基本布局-----GridLayout(网格布局)

将整个容器划分为rows×columns个网格，每个网格可以放一个组件，也可以设置一个组件横跨多少列，纵跨多少行。
实例：计算器

<?xml version="1.0" encoding="utf-8"?>
<GridLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:rowCount="6"
    android:columnCount="4"
    tools:context=".MainActivity"
    android:id="@+id/root">
    <!--定义一个横跨四列的文本框，并设置颜色背景等属性-->
    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="0"
        android:layout_columnSpan="4"
        android:textSize="50sp"
        android:layout_marginLeft="2pt"
        android:layout_marginRight="2pt"
        android:padding="3pt"
        android:layout_gravity="right"
        android:background="#eee"
        android:textColor="#000"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
     <!--定义一个横跨四列的按钮-->
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_columnSpan="4"
        android:text="清除"/>
</GridLayout>

package com.example.gridlayoutactivity;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.Gravity;
import android.widget.Button;
import android.widget.GridLayout;

public class MainActivity extends AppCompatActivity {

    GridLayout gridLayout;
    //定义16个按钮的文本
    String [] chars=new String[]{
            "7","8","9","/",
            "4","5","6","*",
            "1","2","3","-",
            ".","0","=","+",
    };
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        gridLayout=findViewById(R.id.root);
        for(int i=0;i<chars.length;i++){
            //创建按钮
            Button bn=new Button(this);
            bn.setText(chars[i]);
            //设置按钮字号大小
            bn.setTextSize(40);
            //设置按钮四周的空白区域
            bn.setPadding(5,35,5,35);
            //指定该组件所在的行
            GridLayout.Spec rowSpec=GridLayout.spec(i/4+2);
            //指定改组件的列
            GridLayout.Spec colSpec=GridLayout.spec(i%4);
            GridLayout.LayoutParams params=new GridLayout.LayoutParams(rowSpec,colSpec);
            //指定该组件占满父容器
            params.setGravity(Gravity.FILL);
            gridLayout.addView(bn,params);
        }
    }
}