如何以编程方式在RelativeLayout中布置视图？

Question

I'm trying to achieve the following programmatically (rather than declaratively via XML):

<RelativeLayout...>
   <TextView ...
      android:id="@+id/label1" />
   <TextView ...
      android:id="@+id/label2"
      android:layout_below: "@id/label1" />
</RelativeLayout>

In other words, how do I make the second TextView appear below the first one, but I want to do it in code:

RelativeLayout layout = new RelativeLayout(this);
TextView label1 = new TextView(this);
TextView label2 = new TextView(this);
...
layout.addView(label1);
layout.addView(label2);
setContentView(layout);

Update:

Thanks, TreeUK. I understand the general direction, but it still doesn't work - "B" overlaps "A". What am I doing wrong?

RelativeLayout layout = new RelativeLayout(this);
TextView tv1 = new TextView(this);
tv1.setText("A");

TextView tv2 = new TextView(this);
tv2.setText("B");
RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(
        RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.FILL_PARENT);
lp.addRule(RelativeLayout.RIGHT_OF, tv1.getId());

layout.addView(tv1);        
layout.addView(tv2, lp);

Answer 1

From what I've been able to piece together, you have to add the view using LayoutParams.

LinearLayout linearLayout = new LinearLayout(this);

RelativeLayout.LayoutParams relativeParams = new RelativeLayout.LayoutParams(
        LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
relativeParams.addRule(RelativeLayout.ALIGN_PARENT_TOP);

parentView.addView(linearLayout, relativeParams);

All credit to sechastain, to relatively position your items programmatically you have to assign ids to them.

TextView tv1 = new TextView(this);
tv1.setId(1);
TextView tv2 = new TextView(this);
tv2.setId(2);

Then addRule(RelativeLayout.RIGHT_OF, tv1.getId());

Answer 2

Cut the long story short: With relative layout you position elements inside the layout.

1. create a new RelativeLayout.LayoutParams

    RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(...) 

   (whatever... fill parent or wrap content, absolute numbers if you must, or reference to an XML resource)

2. Add rules: Rules refer to the parent or to other "brothers" in the hierarchy.

    lp.addRule(RelativeLayout.BELOW, someOtherView.getId()) lp.addRule(RelativeLayout.ALIGN_PARENT_LEFT) 

3. Just apply the layout params: The most 'healthy' way to do that is:

    parentLayout.addView(myView, lp) 

Watch out : Don't change layout from the layout callbacks. It is tempting to do so because this is when views get their actual sizes. However, in that case, unexpected results are expected.

Answer 3

Just spent 4 hours with this problem. Finally realized that you must not use zero as view id . You would think that it is allowed as NO_ID == -1, but things tend to go haywire if you give it to your view...

Answer 4

Android 22 minimal runnable example

Source:

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.RelativeLayout;
import android.widget.TextView;

public class Main extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        final RelativeLayout relativeLayout = new RelativeLayout(this);

        final TextView tv1;
        tv1 = new TextView(this);
        tv1.setText("tv1");
        // Setting an ID is mandatory.
        tv1.setId(View.generateViewId());
        relativeLayout.addView(tv1);

        // tv2.
        final TextView tv2;
        tv2 = new TextView(this);
        tv2.setText("tv2");
        RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(
                ViewGroup.LayoutParams.WRAP_CONTENT,
                ViewGroup.LayoutParams.FILL_PARENT);
        lp.addRule(RelativeLayout.BELOW, tv1.getId());
        relativeLayout.addView(tv2, lp);

        // tv3.
        final TextView tv3;
        tv3 = new TextView(this);
        tv3.setText("tv3");
        RelativeLayout.LayoutParams lp2 = new RelativeLayout.LayoutParams(
            ViewGroup.LayoutParams.WRAP_CONTENT,
            ViewGroup.LayoutParams.WRAP_CONTENT
        );
        lp2.addRule(RelativeLayout.BELOW, tv2.getId());
        relativeLayout.addView(tv3, lp2);

        this.setContentView(relativeLayout);
    }
}

Works with the default project generated by android create project ... . GitHub repository with minimal build code .

