一个空指针异常，求解决

极品捉妖师 2014-03-28 12:09:57

package com.example.checkapplication;
import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.app.ActivityManager;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;
public class MainActivity extends Activity {
private ActivityManager mActivityManager;
private int intGetTastCounter = 30;
public Button mButton1;
public ListView mListView1;
public ArrayList arylistTask;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mButton1 = (Button)findViewById(R.id.button1);
mListView1 = (ListView)findViewById(R.id.list);
mButton1.setOnClickListener(new Button.OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
try{
//j对象向系统取得ACTIVITY_SERVICE
mActivityManager = (ActivityManager)
MainActivity.this.getSystemService(ACTIVITY_SERVICE);
arylistTask = new ArrayList<String>();
List<ActivityManager.RunningTaskInfo>mRunningTasks =
mActivityManager.getRunningTasks(intGetTastCounter);
int i = 1;
for(ActivityManager.RunningTaskInfo amTask:mRunningTasks){
arylistTask.add(""+(i++)+": "+
amTask.baseActivity.getClassName()+"(ID=" + amTask.id +")");
}
ArrayAdapter aryAdapter1 = new ArrayAdapter<String>
(MainActivity.this,R.layout.simple_list_item_1,arylistTask);
if(aryAdapter1.getCount()==0){
mMakeTextToast(
getResources().getText
(R.string.str_err_no_running_task).toString(),true);

}
else {
mListView1.setAdapter(aryAdapter1);
}

}catch(SecurityException e){
mMakeTextToast(
getResources().getText(R.string.str_err_permission).toString(),true
);
}
}

private void mMakeTextToast(String str, boolean islong) {
// TODO Auto-generated method stub
if(islong==true){
Toast.makeText(MainActivity.this,str, Toast.LENGTH_LONG).show();
}
else{
Toast.makeText(MainActivity.this,str, Toast.LENGTH_SHORT).show();
}
}

});
mListView1.setOnItemSelectedListener
(new ListView.OnItemSelectedListener(){

@Override
public void onItemSelected(AdapterView<?> parent, View v,
int id, long arg3) {
// TODO Auto-generated method stub
mMakeTextToast(arylistTask.get(id).toString(),false);

}

private void mMakeTextToast(String str, boolean islong) {
// TODO Auto-generated method stub
if(islong==true){
Toast.makeText(MainActivity.this,str, Toast.LENGTH_LONG).show();
}
else{
Toast.makeText(MainActivity.this,str, Toast.LENGTH_SHORT).show();
}
}

@Override
public void onNothingSelected(AdapterView<?> parent) {
// TODO Auto-generated method stub

}

});

}

}

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