/*
 * Catch out-of-memory errors with an Thread.UncaughtExceptionHandler
 * and generate an hprof heap dump.
 */
import android.os.Debug;

import java.io.IOException;
import java.util.ArrayList;

public class HeapDump {
    public static void test() {
        Catcher catcher = new Catcher();
        catcher.setAsDefaultHandler();

        runOutOfMemory();
    }

    static void runOutOfMemory() {
        ArrayList<byte[]> al = new ArrayList<byte[]>();

        while (true) {
            al.add(new byte[1024*1024]);
        }
    }
}

class Catcher implements Thread.UncaughtExceptionHandler {
    Thread.UncaughtExceptionHandler mPrevHandler;

    public void setAsDefaultHandler() {
        Thread.UncaughtExceptionHandler oldHandler =
            Thread.getDefaultUncaughtExceptionHandler();
        if (oldHandler != null && mPrevHandler == oldHandler) {
            throw new RuntimeException("don't call this twice");
        }

        mPrevHandler = oldHandler;
        Thread.setDefaultUncaughtExceptionHandler(this);
    }

    public void uncaughtException(Thread t, Throwable e) {
        System.out.println("caught! " + e);

        if (e instanceof OutOfMemoryError) {
            // App requires WRITE_EXTERNAL_STORAGE permission to
            // write to /sdcard.  Could also write to the app-private
            // data area.
            try {
                Debug.dumpHprofData("/sdcard/dump.hprof");
            } catch (IOException ioe) {
                System.err.println("hprof dump failed");
            }
        }

        if (mPrevHandler != null) {
            System.out.println("calling previous handler");
            mPrevHandler.uncaughtException(t, e);
        }

        // In an Android app, the system crash-catcher will kill the
        // app after asking the system to display the "force close"
        // dialog, so we shouldn't get here.  If you remove the
        // mPrevHandler call, it would be wise to exit() here.
    }
}