SystemClock.elapsedRealtimeからstartTimeを引いた時間を表示しています。
参考:https://developer.android.com/reference/android/os/SystemClock.html
リフェレンス
handler:A Handler allows you to send and process Message and Runnable objects associated with a thread’s MessageQueue. Each Handler instance is associated with a single thread and that thread’s message queue. When you create a new Handler, it is bound to the thread / message queue of the thread that is creating it — from that point on, it will deliver messages and runnables to that message queue and execute them as they come out of the message queue.
SimpleDateFormat:is a concrete class for formatting and parsing dates in a locale-sensitive manner. It allows for formatting (date -> text), parsing (text -> date), and normalization.
package self.stopwatchapp;
import android.icu.text.SimpleDateFormat;
import android.os.Handler;
import android.os.SystemClock;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import java.util.Locale;
public class MainActivity extends AppCompatActivity {
private long startTime;
private long elapsedTime = 0l;
private Handler handler = new Handler();
private Runnable updateTimer;
private Button startButton;
private Button stopButton;
private Button resetButton;
private TextView timerLabel;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
startButton = (Button) findViewById(R.id.startButton);
stopButton = (Button) findViewById(R.id.stopButton);
resetButton = (Button) findViewById(R.id.resetButton);
timerLabel = (TextView) findViewById(R.id.timerLabel);
setButtonState(true, false, false);
}
public void setButtonState(boolean start, boolean stop, boolean reset){
startButton.setEnabled(start);
stopButton.setEnabled(stop);
resetButton.setEnabled(reset);
}
public void startTimer(View view){
// starttime
startTime = SystemClock.elapsedRealtime(); //起動からの経過時間
// 現在の経過時間
// Handler -> Runnable -> UI
updateTimer = new Runnable(){
@Override
public void run() {
long t = SystemClock.elapsedRealtime() - startTime + elapsedTime;
SimpleDateFormat sdf = new SimpleDateFormat("mm:ss.SSS", Locale.US);
timerLabel.setText(sdf.format(t));
handler.removeCallbacks(updateTimer);
handler.postDelayed(updateTimer, 10);
}
};
handler.postDelayed(updateTimer, 10);
// button
setButtonState(false, true, false);
}
public void stopTimer(View view){
elapsedTime += SystemClock.elapsedRealtime() - startTime;
handler.removeCallbacks(updateTimer);
setButtonState(true, false, true);
}
public void resetTimer(View view) {
elapsedTime = 0l;
timerLabel.setText("00:00:000");
setButtonState(true, false, false);
}
}
