how to set different onclicklisteners on same button click?

Issue

I am implementing a timer in android with one text view and one button for start/stop.

How do I set register different events on clicklistener of the same button, such that when it is clicked the first time it will start a timer and when clicked a second time it will stop the timer and report the time between events? I am implementing a timer in android with one text view and one button for start/stop.

How do I set register different events on clicklistener of the same button, such that when it is clicked the first time it will start a timer and when clicked a second time it will stop the timer and report the time between events?

Edit1

what i did is,

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_depth);
    findViewById(R.id.btn).setOnClickListener(this);

}
boolean showingFirst = true;
public void generate(View view){

    if(showingFirst){
        long startTime = System.currentTimeMillis();
        showingFirst = false;
    }else{
        long difference = System.currentTimeMillis() - startTime;
        showingFirst = true;
        TextView myText = (TextView)findViewById(R.id.tv);
        myText.setText(String.valueOf(difference));
    }

}

but since long starttime is started in if when the control enters else loop it shows cannot resolve symbol 'startTime'

please help and special thanks to eliamyro

Solution

You can do it using a global boolean isStart and start or stop the timer depending on the value of the isStart.

btn.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        if (isStart) {
            // Stop timer
            isStart = false;
        } else {
            // Start timer
            isStart = true;
        }
    }
});

Answered By - eliamyro