Question

Hy先生，我很快就开始研究android，而且我遇到了setText方法的问题。我搜索了一个答案，没有任何结果。

这是一个我点击按钮时调用的活动，名称和电子邮件到达这个新活动，唯一的问题是当我尝试设置TextView的文本时我得到一个NPE。

package marcus.descubra_se;

import android.support.v7.app.ActionBarActivity;
import android.support.v4.app.Fragment;
import android.content.Intent;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;


public class ResultadoActivity extends ActionBarActivity {
static TextView tvnome;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Intent it = getIntent();
    String nome = "";
    String email = "";
    if(it != null){
        Bundle params = it.getExtras();
        if(params != null){
            nome = params.getString("nome");
            email = params.getString("email");
        }
    }
    Toast.makeText(this, nome, Toast.LENGTH_LONG).show();
    Toast.makeText(this, email, Toast.LENGTH_LONG).show();

    setContentView(R.layout.activity_resultado);
    tvnome = (TextView)findViewById(R.id.textView1);
    tvnome.setText(nome);

    // Define que o conteúdo exibido pela tela é o campo que
    // irá exibir o texto.
    //tvnome.setText(nome);
/*      TextView tvemail = (TextView) findViewById(R.id.textView5);
    tvemail.setText(email);

*/      setContentView(R.layout.activity_resultado);
    if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction().add(R.id.container, new PlaceholderFragment()).commit();
    }
}
public void voltar(View v){
    finish();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {

    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.resultado, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

/**
 * A placeholder fragment containing a simple view.
 */
public static class PlaceholderFragment extends Fragment {

    public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_resultado,
                container, false);
        return rootView;
    }
}

}

这是xml文件：

<Button
    android:id="@+id/button1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_centerHorizontal="true"
    android:layout_marginBottom="34dp"
    android:onClick="voltar"
    android:text="@string/voltar" />

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentTop="true"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="110dp"
    android:text="@string/abc_action_mode_done"
    android:textAppearance="?android:attr/textAppearanceLarge" />

</RelativeLayout>

这是logcat：

07-01 11:25:52.991: D/dalvikvm(1412): GC_FOR_ALLOC freed 80K, 8% free 2926K/3164K, paused 54ms, total 59ms
07-01 11:25:53.130: D/gralloc_goldfish(1412): Emulator without GPU emulation detected.
07-01 11:26:43.180: D/AndroidRuntime(1412): Shutting down VM
07-01 11:26:43.180: W/dalvikvm(1412): threadid=1: thread exiting with uncaught exception (group=0x41465700)
07-01 11:26:43.250: E/AndroidRuntime(1412): FATAL EXCEPTION: main
07-01 11:26:43.250: E/AndroidRuntime(1412): java.lang.RuntimeException: Unable to start activity ComponentInfo{marcus.descubra_se/marcus.descubra_se.ResultadoActivity}: java.lang.NullPointerException
07-01 11:26:43.250: E/AndroidRuntime(1412):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211)
07-01 11:26:43.250: E/AndroidRuntime(1412):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
07-01 11:26:43.250: E/AndroidRuntime(1412):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
07-01 11:26:43.250: E/AndroidRuntime(1412):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
07-01 11:26:43.250: E/AndroidRuntime(1412):     at android.os.Handler.dispatchMessage(Handler.java:99)
07-01 11:26:43.250: E/AndroidRuntime(1412):     at android.os.Looper.loop(Looper.java:137)
07-01 11:26:43.250: E/AndroidRuntime(1412):     at android.app.ActivityThread.main(ActivityThread.java:5103)
07-01 11:26:43.250: E/AndroidRuntime(1412):     at java.lang.reflect.Method.invokeNative(Native Method)
07-01 11:26:43.250: E/AndroidRuntime(1412):     at java.lang.reflect.Method.invoke(Method.java:525)
07-01 11:26:43.250: E/AndroidRuntime(1412):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
07-01 11:26:43.250: E/AndroidRuntime(1412):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
07-01 11:26:43.250: E/AndroidRuntime(1412):     at dalvik.system.NativeStart.main(Native Method)
07-01 11:26:43.250: E/AndroidRuntime(1412): Caused by: java.lang.NullPointerException
07-01 11:26:43.250: E/AndroidRuntime(1412):     at marcus.descubra_se.ResultadoActivity.onCreate(ResultadoActivity.java:36)
07-01 11:26:43.250: E/AndroidRuntime(1412):     at android.app.Activity.performCreate(Activity.java:5133)
07-01 11:26:43.250: E/AndroidRuntime(1412):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
07-01 11:26:43.250: E/AndroidRuntime(1412):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)
07-01 11:26:43.250: E/AndroidRuntime(1412):     ... 11 more

希望有人能帮助我！提前谢谢！

新版本的SDK不能设置TextView的Text（）

0 个答案: