android - CountDownTimer

Question

我想在ProgressDialog中得到计数器、文本和图像。我设法得到了文本和图像，但很难得到计数器显示。我想得到这样的东西：

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所以我从上面找不到柜台了，有人能帮忙吗？

MainActivity.java

        TextView mTextView_timeCounter;

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

        StorageSingleton.getInstance().setString(null, null);

        progress = new ProgressDialog(this, R.layout.countdown);
        progress.setCancelable(false);

        //for displaying counter
        mTextView_timeCounter = (TextView) findViewById(R.id.myTimerTextView);

        progress = new ProgressDialog(this, R.layout.countdown);

        progress.setCancelable(false);

        progress.setIndeterminate(true);
        progress.setIndeterminateDrawable(getResources().getDrawable(R.drawable.timer_logo));


        new CountDownTimer(60000, 1000) {

            public void onTick(long millisUntilFinished) {
                long seconds = millisUntilFinished / 1000;
                String countdown = String.format("%02d", seconds / 60) + ":" + String.format("%02d", seconds % 60);
                progress.setMessage(countdown);

                progress.setContentView(R.layout.countdown);

                mTextView_timeCounter.setText(countdown);// <- this line causing error

            }

            public void onFinish() {
                progress.dismiss();
            }
        }.start();

        progress.show();

有错误：

PID: 31908 java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference这是由行引起的

mTextView_timeCounter.setText(countdown);，但我不知道为什么。请查找下面的代码

Countdown.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:clickable="false"
            android:padding="30dp"
            android:layout_margin="35dp"
            android:orientation="vertical"
            android:weightSum="1">


<TextView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:text="Test in Progress..."
    android:textColor="@color/sample12"
    android:textSize="@dimen/header_text"
    android:textStyle="bold"
    android:textAlignment="center"
    android:id="@+id/testInProgress"
    android:layout_alignParentTop="true"
    android:layout_centerHorizontal="true"
    android:layout_gravity="center_horizontal"/>

<ImageView
        android:id="@+id/imageView4"
        android:layout_width="260dp"
        android:layout_height="260dp"
        android:src="@drawable/timer_logo"
        android:clickable="false"
        android:contentDescription="hourglass"
        android:layout_below="@+id/textView14"
        android:layout_alignParentEnd="true"
        />

<TextView
    android:layout_width="91dp"
    android:layout_height="wrap_content"
    android:id="@+id/myTimerTextView"
    android:layout_gravity="center_horizontal"
    android:layout_weight="0.10"
    android:text=""/>

​

Answer 1

当应用程序尝试使用具有空值的对象引用时，将引发NullPointerException。

您应该传递视图对象。

progress.setContentView(R.layout.countdown);
mTextView_timeCounter = (TextView)progress.findViewById(R.id.myTimerTextView);
mTextView_timeCounter.setText(countdown);

Answer 2

更改为mTextView_timeCounter = (TextView) progress.findViewById(R.id.myTimerTextView);

您在活动布局中找到视图，而在倒计时中找到文本视图。