java - 秒表按钮在Android Studio中崩溃

祝大家开心。

我一直在尝试使用Chronometer函数制作一个秒表应用程序，这是我的第一个应用程序。问题是，当我单击“开始”按钮(应用程序在平板电脑上运行时)时，崩溃了。情况与其他情况相似。

我不确定如何解决此问题，非常感谢您的帮助。

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">

<FrameLayout
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_alignParentStart="true"
    android:layout_alignParentTop="true">


    <ImageView
        android:id="@+id/body"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:srcCompat="@color/colorPrimaryDark" />

    <LinearLayout
        android:id="@+id/navcon"
        android:layout_width="match_parent"
        android:layout_height="92dp"
        android:orientation="vertical">

        <ImageView
            android:id="@+id/navbar"
            android:layout_width="match_parent"
            android:layout_height="80dp"
            android:background="@color/colorPrimary" />

    </LinearLayout>

    <LinearLayout
        android:id="@+id/navtextcon"
        android:layout_width="match_parent"
        android:layout_height="80dp"
        android:orientation="vertical">

        <TextView
            android:id="@+id/navtext"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:gravity="center"
            android:text="rocket.studios"
            android:textColor="@android:color/white"
            android:textSize="24sp"
            android:textStyle="bold" />
    </LinearLayout>

</FrameLayout>

<LinearLayout
    android:id="@+id/chronocon"
    android:layout_width="match_parent"
    android:layout_height="95dp"
    android:layout_alignParentStart="true"
    android:layout_alignParentTop="true"
    android:layout_marginTop="78dp"
    android:orientation="vertical">

    <Chronometer
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:gravity="center"
        android:textColor="@android:color/white"
        android:textSize="60sp"
        android:textStyle="bold" />
</LinearLayout>

<LinearLayout
    android:id="@+id/startbcon"
    android:layout_width="match_parent"
    android:layout_height="118dp"
    android:layout_alignParentStart="true"
    android:layout_alignParentTop="true"
    android:layout_marginTop="155dp"
    android:orientation="vertical"
    android:padding="20dp">

    <Button
        android:id="@+id/startb"
        android:layout_width="match_parent"
        android:layout_height="68dp"
        android:background="@color/colorPrimary"
        android:text="@string/start"
        android:textColor="@android:color/white"
        android:textSize="24sp"
        android:textStyle="bold" />
</LinearLayout>

<LinearLayout
    android:id="@+id/stopbcon"
    android:layout_width="match_parent"
    android:layout_height="118dp"
    android:layout_alignParentStart="true"
    android:layout_centerVertical="true"
    android:orientation="vertical"
    android:padding="20dp">

    <Button
        android:id="@+id/stopb"
        android:layout_width="match_parent"
        android:layout_height="68dp"
        android:background="@color/colorPrimary"
        android:text="@string/stop"
        android:textColor="@android:color/white"
        android:textSize="24sp"
        android:textStyle="bold" />
</LinearLayout>

<LinearLayout
    android:id="@+id/resetbcon"
    android:layout_width="match_parent"
    android:layout_height="118dp"
    android:layout_alignParentBottom="true"
    android:layout_alignParentStart="true"
    android:layout_marginBottom="158dp"
    android:orientation="vertical"
    android:padding="20dp">

    <Button
        android:id="@+id/resetb"
        android:layout_width="match_parent"
        android:layout_height="68dp"
        android:background="@color/colorPrimary"
        android:text="@string/reset"
        android:textColor="@android:color/white"
        android:textSize="24sp"
        android:textStyle="bold" />
</LinearLayout>

MainActivity.java:

package testing.ezekieralt.com.stopwatcher;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.ButtonBarLayout;
import android.view.View;
import android.widget.Button;
import android.widget.Chronometer;
import android.os.SystemClock;

//chronometer is...guess it

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

private Chronometer chronometer;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    findViewById(R.id.startb).setOnClickListener(this);
    findViewById(R.id.resetb).setOnClickListener(this);
    findViewById(R.id.stopb).setOnClickListener(this);
    chronometer = findViewById(R.id.chronometer);

}


@Override
public void onClick(View v) {
    switch(v.getId()){
        case R.id.stopb:
            chronometer.stop();
            break;
        case R.id.startb:
            chronometer.setBase(SystemClock.elapsedRealtime());
            chronometer.start();
            break;
        case R.id.resetb:
            chronometer.setBase(SystemClock.elapsedRealtime());
            break;

    }


}
}

AndroidManifest.xml:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="testing.ezekieralt.com.stopwatcher">

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

</manifest>

最佳答案

您没有将id添加到Chronometer中。将ID添加到Chronometer

<Chronometer
    android:id="@+id/chronometer"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:gravity="center"
    android:textColor="@android:color/white"
    android:textSize="60sp"
    android:textStyle="bold" />