使按钮不可见 5 秒

Question

目标：
当您启动应用程序时，按钮应该在 5 秒后可见。

In order words, Start the app -> Hide a button -> Wait 5 seconds -> Display the button

问题：
代码无效，我缺少哪一部分？

信息：
*我是 android 的新手，这是我尝试的

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Button button2 = (Button) findViewById(R.id.btn_test);
        button2.setVisibility(GONE);
        new Thread(new Runnable() {
            @Override
            public void run() {
                try{
                    //dummy delay for 5 second
                    Thread.sleep(5000);
                }
                catch (InterruptedException e){
                    e.printStackTrace();
                }
                runOnUiThread(new Runnable() { //resetting the visibility of the button
                    @Override
                    public void run() {

                        //manipulating UI components from outside of the UI Thread require a call to runOnUiThread
                        button2.setVisibility(VISIBLE);
                    }
                });
            }
        }).start();
    }
}

任何帮助将不胜感激谢谢

xml android清单

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.jfdimarzio.labb3">

    <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>

activity_main xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 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="com.jfdimarzio.labb3.MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/btn_test"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button"
        android:visibility="visible"
        tools:layout_editor_absoluteX="16dp"
        tools:layout_editor_absoluteY="16dp" />

</android.support.constraint.ConstraintLayout>

Answer 1

好像你错过了setContentView..先解决这个问题..

setContentView(R.layout.main_activity);

不要使用 Thread sleep。使用 handler post delayed 代替..

Handler handler = new Handler();
button2.setVisibility(View.GONE);
Runnable runnable = new Runnable() {
    @Override
    public void run() {
        button2.setVisibility(View.VISIBLE);
    }
}
// run runnable after 5 seconds
handler.postDelayed(runnable, 5000);

Answer 2

无需动作动画即可轻松制作动画。设置duration即可，动画结束后监听器会显示

buttonvVew.setVisibility(View.GONE);

buttonView.animate()
      .setDuration(5000)
      .setListener(new AnimatorListenerAdapter() {
        @Override
        public void onAnimationEnd(Animator animation) {
          super.onAnimationEnd(animation);
          buttonView.setVisibility(View.visible);
        }
});

Answer 3

试试这个

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main.xml);
        Button button2 = (Button) findViewById(R.id.btn_test);
        button2.setVisibility(GONE);
        button2.postDelayed(new Runnable() {
            public void run() {
                button2.setVisibility(View.VISIBLE);
            }
        }, 5000);
    }
}

使按钮不可见 5 秒

Make button invisible for 5 seconds

android

android-animation

android-button