Question

我创建了一个ListView，它显示了使用ArrayList和ArrayAdapter的待办事项。当我单击一个任务时，它正在从待办任务列表中删除，并且被添加到另一个完成待办任务列表的ArrayList中。我想做的是，将任务添加到已完成的待办事项列表中，并使用不同的文本颜色。

我为完成的任务创建了另一个XML，但是我还需要获取文本颜色值以进行下一步比较。根据颜色，稍后我将添加要执行的任务和已完成的任务以及另一个列表，它们需要以不同的颜色显示。

当我在应用程序中单击“显示已完成的任务”时，我也尝试了覆盖getView方法以访问setter和getter方法，但它给了我一个例外（在text.setTextColor（Color.RED）；下面的行上）。 >

我想不通，希望有人帮我弄清楚：

Application Screenshot

public class MainActivity extends AppCompatActivity {

private DrawerLayout mainLayout;
private AlertDialog.Builder dialogBuilder, confirmBuilder;
private AlertDialog dialog, confirmDialog;
private ArrayList<String> todoList, completedList, allList;
private ArrayAdapter<String> todoAdapter,completedAdapter, allAdapter;
private ListView listView;
private TextView txt;
private boolean isCompletedJob;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    isCompletedJob=false;
    listView = findViewById(R.id.listView1);

    mainLayout = findViewById(R.id.drawer_layout); //FIND THE LAYOUT INCLUDING MAIN CONTENT AND NAVIGATION MENU

    dialogBuilder = new AlertDialog.Builder(this);  //CREATE A BUILDER TO CREATE A DIALOG
    dialogBuilder.setTitle("Enter a job to do:");           //CREATE DIALOG TITLE

    final EditText input = (EditText) new EditText(this);   //CREATE TEXT TO ADD BUILDER'S BODY
    dialogBuilder.setView(input);                                   //ADD TEXT VIEW INTO DIALOG'S BODY


    /*---DIALOG BUILDER ARACIYLA DIALOG'A OK VE CANCEL BUTONLARI EKLEME---*/
    dialogBuilder.setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            //OK BUTONA BASILDIĞINDA TODO'YA EKLE
            AddTask(input.getText().toString());
            input.setText("");

        }
    });

    dialogBuilder.setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            dialog.dismiss();
        }
    });
    /*---DIALOG BUILDER ARACIYLA DIALOG'A OK VE CANCEL BUTONLARI EKLEME---*/

    dialog = dialogBuilder.create();        //DIALOG'U YARAT

    todoList = new ArrayList<>();
    todoAdapter = new ArrayAdapter<String>(this, R.layout.simplerow,todoList);

    completedList = new ArrayList<>();
    completedAdapter = new ArrayAdapter<String>(this,R.layout.simplerow,completedList)/*{
        @Override
        public View getView(int position, View convertView, ViewGroup parent) {

            View view = super.getView(position, convertView, parent);
            TextView text = (TextView) view.findViewById(android.R.id.text1);


            text.setTextColor(Color.RED);


            return view;
        }
    }*/;




    NavigationView navigationView = findViewById(R.id.nav_view);        //FIND NAVIGATION VIEW'S ID

    navigationView.setNavigationItemSelectedListener(
            new NavigationView.OnNavigationItemSelectedListener() {
                @Override
                public boolean onNavigationItemSelected(MenuItem menuItem) {

                    if(menuItem.getTitle().toString().startsWith("Add")){
                        //AddTask();
                        dialog.show();
                    }
                    else if (menuItem.getTitle().toString().startsWith("To")){
                        ShowToDoTasks();
                    }
                    else if (menuItem.getTitle().toString().startsWith("Completed")){
                        ShowCompletedTasks();
                    }
                    else if (menuItem.getTitle().toString().startsWith("All")){
                        ShowAllTasks();
                    }
                    else if (menuItem.getTitle().toString().startsWith("Close")){
                        CloseProgram();
                    }
                    else
                        return false;
                    return true;
                }
            }
    );

}

public void ItemClicked(View v){

    txt = (TextView) v;

    if(!isCompletedJob) {
        CreateConfirmDialog();
    }
}

public void AddTask(String msg){

    Toast.makeText(this,msg,Toast.LENGTH_LONG).show();
    todoAdapter.add(msg);
    listView.setAdapter(todoAdapter);
    isCompletedJob=false;

}

public void ShowCompletedTasks(){
    //Toast.makeText(this,"Completed pressed",Toast.LENGTH_LONG).show();
    Toast.makeText(this,completedList.size()+"",Toast.LENGTH_LONG).show();
    listView.setAdapter(completedAdapter);
    isCompletedJob=true;
}

public void ShowAllTasks(){
    Toast.makeText(this,"Show All pressed",Toast.LENGTH_LONG).show();

    listView.setAdapter(allAdapter);

