对此有 FC 问题
private TextView msg, NameOut, DateOut;
msg = (TextView) findViewById(R.id.txtviewOut) ;
下线......(问题出在这里)
msg.setVisibility(View.INVISIBLE);//set visibility to false on create
如何在应用程序启动时将此 TextView (msg) 的可见性设置为 false？
更新后 #1 回答编辑
好的，这里是所有代码:
fragment_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context=".MainActivity$PlaceholderFragment">
<EditText
android:id="@+id/textenter"
android:layout_height="wrap_content"
android:layout_width="match_parent"
android:layout_below="@+id/lbledt1"
android:layout_alignParentLeft="true" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Enter Name"
android:id="@+id/lbledt1"
android:layout_marginTop="26dp"
android:layout_centerHorizontal="true" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Enter your date of birth (e.g. xx July 19xx)"
android:id="@+id/textView"
android:layout_below="@+id/textenter"
android:layout_centerHorizontal="true"
android:layout_marginTop="57dp" />
<EditText
android:id="@+id/editText"
android:layout_height="wrap_content"
android:layout_width="match_parent"
android:layout_below="@+id/textView"
android:layout_alignParentLeft="true" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Press this button"
android:id="@+id/button"
android:layout_centerVertical="true"
android:layout_centerHorizontal="true" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="You have been awesome since"
android:id="@+id/txtviewOut"
android:layout_marginTop="86dp"
android:textIsSelectable="false"
android:layout_below="@+id/button"
android:layout_centerHorizontal="true" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:id="@+id/txtoutName"
android:textIsSelectable="false"
android:layout_alignBottom="@+id/txtviewOut"
android:layout_centerHorizontal="true"
android:layout_marginBottom="41dp" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:id="@+id/txtOutDate"
android:layout_marginTop="28dp"
android:textIsSelectable="false"
android:layout_below="@+id/txtviewOut"
android:layout_centerHorizontal="true" />
MainActivity.java:
package com.example.helloandroidstudio;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.os.Build;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends ActionBarActivity {
private Button btnClick;
private EditText Name, Date;
private TextView msg, NameOut, DateOut;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
btnClick = (Button) findViewById(R.id.button) ;
Name = (EditText) findViewById(R.id.textenter) ;
Date = (EditText) findViewById(R.id.editText) ;
msg = (TextView) findViewById(R.id.txtviewOut) ;
NameOut = (TextView) findViewById(R.id.txtoutName) ;
DateOut = (TextView) findViewById(R.id.txtOutDate) ;
// msg.setVisibility(View.GONE);//set visibility to false on create
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment())
.commit();
}
}
public void onClick(View v)
{
if (v == btnClick)
{
if (Name.equals("") == false && Date.equals("") == false)
{
NameOut = Name;
DateOut = Date;
msg.setVisibility(View.VISIBLE);
}
else
{
msg.setText("Please complete both fields");
msg.setVisibility(View.VISIBLE);
}
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.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.
switch (item.getItemId()) {
case R.id.action_settings:
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
return rootView;
}
}
}
我用setInvisibility(View.GONE)尝试了，但是还是FC
我检查了 id 值，有一个辅助值分配，我确实做了对象的类型转换......
请记住，我已经完成了 c#，但这是我的第一个 java/android 应用程序，所以请耐心等待
最佳答案
好吧，我有点怀疑你到底想完成什么，但我会尝试澄清一些概念
msg.setVisibility(View.INVISIBLE); // for hiding but keeping the place of your view
msg.setVisibility(View.GONE);// for hiding it completely , view will not take any place