
        calcDist(i);
    }
}

@Override
public void onDraw(Canvas canvas){
    int i;
    int x;  //remove at some poitnt
    canvas.drawColor(Color.BLACK);
    //canvas.drawCircle(gravityX,gravityY, 50, paint);

    for(i=0;i<N;i++) {
        setPosition(i);
        x =  random.nextInt(10);
        paint.setColor(colorList[x]);
        canvas.drawCircle(pos[i][0], pos[i][1], particleSize, paint);
    }
}

public static void setPosition(int i){
    // this is wrong
    if(moved[i] >= (int)distance[i]/speed){
        direction[i] = !direction[i];
        setGravity(i);
    }
    else{
        pos[i][0] = pos0[i][0] + speed*moved[i]*(gravity[i][0]- pos0[i][0])/distance[i];
        pos[i][1] = pos0[i][1] + speed*moved[i]*(gravity[i][1]- pos0[i][1])/distance[i];
        moved[i]++;
    }
}

public static void calcDist(int i){
    setGravity(i);
    distance[i] = (float) Math.sqrt( Math.pow((gravity[i][0]-pos[i][0]),2) +  Math.pow((gravity[i][1]-pos[i][1]),2) );
}

public static void setGravity(int i){

    // do not forget to set pos0 in both cases
    if(direction[i]){
        gravity[i][0] = gravityX;
        gravity[i][1] = gravityY;
    }

    else{
        // make this biased on radius of sphere
        gravity[i][0] =  random.nextInt(width);
        gravity[i][1]  = random.nextInt(height);
    }
    pos0[i][0] = pos[i][0];
    pos0[i][1]  = pos[i][1];
    moved[i]=0;
}



}

主Activity.java

package com.abc.mygraphics;

 import android.content.SharedPreferences;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.view.MotionEvent;
import android.view.Window;
import android.view.WindowManager; 
import android.widget.EditText;
import android.widget.TextView;

import com.abc.mygraphics.MyCanvas;

import org.w3c.dom.Text;

public class MainActivity extends AppCompatActivity {

//DrawingView dr = new DrawingView(this);

public  static SharedPreferences sharedPreferences;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);


    DisplayMetrics displaymetrics = new DisplayMetrics();
    getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
    int height = displaymetrics.heightPixels;
    int width = displaymetrics.widthPixels;


    sharedPreferences = getSharedPreferences( getPackageName() + "_preferences", MODE_PRIVATE);

    SharedPreferences.Editor editor = sharedPreferences.edit();
    editor.putInt("screenX",width);
    editor.putInt("screenY", height);
    editor.putInt("x", 200);
    editor.putInt("y", 200);
    editor.commit();
    setContentView(new MyCanvas(this));
}

@Override
public boolean onTouchEvent(MotionEvent event) {
    // int x = (int)event.getX();
    //int y = (int)event.getY();
    int x = (int) event.getRawX();
    int y = (int) event.getRawY();
    //sharedPreferences = getSharedPreferences("CheckSharing",Context.MODE_PRIVATE);
    SharedPreferences.Editor editor = sharedPreferences.edit();
    editor.putInt("x", x);
    editor.putInt("y", y);
    editor.apply();
    MyCanvas.changeGravity();

    return false;
}

}

Answer 1

有我的问题。 每次发生触摸事件时，我都试图调用我的方法，这是我们无法做到的，因为当您拖动鼠标时，实际上会发生数千个（可能更多）触摸事件。

尝试从代码中理解。在主要活动中，我们有我们的 onTouch 事件侦听器，它调用 changeGravity() 方法，该方法又调用 calcDist() 和 setGravity() （来自 calcDist() ）。所以产生了很多垃圾，因此 GC 开始发挥作用，它暂停了应用程序，一切似乎都挂了。

解决方案 - 只需将 calcDist() 调用放在线程内，因此无论重力如何，都将在 10 毫秒内生效。与我们从 changeGravity() 方法调用时发生的情况相比，这是我们的模拟器和手机能够做到的。