TextViewTimberDebugTree.java

import android.os.Handler;
import android.widget.TextView;

import timber.log.Timber;

public class TextViewTimberDebugTree extends Timber.DebugTree {

    private final static long UNINITIALIZED_DEBUG_START_TIME = -1;

    private TextView textView;
    private Handler handler;
    private long debugStartTime = UNINITIALIZED_DEBUG_START_TIME;

    public TextViewTimberDebugTree(TextView textView, Handler handler) {
        this.textView = textView;
        this.handler = handler;
    }

    @Override
    protected void log(int priority, final String tag, final String message, Throwable t) {

        final long time = this.getTime();

        this.handler.post(new Runnable() {
            @Override
            public void run() {
                TextViewTimberDebugTree.this.textView.append(String.format("%d %s %s\n", time, tag, message));
            }
        });
    }

    @Override
    protected String createStackElementTag(StackTraceElement element) {
        String className = super.createStackElementTag(element);
        return String.format("%s.%s", className, element.getMethodName());
    }

    private long getTime() {
        if (this.debugStartTime == UNINITIALIZED_DEBUG_START_TIME) {
            this.debugStartTime = System.currentTimeMillis();
        }
        return System.currentTimeMillis() - this.debugStartTime;
    }
}