android activity中new出的线程不会随着activity的finished而结束

如图所示：

我的代码如下

package com.hai;


import android.graphics.Bitmap;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.PersistableBundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;

import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.ImageRequest;
import com.android.volley.toolbox.Volley;

import java.io.File;

public class MyActivity extends AppCompatActivity {
    Button btn;
    ImageView iv;
    boolean run = true;
    int i = 1;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        final RequestQueue queue = Volley.newRequestQueue(this);
        File cacheDir = new File(getCacheDir(), "volley");
        Log.d("hhp", cacheDir.getAbsolutePath());
        btn = (Button) findViewById(R.id.btn1);
        iv = (ImageView) findViewById(R.id.image);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
//                requestImage(queue);
                testHandle();
                try {
                    Thread.sleep(2000);
//                    finish();
                    System.exit(0);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        });

    }

    private void requestImage(RequestQueue queue) {
        ImageRequest request = new ImageRequest("https://192.168.1.102:8080/tomcat.png", new Response.Listener<Bitmap>() {
            @Override
            public void onResponse(Bitmap bitmap) {
                iv.setImageBitmap(bitmap);

            }
        }, 0, 0, null, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError volleyError) {

            }
        });
        queue.add(request);
        new Thread(new Runnable() {
            @Override
            public void run() {

            }
        }).start();
    }

    void testHandle() {
        new Thread(new Runnable() {
            @Override
            public void run() {
                while (true) {
                    Log.d("hhp", "jskdjflksdjlfjsdsf双方的诉讼的风");
                }
            }
        }).start();
    }
}package com.hai;


impor