Textview Gravity not working properly in android

问题

What's wrong with my code, I'm trying to display my TextView named "invalid", in different locations (left,right,center), but the gravity (left,right,center) won't work!

My text.xml is

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="20dp" >

    <EditText 
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:id="@+id/etext"
        android:hint="@string/comment"
        android:inputType="textPassword"/>

    <LinearLayout 
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:weightSum="100">
        <Button
            android:id="@+id/button1"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="@string/button" 
            android:layout_weight="25"/>

        <ToggleButton
            android:id="@+id/toggleButton1"
            android:layout_width="fill_parent"
            android:layout_height="40dp"
            android:text="ToggleButton" 
            android:layout_weight="75"
            android:checked="true"
            android:paddingLeft="15dp"/>
    </LinearLayout>

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/invalid"
        android:layout_gravity="center"
        android:gravity="center" />
</LinearLayout>

My TextPlay.java is

public class TextPlay extends Activity {
    Button button;
    ToggleButton tbutton;
    TextView tview;
    EditText et;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.text);
        button = (Button) findViewById(R.id.button1);
        tbutton = (ToggleButton) findViewById(R.id.toggleButton1);
        tview = (TextView) findViewById(R.id.textView1);
        et = (EditText) findViewById(R.id.etext);
        tbutton.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                if (tbutton.isChecked()) {
                    et.setInputType(InputType.TYPE_CLASS_TEXT | InputType.TYPE_TEXT_VARIATION_PASSWORD);
                } else {
                    et.setInputType(InputType.TYPE_TEXT_VARIATION_PASSWORD);
                }
            }
        });
        button.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                String input = et.getText().toString();
                System.out.println(input);
                if (input.contentEquals("left")) {
                    tview.setGravity(Gravity.LEFT);
                } else if (input.contentEquals("right")) {
                    System.out.println("inside right");
                    tview.setGravity(Gravity.RIGHT);
                } else if (input.contentEquals("right")) {
                    tview.setGravity(Gravity.CENTER);
                }
            }
        });
    }
}

回答1:

You set this text view a width of "wrap_content" it means, what ever the text is, the view take the size of the text.

and in the LinearLayout , the default gravity (used here) is 'center'

you should try this :

<TextView
android:id="@+id/textView1"
android:layout_width="match_parent"   <= change this
android:layout_height="wrap_content"
android:text="@string/invalid"
android:gravity="center"   <= then this gravity will be taken into account
/>

回答2:

99% of the time, not working properly == not used properly.

You are mistaking gravity and layout_gravity.

gravity is the way the text will align itself in the TextView. The TextView being in wrap_content this does nothing, as the TextView is exactly the size of the text.

layout_gravity is the way the TextView will align itself in its parent, in your case in the vertical LinearLayout

回答3:

You have given your TextView width wrap_content, and that is the problem, Check below code and replace it to your code.

<TextView
android:id="@+id/txtInvalid"
android:layout_width="match_parent"   
android:layout_height="wrap_content"
android:text="@string/invalid"
android:gravity="center"   
/>

回答4:

set android:layout_width="fill_parent" for textView1

回答5:

Make sure you don't have something like that hanging around

app:layout_box="left|top"

来源：https://stackoverflow.com/questions/19025301/textview-gravity-not-working-properly-in-android