java错误打开意图
调用其他意图时出错
我无法解决这个问题,我需要尽快解决它,以完成我的工作当然是完成课程。提前感谢您的帮助
06-09 14:41:28.902: E/AndroidRuntime(769): FATAL EXCEPTION: main
06-09 14:41:28.902: E/AndroidRuntime(769): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{br.com.projeto_tcc/br.com.projeto_tcc.view.EscolhaGUI}: java.lang.NullPointerException
06-09 14:41:28.902: E/AndroidRuntime(769):
at 安卓.app.ActivityThread.performLaunchActivity(ActivityThread.java:2106)
06-09 14:41:28.902: E/AndroidRuntime(769):
我的舱单
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:安卓="http://schemas.安卓.com/apk/res/安卓"
package="br.com.projeto_tcc"
安卓:versionCode="1"
安卓:versionName="1.0" >
<uses-sdk
安卓:minSdkVersion="8"
安卓:targetSdkVersion="17" />
<uses-permission 安卓:name="安卓.permission.BLUETOOTH_ADMIN"/>
<uses-permission 安卓:name="安卓.permission.BLUETOOTH"/>
<uses-permission 安卓:name="安卓.permission.WRITE_INTERNAL_STORAGE" />
<application
安卓:allowBackup="true"
安卓:icon="@drawable/ic_launcher"
安卓:label="@string/app_name"
安卓:theme="@style/AppTheme" >
<activity
安卓:name="br.com.projeto_tcc.view.NewPlayerGUI"
安卓:label="@string/app_name" >
<intent-filter>
<action 安卓:name="安卓.intent.action.MAIN" />
<category 安卓:name="安卓.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity 安卓:name="br.com.projeto_tcc.view.PlayerGUI"/>
<activity 安卓:name="br.com.projeto_tcc.view.OpcaoGUI"/>
<activity 安卓:name="br.com.projeto_tcc.view.JogoGUI"/>
<activity 安卓:name="br.com.projeto_tcc.view.EscolhaGUI"/>
<activity 安卓:name="br.com.projeto_tcc.bluetooth.Actv"/>
<activity 安卓:name="br.com.projeto_tcc.bluetooth.MainActivity"/>
</application>
</manifest>
我的班级
public class EscolhaGUI extends Activity {
Intent intent = new Intent(this, Actv.class);
Intent intent2 = new Intent(this, MainActivity.class);
@Override
protected void onCreate(Bundle savedInstanceState) {
try {
final Button btn_esp = (Button) findViewById(R.id.btn_esp);
final Button btn_conv = (Button) findViewById(R.id.btn_conv);
super.onCreate(savedInstanceState);
setContentView(R.layout.escolher);
btn_esp.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View arg0) {
finish();
startActivity(intent);
}
});
btn_conv.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View arg0) {
finish();
startActivity(intent2);
}
});
} catch (Exception e) {
AlertDialog alertDialog;
alertDialog = new AlertDialog.Builder(this).create();
alertDialog.setTitle("Erro");
alertDialog.setMessage("Este: ." + e);
alertDialog.show();
}
}
# 1 楼答案
您遇到的问题是,在调用
setContentView(R.layout.escolher)
之前正在检索这些按钮。因此,将对findViewById
的调用置于setContentView
之后,您的onCreate
方法应该如下所示:编辑: 如果您不太清楚我说的内容,请尝试调试。您可以打赌,两个按钮都将等于null,从而导致此行出现NPE:
正如logcat跟踪在此处所述: