我正在尝试创建一个计时器,每分钟后它可以在文本视图中显示剩余时间,但是我一直无法成功。时间没有出现,也没有任何错误提示。
以下是我的代码:
package com.timer;
import android.os.Bundle;
import android.os.CountDownTimer;
import android.app.Activity;
import android.view.Menu;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity {
TextView tv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tv = (TextView) findViewById(R.id.tv);
CountDownTimer timer = new CountDownTimer(30000, 1000) {
public void onTick(long millisUntilFinished) {
int seconds = (int) (millisUntilFinished / 1000);
tv.setText("seconds remaining: " + String.valueOf(seconds));
}
public void onFinish() {
tv.setText("Finished!!");
}
};
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
以下是我的主要XML布局:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<TextView
android:id="@+id/tv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/hello_world" />
</RelativeLayout>