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