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Id cannot be resolved android

Android studio still doesn't recognize my text view and buttons despite all the changes I've made to other questions I've seen. Please, help

public void onButtonClick(View v)
{
    int a,c;
    EditText e1 = (EditText)findViewById(android.R.id.num);

    TextView t1= (TextView)findViewById(android.R.id.num1);
    a=Integer.parseInt(e1.getText().toString());


    c= a*a;
    t1.setText(Integer.toString(c));



}

XML file.

<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"
>

<TextView android:text="@string/hello_world" android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/textView" />

<EditText
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:inputType="number"
    android:ems="10"
    android:id="@+id/num"
    android:layout_below="@+id/textView"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_marginTop="73dp"
    android:text="Enter Text" />

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="click me"
    android:id="@+id/but"
    android:layout_below="@+id/num"
    android:layout_toRightOf="@+id/textView"
    android:layout_toEndOf="@+id/textView"
    android:layout_marginTop="44dp" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="New Text"
    android:id="@+id/textView2"
    android:layout_alignParentBottom="true"
    android:layout_alignRight="@+id/but"
    android:layout_alignEnd="@+id/but"
    android:layout_marginBottom="50dp" />


 </RelativeLayout>

Please help me, I'm a newbie so I don't understand what's going on with the errors. I've done the same thing before and it worked.

+3


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3 answers


Try the following:



  public void onButtonClick(View v)
{
int a,c;
EditText e1 = (EditText)findViewById(R.id.num);

TextView t1= (TextView)findViewById(R.id.num1);
a=Integer.parseInt(e1.getText().toString());


c= a*a;
t1.setText(Integer.toString(c));



}
0


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id

used to uniquely identify components.

So, for the first time we use @+id/name

. And after that we just use@id/name



So, change your layout to this:

    <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"
     >

    <TextView android:text="@string/hello_world"    
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/textView" />

   <EditText
   android:layout_height="wrap_content"
   android:inputType="number"
   android:ems="10"
   android:id="@+id/num"
   android:layout_below="@id/textView" //changed (removed + sign)
   android:layout_alignParentLeft="true"
   android:layout_alignParentStart="true"
   android:layout_marginTop="73dp"
   android:text="Enter Text" />

   <Button
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:text="click me"
   android:id="@+id/but"
   android:layout_below="@id/num" //changed (removed + sign)
   android:layout_toRightOf="@id/textView" //changed (removed + sign)
   android:layout_toEndOf="@id/textView" //changed (removed + sign)
   android:layout_marginTop="44dp" />

  <TextView
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:text="New Text"
   android:id="@+id/textView2"
   android:layout_alignParentBottom="true"
   android:layout_alignRight="@id/but" //changed (removed + sign)
   android:layout_alignEnd="@id/but" //changed (removed + sign)
   android:layout_marginBottom="50dp" />



   </RelativeLayout>
+1


source


try this it could be like

private Button add;
@Override
    protected void onCreate(Bundle savedInstanceState)
 {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

       add= (Button) findViewById(R.id.button1);
        add.setOnClickListener(this);

}
@Override
    public void onClick(View v)
    {

    switch (v.getId()) {

case R.id.But:   // this is your xml id for button

     //Your code 

        break;
}
}
0


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