小编oue*_*lel的帖子

我一直在测试char铸件,我经历了这个:

public class Test {
    public static void main(String a[]) {
        final byte b1 = 1;
        byte b2 = 1;
        char c = 2;

        c = b1; // 1- Working fine
        c = b2; // 2 -Compilation error
    }
}

任何人都可以解释为什么当我在字节中添加最后一个时它在1中正常工作？

我的Android 3.1模拟器有些问题.我无法获取我的XML文件.

protected InputStream getInputStream() {
    try {

        return feedUrl.openConnection().getInputStream();
    } catch (IOException e) {
        throw new RuntimeException(e);
    }
}

这是错误跟踪:

08-07 22:34:26.657: ERROR/AndroidRuntime(563): Caused by: android.os.NetworkOnMainThreadException
08-07 22:34:26.657: ERROR/AndroidRuntime(563):     at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1077)
08-07 22:34:26.657: ERROR/AndroidRuntime(563):     at java.net.InetAddress.lookupHostByName(InetAddress.java:477)
08-07 22:34:26.657: ERROR/AndroidRuntime(563):     at java.net.InetAddress.getAllByNameImpl(InetAddress.java:277)
08-07 22:34:26.657: ERROR/AndroidRuntime(563):     at java.net.InetAddress.getAllByName(InetAddress.java:249)
08-07 22:34:26.657: ERROR/AndroidRuntime(563):     at org.apache.harmony.luni.internal.net.www.protocol.http.HttpConnection.<init>(HttpConnection.java:69)
08-07 22:34:26.657: ERROR/AndroidRuntime(563):     at org.apache.harmony.luni.internal.net.www.protocol.http.HttpConnection.<init>(HttpConnection.java:48)
08-07 22:34:26.657: ERROR/AndroidRuntime(563):     at org.apache.harmony.luni.internal.net.www.protocol.http.HttpConnection$Address.connect(HttpConnection.java:304)
08-07 22:34:26.657: ERROR/AndroidRuntime(563):     at org.apache.harmony.luni.internal.net.www.protocol.http.HttpConnectionPool.get(HttpConnectionPool.java:89)
08-07 22:34:26.657: ERROR/AndroidRuntime(563):     at org.apache.harmony.luni.internal.net.www.protocol.http.HttpURLConnectionImpl.getHttpConnection(HttpURLConnectionImpl.java:292)
08-07 22:34:26.657: ERROR/AndroidRuntime(563):     at org.apache.harmony.luni.internal.net.www.protocol.http.HttpURLConnectionImpl.makeConnection(HttpURLConnectionImpl.java:274)
08-07 22:34:26.657: ERROR/AndroidRuntime(563): …

我一直在尝试模拟ocjp 6测试.我问了一个问题,问问构造函数是否正确:

 1- public Test8(){}
 2- private void Test8(){}
 3- protected Test8(int k){}
 4- Test8(){}

正确答案是1和3.我不明白为什么4是不正确的.当我测试以下代码时:

public class Test8 {
    Test8() {}

    public Test8() {}

}

我有编译错误,但当我删除其中一个构造函数,如果编译没有任何问题.

有人可以帮我清理一下.