一 : 准备图片

①,将2张图片放入 res -> drawable 中,如下所示:

②, 在UI中加入ImageView组建,方法将ImageView拖入到设计窗,弹出选择图片框(UI) ②-1 , 拖ImageView到UI设计窗 ②-2 ,在弹出的“Resources”框中中,选择需要显示的图片,如下

二 :写代码,当点击btn后,换一张图片

①,这个ImageView的Id为 img_tree ②,代码

package com.kayer.myfirstdemo;

import android.app.Activity;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;

public class MainActivity extends Activity {
    private TextView txt_t = null;
    private Button btn_ok = null;
    private ImageView img_tree = null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        this.txt_t = (TextView)this.findViewById(R.id.txt_t);
        this.btn_ok = (Button)this.findViewById(R.id.btn_ok);
        this.img_tree = (ImageView)this.findViewById(R.id.img_tree);
        this.btn_ok.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                CharSequence a = MainActivity.this.txt_t.getText();
                if( a.toString() == "Hello World!" ){
                    MainActivity.this.txt_t.setText( "Aonaufly" );
                }else{
                    MainActivity.this.txt_t.setText( "Hello World!" );
                }
                Drawable icon_1 = getDrawable( R.drawable.tree123 );
                MainActivity.this.img_tree.setImageDrawable( icon_1 );
            }
        });
    }
}

三:安装到真机中测试


①,初始状态


②,点击按钮后