将值设置为textview时，应用崩溃

Question

I have made a simple activity with a textview, edittext and button. and I am trying to display value of edittext in textview when button is presses.

public void click() {
    EditText text1 = (EditText) findViewById(R.id.Text1);
    TextView text2 = (TextView) findViewById(R.id.Text2);    
        text2.setText("text");
        };
}

XML

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <EditText
        android:id="@+id/Text1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

        <requestFocus />
    </EditText>

    <TextView
        android:id="@+id/Text2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="TextView" />

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button"
        android:onClick="click" />

</LinearLayout>

when I press button app crashes.

Answer 1

Since you are using android:onClick="click" , android is expecting to find at runtime a method with the following signature: public void click(View view) .

change

public void click() {

with

public void click(View view) {

where view is the view's object you clicked on

Answer 2

You are using wrong signature. You need to add param

View view

So, calling of method should look like

public void click(View view) {//your code here }

Also call method click(View view) in MyActivity class.

Answer 3

Look at Android View : http://developer.android.com/reference/android/view/View.html

You need to pass a View in the method to update or play with it. Without which the application will crash.