2.13日自学成果

package com.example.xiangce;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private ImageView mImage;
    private TextView mText;
    private int num;
    private int index;
    private String[] title;
    private int[] images;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //初始化
        initView();
        //初始化构建
        initData();
    }

    private void initData() {
        title = new String[]{"第1张","第2张","第3张","第4张","第5张"};
        images = new int[]{R.drawable.a,R.drawable.b,R.drawable.c,R.drawable.d,R.drawable.e};
        mImage.setImageResource(images[0]);
        mText.setText(title[0]);
        num = title.length;//图片张数
        index = 0;//当前图片页数
    }

    private void initView() {
        mImage = findViewById(R.id.iv_show);
        mText = findViewById(R.id.tv_show);
        findViewById(R.id.btn_previous).setOnClickListener(this);
        findViewById(R.id.btn_next).setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
     //切换张数
        switch(view.getId()){
            case R.id.btn_previous:
                if(index==0)
                {
                    index=title.length-1;
                }
                else{
                index--;}
                break;
            case R.id.btn_next:
                if(index==4){
                    index=0;
                }else{
                    index++;
                }
                break;
        }
        updateImageAndTitle();
    }

    private void updateImageAndTitle() {

        mImage.setImageResource(images[index]);
        mText.setText(title[index]);
    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical"
    tools:context=".MainActivity">

   <ImageView
       android:id="@+id/iv_show"
       android:layout_weight="1"
       android:background="@android:color/background_dark"
       android:layout_width="match_parent"
       android:layout_height="50dp"
       />
    <TextView
        android:id="@+id/tv_show"
        android:text="图片信息"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:padding="10dp"
/>
    <LinearLayout
        android:gravity="center"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
    <Button
        android:id="@+id/btn_previous"
        android:text="上一张"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

    <Button
        android:id="@+id/btn_next"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="下一张" />
</LinearLayo>
效果图