Answer 5

call

tv1.setId(1) 

after

tv1.setText("A");

Answer 6

Try:

EditText edt = (EditText) findViewById(R.id.YourEditText);
RelativeLayout.LayoutParams lp =
    new RelativeLayout.LayoutParams
    (
        LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT
    );
lp.setMargins(25, 0, 0, 0); // move 25 px to right (increase left margin)
edt.setLayoutParams(lp); // lp.setMargins(left, top, right, bottom);

Answer 7

This approach with ViewGroup.MarginLayoutParams worked for me:

RelativeLayout myLayout = (RelativeLayout) findViewById(R.id.my_layout);

TextView someTextView = ...

int leftMargin = Util.getXPos();
int topMargin = Util.getYPos();

RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(
    new ViewGroup.MarginLayoutParams(
        RelativeLayout.LayoutParams.WRAP_CONTENT,
        RelativeLayout.LayoutParams.WRAP_CONTENT));

lp.setMargins(leftMargin, topMargin, 0, 0);

myLayout.addView(someTextView, lp);

Answer 8

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //setContentView(R.layout.activity_main);

        final RelativeLayout relativeLayout = new RelativeLayout(this);
        final TextView tv1 = new TextView(this);
        tv1.setText("tv1 is here");
        // Setting an ID is mandatory.
        tv1.setId(View.generateViewId());
        relativeLayout.addView(tv1);


        final TextView tv2 = new TextView(this);
        tv2.setText("tv2 is here");

        // We are defining layout params for tv2 which will be added to its  parent relativelayout.
        // The type of the LayoutParams depends on the parent type.
        RelativeLayout.LayoutParams tv2LayoutParams = new  RelativeLayout.LayoutParams(
            RelativeLayout.LayoutParams.WRAP_CONTENT,
            RelativeLayout.LayoutParams.WRAP_CONTENT);

        //Also, we want tv2 to appear below tv1, so we are adding rule to tv2LayoutParams.
        tv2LayoutParams.addRule(RelativeLayout.BELOW, tv1.getId());

        //Now, adding the child view tv2 to relativelayout, and setting tv2LayoutParams to be set on view tv2.
        relativeLayout.addView(tv2);
        tv2.setLayoutParams(tv2LayoutParams);
        //Or we can combined the above two steps in one line of code
        //relativeLayout.addView(tv2, tv2LayoutParams);

        this.setContentView(relativeLayout);
    }

}

Answer 9

If you really want to layout manually, i'd suggest not to use a standard layout at all. Do it all on your own, here a kotlin example:

class ProgrammaticalLayout @JvmOverloads constructor(context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0) : ViewGroup(context, attrs, defStyleAttr) { 
    private val firstTextView = TextView(context).apply {
        test = "First Text"
    }

    private val secondTextView = TextView(context).apply {
        text = "Second Text"
    }

    init {
        addView(firstTextView)
        addView(secondTextView)
    }

    override fun onLayout(changed: Boolean, left: Int, top: Int, right: Int, bottom: Int) {
        // center the views verticaly and horizontaly
        val firstTextLeft = (measuredWidth - firstTextView.measuredWidth) / 2
        val firstTextTop = (measuredHeight - (firstTextView.measuredHeight + secondTextView.measuredHeight)) / 2
        firstTextView.layout(firstTextLeft,firstTextTop, firstTextLeft + firstTextView.measuredWidth,firstTextTop + firstTextView.measuredHeight)

        val secondTextLeft = (measuredWidth - secondTextView.measuredWidth) / 2
        val secondTextTop = firstTextView.bottom
        secondTextView.layout(secondTextLeft,secondTextTop, secondTextLeft + secondTextView.measuredWidth,secondTextTop + secondTextView.measuredHeight)
    }

    override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) { 
        // just assume we`re getting measured exactly by the parent
        val measuredWidth = MeasureSpec.getSize(widthMeasureSpec)
        val measuredHeight = MeasureSpec.getSize(heightMeasureSpec)

        firstTextView.measures(MeasureSpec.makeMeasureSpec(meeasuredWidth, MeasureSpec.AT_MOST), MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED))
        secondTextView.measures(MeasureSpec.makeMeasureSpec(meeasuredWidth, MeasureSpec.AT_MOST), MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED))

        setMeasuredDimension(measuredWidth, measuredHeight)
    }
}

This might give you an idea how this could work