5号总结

<?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_width="match_parent"
        android:layout_height="50dp"
        android:layout_weight="1"
        android:background="@android:color/background_dark"  />

    <TextView
        android:id="@+id/tv_show"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:padding="10dp"
        android:text="图片信息" />


    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:orientation="horizontal">

        <Button
            android:id="@+id/btn_previous"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="上一张" />


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


    </LinearLayout>
</LinearLayout>

package com.example.layout02;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
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 int[] images;
    private String[] title;


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

    private void initData() {
        title = new String[]{"第1张图片","第2张图片","第3张图片","第4张图片","第5张图片"  };
        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;
        index = 0;
    }

    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){
      switch (view.getId()){
          case R.id.btn_previous:
              if(index==0) {
                  index = num - 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]);
    }
}