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我是新來的Android，我試圖運行一個應用程序（簡單的測試應用程序），但得到這個錯誤（我已經註冊了我在AndroidManifest.xml中的所有活動，我使用的是Android 1.0.2工作室java.lang.RuntimeException：無法實例化活動ComponentInfo，所有活動都在AndroidManifest.xml中註冊，不知道什麼是錯的
下面是一個應用程序的logcat的：
MainActivity 的01-03 20:34:24.128 17300-17300/com.example.temur.sherlocked D/AndroidRuntime﹕ Shutting down VM
01-03 20:34:24.134 17300-17300/com.example.temur.sherlocked E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.temur.sherlocked, PID: 17300
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.temur.sherlocked/com.example.temur.sherlocked.MainActivity}: java.lang.InstantiationException: com.example.temur.sherlocked.MainActivity
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2124)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2257)
at android.app.ActivityThread.access$800(ActivityThread.java:139)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1210)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5086)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
Caused by: java.lang.InstantiationException: com.example.temur.sherlocked.MainActivity
at java.lang.Class.newInstance(Class.java:1561)
at android.app.Instrumentation.newActivity(Instrumentation.java:1084)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2115)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2257)
at android.app.ActivityThread.access$800(ActivityThread.java:139)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1210)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5086)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Constructor.newInstance(Native Method)
at java.lang.Class.newInstance(Class.java:1559)
at android.app.Instrumentation.newActivity(Instrumentation.java:1084)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2115)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2257)
at android.app.ActivityThread.access$800(ActivityThread.java:139)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1210)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5086)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.Window.findViewById(int)' on a null object reference
at android.app.Activity.findViewById(Activity.java:1892)
at com.example.temur.sherlocked.MainActivity.<init>(MainActivity.java:43)
at java.lang.reflect.Constructor.newInstance(Native Method)
at java.lang.Class.newInstance(Class.java:1559)
at android.app.Instrumentation.newActivity(Instrumentation.java:1084)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2115)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2257)
at android.app.ActivityThread.access$800(ActivityThread.java:139)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1210)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5086)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
代碼
package com.example.temur.sherlocked;
import android.content.Intent;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.TextView;
public class MainActivity extends ActionBarActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, 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();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
TextView infoTextView = (TextView)findViewById(R.id.textViewAnswer);
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data){
super.onActivityResult(requestCode,resultCode,data);
if (requestCode==CHOOSE_THIEF){
if (resultCode==RESULT_OK){
String thiefName = data.getStringExtra(SecondActivity.THIEF);
infoTextView.setText(thiefName);
}else {
infoTextView.setText("");
}
}
}
static final private int CHOOSE_THIEF = 0;
public void onClick(View view) {
Intent questionIntent = new Intent(MainActivity.this, SecondActivity.class);
startActivityForResult(questionIntent,CHOOSE_THIEF);
}
}
請幫助我:)
主要原因是'NullPointerException：試圖調用虛擬方法'android.view.View android.view.Window.findViewById（int）'在空對象引用上。搜索一下，你可能會找到答案。 – Tom
你還沒有安裝'setContentView（R.layout.activity）;''onCreate'方法'' – SorryForMyEnglish
發佈你的代碼太多了......但很難知道問題 – Psypher