}

public void ShowToDoTasks(){
    Toast.makeText(this,"Show ToDo pressed",Toast.LENGTH_LONG).show();
    listView.setAdapter(todoAdapter);
    isCompletedJob=false;
}

public void CloseProgram(){
    Toast.makeText(this,"Close pressed",Toast.LENGTH_LONG).show();
}

public void UpdateLists(){

    txt.setTextColor(Color.RED);
    completedAdapter.add(txt.getText().toString());
    todoAdapter.remove(txt.getText().toString());

    Toast.makeText(MainActivity.this, txt.getText().toString() + " : Done",Toast.LENGTH_LONG).show();

}

public void CreateConfirmDialog(){
    /*--- CONFIRMATION IF THE CLICKED JOB COMPLETED OR NOT ---*/
    confirmBuilder = new AlertDialog.Builder(this);
    confirmBuilder.setTitle("Task Completed? ");

    confirmBuilder.setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            UpdateLists();
        }
    });

    confirmBuilder.setNegativeButton(android.R.string.no, new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            dialog.dismiss();
        }
    });

    confirmDialog = confirmBuilder.create();
    confirmDialog.show();
}
}

例外：

E / Android运行时：致命异常：主要流程：com.example.user.todoapp，PID：4825 java.lang.NullPointerException：尝试在空对象引用上调用虚拟方法“ void android.widget.TextView.setTextColor（int）” 在com.example.user.todoapp.MainActivity $ 3.getView（MainActivity.java:83）在android.widget.AbsListView.obtainView（AbsListView.java:2366）在android.widget.ListView.makeAndAddView（ListView.java:2052）在android.widget.ListView.fillDown（ListView.java:786）在android.widget.ListView.fillFromTop（ListView.java:847）在android.widget.ListView.layoutChildren（ListView.java:1826）在android.widget.AbsListView.onLayout（AbsListView.java:2165）在android.view.View.layout（View.java:20672）在android.view.ViewGroup.layout（ViewGroup.java:6194）在android.widget.LinearLayout.setChildFrame（LinearLayout.java:1812）在android.widget.LinearLayout.layoutVertical（LinearLayout.java:1656）在android.widget.LinearLayout.onLayout（LinearLayout.java:1565）在android.view.View.layout（View.java:20672）在android.view.ViewGroup.layout（ViewGroup.java:6194）在android.support.v4.widget.DrawerLayout.onLayout（DrawerLayout.java:1231）在android.view.View.layout（View.java:20672）在android.view.ViewGroup.layout（ViewGroup.java:6194）在android.widget.FrameLayout.layoutChildren（FrameLayout.java:323）在android.widget.FrameLayout.onLayout（FrameLayout.java:261）在android.view.View.layout（View.java:20672）在android.view.ViewGroup.layout（ViewGroup.java:6194）在android.support.v7.widget.ActionBarOverlayLayout.onLayout（ActionBarOverlayLayout.java:444）在android.view.View.layout（View.java:20672）在android.view.ViewGroup.layout（ViewGroup.java:6194）在android.widget.FrameLayout.layoutChildren（FrameLayout.java:323）在android.widget.FrameLayout.onLayout（FrameLayout.java:261）在android.view.View.layout（View.java:20672）在android.view.ViewGroup.layout（ViewGroup.java:6194）在android.widget.LinearLayout.setChildFrame（LinearLayout.java:1812）在android.widget.LinearLayout.layoutVertical（LinearLayout.java:1656）在android.widget.LinearLayout.onLayout（LinearLayout.java:1565）在android.view.View.layout（View.java:20672）在android.view.ViewGroup.layout（ViewGroup.java:6194）在android.widget.FrameLayout.layoutChildren（FrameLayout.java:323）在android.widget.FrameLayout.onLayout（FrameLayout.java:261）在com.android.internal.policy.DecorView.onLayout（DecorView.java:753）在android.view.View.layout（View.java:20672）在android.view.ViewGroup.layout（ViewGroup.java:6194）在android.view.ViewRootImpl.performLayout（ViewRootImpl.java:2792）在android.view.ViewRootImpl.performTraversals（ViewRootImpl.java:2319）在android.view.ViewRootImpl.doTraversal（ViewRootImpl.java:1460）在android.view.ViewRootImpl $ TraversalRunnable.run（ViewRootImpl.java:7183）在android.view.Choreographer $ CallbackRecord.run（Choreographer.java:949）在android.view.Choreographer.doCallbacks（Choreographer.java:761）在android.view.Choreographer.doFrame（Choreographer.java:696）在android.view.Choreographer $ FrameDisplayEventReceiver.run（Choreographer.java:935）在android.os.Handler.handleCallback（Handler.java:873）在android.os.Handler.dispatchMessage（Handler.java:99）在android.os.Looper.loop（Looper.java:193）在android.app.ActivityThread.main（ActivityThread.java:6669）在java.lang.reflect.Method.invoke（本机方法）在com.android.internal.os.RuntimeInit $ MethodAndArgsCaller.run（RuntimeInit.java:493）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:858）

如何更改并达到ListView项目的文本颜色？

0 个答案: