设置视图的宽高

 AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"><applicationandroid:allowBackup="true"android:icon="@mipmap/ic_launcher"android:label="@string/app_name"android:roundIcon="@mipmap/ic_launcher_round"android:supportsRtl="true"android:theme="@style/Theme.MyApplication"><activityandroid:name=".ViewBorderActivity"android:exported="false" /><activityandroid:name=".TextSizeActivity"android:exported="true" /></application></manifest>

activity_view_border.xml

<?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"><TextViewandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_marginTop="5dp"android:background="#00ffff"android:text="视图宽高采用wrap_content定义"android:textColor="#000000"android:textSize="17sp" /><TextViewandroid:layout_width="match_parent"android:layout_height="wrap_content"android:layout_marginTop="5dp"android:background="#00ffff"android:text="视图宽高采用match_parent定义"android:textColor="#000000"android:textSize="17sp" /><TextViewandroid:layout_width="300dp"android:layout_height="wrap_content"android:layout_marginTop="5dp"android:background="#00ffff"android:text="视图宽度采用固定大小"android:textColor="#000000"android:textSize="17sp" /><TextViewandroid:id="@+id/tv_code"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_marginTop="5dp"android:background="#00ffff"android:text="通过代码指定视图宽度"android:textColor="#000000"android:textSize="17sp" /></LinearLayout>

ViewBorderActivity.java

package com.example.chapter03;import android.os.Bundle;
import android.view.ViewGroup;
import android.widget.TextView;import androidx.activity.EdgeToEdge;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.graphics.Insets;
import androidx.core.view.ViewCompat;
import androidx.core.view.WindowInsetsCompat;import com.example.chapter03.util.Utils;public class ViewBorderActivity extends AppCompatActivity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_view_border);TextView tv_code = findViewById(R.id.tv_code);//获取tv_code的布局参数（含宽度和高度）ViewGroup.LayoutParams params = tv_code.getLayoutParams();//修改布局参数中的宽度数值，注意默认px单位，需要吧dp数值转成px数值params.width = Utils.dip2px(this,300);//设置tv_code的布局参数tv_code.setLayoutParams(params);}
}

Utils.java

package com.example.chapter03.util;import android.content.Context;public class Utils {public static int dip2px(Context context, float dpValue){//获取当前手机的像素密度（1个dp对应几个px）float scale =context.getResources().getDisplayMetrics().density;return  (int)(dpValue*scale + 0.5f);}
}