我的TextView没看到

Question

I want to see on the screen a Button object, a TextView object and a MyView object. But only appear Button object and MyVıew object. I think , MyView overlapping(above the TextView ) with TextView. Because If I don't add( b.addView(a); ) MyView object to my layout, Button and TextView objects appear on the screen. But If I add( b.addView(a); ) MyView , TextView is gone. How can I solve this problem?

MyView.java file:

package com.example.mehmet.catchtheball;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.View;

public class MyView extends View {

    public MyView(Context context) {
        super(context);
    }
    @Override
    protected void onDraw(Canvas canvas) {

        super.onDraw(canvas);
        Paint paint = new Paint();
        paint.setColor(Color.WHITE);
        canvas.drawPaint(paint);
        paint.setColor(Color.parseColor("lightGray"));
        canvas.drawCircle(500, 500, 150, paint);
    }
    public MyView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public MyView(Context context, AttributeSet attrs, int defStyle) {
       super(context, attrs, defStyle);
    }
}

Customer.java file :

package com.example.mehmet.catchtheball;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;


public class Customer extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_customer);

        MyView a = new MyView(this);
        RelativeLayout b = (RelativeLayout)findViewById(R.id.relativeLayout);
        b.addView(a); // If I do this , TextView gone.

        final TextView label = (TextView) findViewById(R.id.textView3);
        label.setText("HelloEveryOne"); // My TextView

        a.setOnTouchListener(new View.OnTouchListener() {
            public boolean onTouch(View view, MotionEvent motionEvent) {
               return true;
            }
        });
    }
}

activity_customer.xml file :

    <?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/relativeLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.mehmet.catchtheball.main">

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:onClick="undo"
        android:text="@string/undo" />


    <TextView
        android:id="@+id/textView3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBottom="@+id/button"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginLeft="27dp"
        android:layout_marginStart="27dp"
        tools:textColor="@android:color/background_dark" />

</RelativeLayout>

Answer 1

Try with this activity_customer.xml:

<?xml version="1.0" encoding="utf-8"?>
<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"
    tools:context="com.example.mehmet.catchtheball.main">

    <RelativeLayout
        android:id="@+id/relativeLayout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:onClick="undo"
        android:text="@string/undo" />


    <TextView
        android:id="@+id/textView3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBottom="@+id/button"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginLeft="27dp"
        android:layout_marginStart="27dp"
        tools:textColor="@android:color/background_dark" />

</RelativeLayout>

Answer 2

Add a LinearLayout as container below textView3 and add all to then

In the XML here you posted, add a with layout_belowOf=textView3, at your code where you do b.addView(a) replace with: LinearLayout c = findViewById(R.id.ll_c_container) and c.addView(a)

If you want to all components to be in an linear axis you can have just one linearlayout (all addViews will add below the last view)

Answer 3

    <RelativeLayout
        android:id="@+id/relativeLayout"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">

        <Button
            android:id="@+id/button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentTop="true"
            android:layout_centerHorizontal="true"
            android:onClick="undo"
            android:text="@string/undo" />


        <TextView
            android:id="@+id/textView3"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentStart="true"
            android:layout_below="@+id/button"
            android:layout_marginStart="27dp" />
    </RelativeLayout>

In your java class just do this one (Sorry i am writing kotlin code

MyView a = new MyView(this);
        val params = RelativeLayout.LayoutParams(
           ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT)
    params.addRule(RelativeLayout.BELOW, textView3.id)
    params.addRule(RelativeLayout.ALIGN_PARENT_START, RelativeLayout.TRUE)
    relativeLayout.addView(textView, params)