Question

我正在尝试创建一个RSS应用程序，我将在其中打开一个带有WebView相关文章的活动。我使用Intent putExtra可能不起作用......任何人都有解决方案的建议吗？

谢谢！

ShowNews.java

import android.app.Activity;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;

public class ShowNews extends Activity{
    public void onCreate(Bundle bundle)
    {
        super.onCreate(bundle);
        setContentView(R.layout.show_news);

        String oneNews = null;
        String nTitle = null;
        String nDesc = null;
        String nDate = null;
        String nLink = null;


        Intent i = getIntent();

        if(i != null)
        {
            Bundle b = i.getBundleExtra("BUNDLE.VISA.SEN.INTENT");
            if(b == null)
            {
                oneNews = "Fel bundle?";
            } else {
                nTitle = b.getString("title");
                nDesc = b.getString("description");
                nDate = b.getString("pubdate");
                nLink = b.getString("link");
            }
        } else {
            oneNews = "Information Not Found.";
        }

        TextView tTitle = (TextView)findViewById(R.id.title);
        TextView tDesc = (TextView)findViewById(R.id.desc);
        TextView tDate = (TextView)findViewById(R.id.pubdate);
        TextView tLink = (TextView)findViewById(R.id.link);

        tTitle.setText(nTitle);
        tDesc.setText(nDesc);
        tDate.setText(nDate);
        tLink.setText(nLink);
        final String iLink = nLink;

        tLink.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent i = new Intent(ShowNews.this, Browser.class);
                i.putExtra("link", String.valueOf(iLink));
                startActivity(i);
            }
        });
    }
}

Browser.java

import android.os.Bundle;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.util.Log;
import android.view.KeyEvent;
import android.view.Menu;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.content.Intent;


@SuppressLint("SetJavaScriptEnabled")
public class Browser extends Activity {

    private WebView mWebView;
    //String i = getIntent().getStringExtra("link");

    Bundle extras = getIntent().getExtras(); 

    String URLEN = extras.getString("link");
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.web_view);

        mWebView = (WebView)findViewById(R.id.webview);
        mWebView.getSettings().setJavaScriptEnabled(true);
        mWebView.loadUrl(URLEN);
        mWebView.setWebViewClient(new WebClient());

    }

    public class WebClient extends WebViewClient{
        @Override
        public boolean shouldOverrideUrlLoading(WebView webview, String url)
        {
            webview.loadUrl(url);
            return true;
        }
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {

        if ((keyCode == KeyEvent.KEYCODE_BACK) && mWebView.canGoBack()) {
            mWebView.goBack();
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

}

错误

    01-12 22:55:53.328: E/AndroidRuntime(12532): FATAL EXCEPTION: main
01-12 22:55:53.328: E/AndroidRuntime(12532): Process: com.example.com.raj.rss, PID: 12532
01-12 22:55:53.328: E/AndroidRuntime(12532): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.com.raj.rss/com.example.com.raj.rss.Browser}: java.lang.NullPointerException
01-12 22:55:53.328: E/AndroidRuntime(12532):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2124)
01-12 22:55:53.328: E/AndroidRuntime(12532):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2248)
01-12 22:55:53.328: E/AndroidRuntime(12532):    at android.app.ActivityThread.access$800(ActivityThread.java:138)
01-12 22:55:53.328: E/AndroidRuntime(12532):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1199)
01-12 22:55:53.328: E/AndroidRuntime(12532):    at android.os.Handler.dispatchMessage(Handler.java:102)
01-12 22:55:53.328: E/AndroidRuntime(12532):    at android.os.Looper.loop(Looper.java:136)
01-12 22:55:53.328: E/AndroidRuntime(12532):    at android.app.ActivityThread.main(ActivityThread.java:5050)
01-12 22:55:53.328: E/AndroidRuntime(12532):    at java.lang.reflect.Method.invokeNative(Native Method)
01-12 22:55:53.328: E/AndroidRuntime(12532):    at java.lang.reflect.Method.invoke(Method.java:515)
01-12 22:55:53.328: E/AndroidRuntime(12532):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1264)
01-12 22:55:53.328: E/AndroidRuntime(12532):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1080)
01-12 22:55:53.328: E/AndroidRuntime(12532):    at dalvik.system.NativeStart.main(Native Method)
01-12 22:55:53.328: E/AndroidRuntime(12532): Caused by: java.lang.NullPointerException
01-12 22:55:53.328: E/AndroidRuntime(12532):    at com.example.com.raj.rss.Browser.<init>(Browser.java:20)
01-12 22:55:53.328: E/AndroidRuntime(12532):    at java.lang.Class.newInstanceImpl(Native Method)
01-12 22:55:53.328: E/AndroidRuntime(12532):    at java.lang.Class.newInstance(Class.java:1208)
01-12 22:55:53.328: E/AndroidRuntime(12532):    at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
01-12 22:55:53.328: E/AndroidRuntime(12532):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2115)
01-12 22:55:53.328: E/AndroidRuntime(12532):    ... 11 more

Answer 1

您无法在类级别使用意图，您必须在onCreate中使用它（以便在使用之前运行onCreate）。

public class Browser extends Activity {

    private WebView mWebView;

    Bundle extras; 
    String URLEN;

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

        extras = getIntent().getExtras(); 
        URLEN = extras.getString("link");

        mWebView = (WebView)findViewById(R.id.webview);
        mWebView.getSettings().setJavaScriptEnabled(true);
        mWebView.loadUrl(URLEN);
        mWebView.setWebViewClient(new WebClient());

    }

    // .. the rest of the class
}

Answer 2

将其移至onCreate（）

 Bundle extras = getIntent().getExtras(); 
 String URLEN = extras.getString("link");

至少onCreate()之前，您无法访问该意图。

Intent putExtra，NullPointerException

2 个答案: