2.6 UI控件与后台联系实现

完成的结果如下 :

当点击 左按钮时 最上边的显示栏更改为左 反之则为右  点击开关显示为开或者关

下边两个为显示加载的界面 在输入栏输入数值可以控制进度条的百分比并且显示在最上边 点击图片一二切换图片

勾选下边三个选项可以在最上方显示栏中显示出来 勾选的课程 可多选

选择评价等级会出现选择的等级。

源代码如下：

 package com.example.uidemo;

 import androidx.appcompat.app.AppCompatActivity;

 import android.os.Bundle;
 import android.text.TextUtils;
 import android.view.View;
 import android.widget.Button;
 import android.widget.CheckBox;
 import android.widget.CompoundButton;
 import android.widget.EditText;
 import android.widget.ImageView;
 import android.widget.ProgressBar;
 import android.widget.RadioGroup;
 import android.widget.RatingBar;
 import android.widget.SeekBar;
 import android.widget.Switch;
 import android.widget.TextView;
 import android.widget.Toast;

 public class MainActivity extends AppCompatActivity {
     TextView  display;
     Button buttonleft,buttonright,button3;
     Switch aSwitch;
     ProgressBar progressBar;
     EditText editText;
     RadioGroup radioGroup;
     ImageView imageView;
     SeekBar seekBar;
     CheckBox checkBoxyuwen,checkBoxshuxue,checkBoxyingyu;
     RatingBar ratingBar;
     String yuwen="";
     String shuxue="";
     String yingyu="";

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         display=findViewById(R.id.textView);
         buttonleft=findViewById(R.id.button);
         buttonright=findViewById(R.id.button2);
         button3=findViewById(R.id.button3);
         aSwitch=findViewById(R.id.switch1);
         progressBar=findViewById(R.id.progressBar3);
         editText=findViewById(R.id.editText);
         radioGroup=findViewById(R.id.radioGroup);
         imageView=findViewById(R.id.imageView);
         seekBar=findViewById(R.id.seekBar);
         checkBoxyuwen =findViewById(R.id.checkBox);
         checkBoxshuxue=findViewById(R.id.checkBox2);
         checkBoxyingyu=findViewById(R.id.checkBox3);
         ratingBar=findViewById(R.id.ratingBar);

         buttonleft.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View v) {
                 display.setText(R.string.button1);
             }
         });
         buttonright.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View v) {
                 display.setText(R.string.button2);
             }
         });

         aSwitch.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
             @Override
             public void onCheckedChanged(CompoundButton buttonView, boolean b) {
                 if(b) {
                     display.setText("开");
                 }
                 else{
                     display.setText("关");
                 }
             }
         });
         button3.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View v) {
                 String s=editText.getText().toString();
                 if(TextUtils.isEmpty(s)){
                     s="0";
                 }
                 progressBar.setProgress(Integer.valueOf(s));
                 display.setText(s);
             }
         });

         radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
             @Override
             public void onCheckedChanged(RadioGroup group, int i) {
                 if(i==R.id.radioButton){
                     imageView.setImageResource(R.drawable.ic_launcher_background);
                 } else {
                     imageView.setImageResource(R.drawable.ic_launcher_foreground);
                 }
             }
         });

         seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
             @Override
             public void onProgressChanged(SeekBar seekBar, int i, boolean fromUser) {
                 display.setText(String.valueOf(i));
             }

             @Override
             public void onStartTrackingTouch(SeekBar seekBar) {

             }

             @Override
             public void onStopTrackingTouch(SeekBar seekBar) {

             }
         });

         checkBoxyuwen.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
             @Override
             public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                 if(isChecked){
                     yuwen="语文";
                 }else {
                     yuwen="";
                 }
                 display.setText(yuwen+shuxue+yingyu );
             }
         });

         checkBoxshuxue.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
             @Override
             public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                 if(isChecked){
                     shuxue="数学";
                 }else{
                     shuxue="";
                 }
                 display.setText(yuwen+shuxue+yingyu );
             }
         });

         checkBoxyingyu.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
             @Override
             public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                 if(isChecked){
                     yingyu="英语";
                 }else{
                     yingyu="";
                 }
                 display.setText(yuwen+shuxue+yingyu );
             }
         });
         ratingBar.setOnRatingBarChangeListener(new RatingBar.OnRatingBarChangeListener() {
             @Override
             public void onRatingChanged(RatingBar ratingBar, float rating, boolean fromUser) {
                 Toast.makeText(getApplicationContext(),String.valueOf(rating)+"星的评价！",Toast.LENGTH_SHORT).show();
             }
         });
     }
 }

首先确定变量，然后与前台的控件相互关联，然后在代码的帮助下实现操作