的錯誤,我有這樣的代碼:獲取有關TabHost
public void onResume()
{
super.onResume();
tabHost=getTabHost();
tabHost.addTab(tabHost.newTabSpec("tab1").setIndicator("All").setContent(new Intent(this, AllTest.class)
.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP)));
tabHost.addTab(tabHost.newTabSpec("tab2").setIndicator("Attempted").setContent(
new Intent(this, Att_Test.class).addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP)));
tabHost.addTab(tabHost.newTabSpec("tab3").setIndicator("Unattempted").setContent(
new Intent(this, SyncAlbum.class).addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP)));
tabHost.addTab(tabHost.newTabSpec("tab4").setIndicator("New").setContent(
new Intent(this, SyncTest.class).addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP)));
tabHost.getTabWidget().getChildAt(0).getLayoutParams().height =35;
tabHost.getTabWidget().getChildAt(1).getLayoutParams().height =35;
tabHost.getTabWidget().getChildAt(2).getLayoutParams().height =35;
tabHost.getTabWidget().getChildAt(3).getLayoutParams().height =35;
if(tabbed.equals("Att_Test")){
tabHost.setCurrentTab(1);
}
else
{
tabHost.setCurrentTab(0);
}
}
方法的序列.onResume又被稱爲像這樣經過:
tabHost.clearAllTabs();
onResume();
此代碼工作正常時,用戶在第一個選項卡,但當我們試圖調用的onResume方法在其他標籤中,給出了一個空指針:
03-27 18:48:05.833: E/AndroidRuntime(18564): FATAL EXCEPTION: main
03-27 18:48:05.833: E/AndroidRuntime(18564): java.lang.NullPointerException
03-27 18:48:05.833: E/AndroidRuntime(18564): at android.widget.TabWidget.setCurrentTab(TabWidget.java:339)
03-27 18:48:05.833: E/AndroidRuntime(18564): at android.widget.TabWidget.focusCurrentTab(TabWidget.java:363)
03-27 18:48:05.833: E/AndroidRuntime(18564): at android.widget.TabHost.setCurrentTab(TabHost.java:320)
03-27 18:48:05.833: E/AndroidRuntime(18564): at android.widget.TabHost.addTab(TabHost.java:213)
03-27 18:48:05.833: E/AndroidRuntime(18564): at com.cuelearn.main.TestTab.onResume(TestTab.java:65)
03-27 18:48:05.833: E/AndroidRuntime(18564): at com.cuelearn.main.TestTab$3$1.onClick(TestTab.java:209)
03-27 18:48:05.833: E/AndroidRuntime(18564): at com.android.internal.app.AlertController$AlertParams$3.onItemClick(AlertController.java:874)
03-27 18:48:05.833: E/AndroidRuntime(18564): at android.widget.AdapterView.performItemClick(AdapterView.java:284)
03-27 18:48:05.833: E/AndroidRuntime(18564): at android.widget.ListView.performItemClick(ListView.java:3382)
03-27 18:48:05.833: E/AndroidRuntime(18564): at android.widget.AbsListView$PerformClick.run(AbsListView.java:1696)
03-27 18:48:05.833: E/AndroidRuntime(18564): at android.os.Handler.handleCallback(Handler.java:587)
03-27 18:48:05.833: E/AndroidRuntime(18564): at android.os.Handler.dispatchMessage(Handler.java:92)
03-27 18:48:05.833: E/AndroidRuntime(18564): at android.os.Looper.loop(Looper.java:123)
請幫我解決這個疑難問題是新手?
編輯所有代碼
這些是其他的方法:
void setupView()
{
Button name=(Button)findViewById(R.id.name);
name.setText(login.A_students.STUDENT_NAME);
name.setOnClickListener(logout);
((Button)findViewById(R.id.cuelearn)).setOnClickListener(cuelearnClicked);
courses course_db= new courses(this);
course_db.open();
Cursor s=course_db.getrecord(CourseId);
coursename=(Button)findViewById(R.id.blank);
setCourseName(s.getString(2));
coursename.setOnClickListener(course_nameClicked);
}
void setCourseName(String courseid)
{
coursename.setText(courseid);
}
private OnClickListener logout = new OnClickListener(){
@Override
public void onClick(View v) {
AlertDialog.Builder builder = new AlertDialog.Builder(TestTab.this);
builder.setMessage("Are you sure you want to Logout?")
.setCancelable(false)
.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
finish();
startActivity(new Intent(TestTab.this,com.cuelearn.main.login.class));
}
})
.setNeutralButton("No", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
dialog.cancel();
}
});
AlertDialog alert = builder.create();
alert.show();
}};
private OnClickListener cuelearnClicked = new OnClickListener(){
@Override
public void onClick(View v) {
// TODO OnClickListener()
Intent intent = new Intent(TestTab.this, cuelearntwo.class)
第二個選項卡代碼
公共類Att_Test延伸活動{
private testpapertable testpaper_db;
private courses courses_db;
private coursesclass A_courses=new coursesclass();
ArrayList<String> courseid;
ArrayList<String> courseName;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
TestTab.tabbed="Att_Test";
requestWindowFeature(Window.FEATURE_NO_TITLE);
System.out.println(TestTab.CourseId+"ALLTE");
setContentView(R.layout.alltest);
showAllTestPapers();
}
將所有代碼從您的** onResume **移動到** onCreate **方法 – waqaslam 2012-03-27 13:30:38