小编Tha*_*son的帖子

这没有任何意义,我收到一个错误,说setOnClickListener不能应用于MainActivity.但我做了其他项目,我从来没有遇到过这个问题.这是怎么回事？

public class MainActivity extends ActionBarActivity {

Button button;

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


    button = ((Button) findViewById(R.id.button));

    button.setOnClickListener(this);

}

当我运行我的程序时,我没有遇到任何问题.当我尝试生成签名的apk时,我被告知getDefaultProguardFile无法解析.我怎样才能解决这个问题.这是代码.

apply plugin: 'com.android.application'

android {
    compileSdkVersion 21
    buildToolsVersion "21.1.2"

    defaultConfig {
        applicationId "com.dose.apps.brainnoodles"
        minSdkVersion 8
        targetSdkVersion 21
        versionCode 13
        versionName "2.13"
    }
    buildTypes {
        release {
            //apply plugin: 'idea'
            minifyEnabled true
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:22.0.0'
    compile files('libs/InMobi-4.5.3.jar')
}

这是被问到的堆栈跟踪

Warning:android.support.v4.view.accessibility.AccessibilityNodeInfoCompatApi22: can't find referenced method 'void setTraversalAfter(android.view.View,int)' in library class android.view.accessibility.AccessibilityNodeInfo
Warning:android.support.v4.media.session.MediaSessionCompatApi22: can't find referenced method 'void setRatingType(int)' in library class android.media.session.MediaSession
Warning:android.support.v4.view.accessibility.AccessibilityNodeInfoCompatApi22: can't find referenced method 'android.view.accessibility.AccessibilityNodeInfo getTraversalBefore()' …

我正在尝试增加一个乒乓球游戏框架.我希望每次球与球拍接触时球的大小都会增加.

这是我的尝试.第一个代码块是我认为问题所在.第二个街区是全班.

public class PlayState extends State {
private Paddle paddleRight, paddleLeft;
private static final int PADDLE_WIDTH = 30;
private static final int PADDLE_HEIGHT = 60;

private Ball ball;

//bDiam stands for ball diameter

private static int bDiam = 10;

private int playerScore = 0;
private Font scoreFont;

@Override
public void init() {
    paddleLeft = new Paddle(0, 195, PADDLE_WIDTH, PADDLE_HEIGHT);
    paddleRight = new Paddle(785, 195, PADDLE_WIDTH, PADDLE_HEIGHT);
    scoreFont = new Font("SansSerif", Font.BOLD, 25);
    ball = new Ball(300, 200, bDiam, bDiam); …

这是一本书中的练习代码,我正在学习try/catch语句.

显示的第一种方法要求load方法检索两个图像.此代码中的错误是资源文件中第一个img的名称称为"welcome.png",但正如您所看到的,它显示为"welcomee.png"(欢迎结束时的额外e).当我运行代码时,它不会打印出catch语句中的代码.它确实显示了堆栈跟踪(因为无论如何都会这样做),但它不会打印出"读取时出错:文件名".为什么是这样？

   public class Resources {

    public static BufferedImage welcome, iconimage;

    public static void load() {
        welcome = loadImage("welcomee.png");
        iconimage = loadImage("iconimage.png");
    }

    private static AudioClip loadSound(String filename) {
        URL fileURL = Resources.class.getResource("/resources/" + filename);
        return Applet.newAudioClip(fileURL);
    }

    private static BufferedImage loadImage(String filename) {
        BufferedImage img = null;
        try {
            img = ImageIO.read(Resources.class.getResourceAsStream("/resources/" + filename));
        } catch (IOException e) {
            System.out.println("Error while reading: " + filename);
            e.printStackTrace();
        }
        return img;
    }
}