Simple Java / Android Profiler

README.md

#Usage

SimpleProfiler testProfiler = new SimpleProfiler("TestProfiler", true);
testProfiler.start();
Thread.sleep(300);
testProfiler.addStep("method A");
Thread.sleep(200);
testProfiler.addStep("method B");
Thread.sleep(700);
testProfiler.addStep("method C");
String result = testProfiler.finish();
System.out.print(result);

#Output

TestProfiler: {
[method A took 301ms]
[method B took 200ms]
[method C took 700ms]
}
TestProfiler took 1202ms to complete

SimpleProfiler.java

import java.util.ArrayList;

/**
 * Created by Michal Mlejnek <[email protected]> on 05/02/2018.
 */

public class SimpleProfiler {
    private String name;
    private final boolean enabled;
    private long beginTimestamp;
    private ArrayList<Step> steps = new ArrayList();
    private boolean finished;

    public SimpleProfiler(String name, boolean enabled) {
        this.enabled = enabled;
        if (enabled) {
            this.name = name;
        }
    }

    public void start() {
        this.beginTimestamp = System.currentTimeMillis();
    }

    public void addStep(String name) {
        if (enabled && this.beginTimestamp != 0 && !finished)
            steps.add(new Step(System.currentTimeMillis(), name));
    }

    public String finish() {
        if (enabled && this.beginTimestamp != 0) {
            finished = true;
            StringBuilder result = new StringBuilder(name + ": {\n");
            for (int i = 0; i < steps.size(); i++) {
                createStepString(result, i);
            }
            result.append("}\n").append(name).append(" took ")
                    .append(System.currentTimeMillis() - beginTimestamp)
                    .append("ms to complete");
            return result.toString();
        } else {
            return "Profiler [" + name + "] not enabled or not started";
        }
    }

    private void createStepString(StringBuilder result, int i) {
        Step previousStep = null;
        if (i > 0) {
            previousStep = steps.get(i - 1);
        }
        Step step = steps.get(i);
        String stepTime;
        if (previousStep != null) {
            long time = ((step.timestamp - beginTimestamp)
                    - (previousStep.timestamp - beginTimestamp));
            stepTime = "[" + step.name + " took " + time + "ms]";
        } else {
            long time = (step.timestamp - beginTimestamp);
            stepTime = "[" + step.name + " took " + time + "ms]";
        }
        stepTime += "\n";
        result.append(stepTime);
    }

    public class Step {
        private long timestamp;
        private String name;

        Step(long timestamp, String name) {
            this.timestamp = timestamp;
            this.name = name;
        }
    }
}