ImageView使用

李小白是一只喵

发布于 2020-04-24 08:44:40

7310

发布于 2020-04-24 08:44:40

文章被收录于专栏：算法微时光算法微时光

image.png

ImageView

ImageView是图片控件,可以使用其显示图片.

xml写法:

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        tools:srcCompat="@tools:sample/backgrounds/scenic[0]" />

加载图片入项目

为了引用图片,需要先加载图片.

进入到项目的生成目录里,找到对应的res目录下的drawable中:

image.png

如上图,讲两个图片放在此目录下.

这样我们就可以在项目中看到想要的图片了.

image.png

然后尝试加载图片:

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        tools:srcCompat="@drawable/001.jpg" />

但是编译报错了Error: The resource name must start with a letter

Caused by: com.android.build.gradle.tasks.ResourceException: /home/user/AndroidStudioProjects/image/app/src/main/res/drawable/001.jpg: Error: The resource name must start with a letter
    at com.android.build.gradle.tasks.MergeResources.doIncrementalTaskAction(MergeResources.java:424)
    at com.android.build.gradle.internal.tasks.IncrementalTask.taskAction(IncrementalTask.java:110)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.gradle.internal.reflect.JavaMethod.invoke(JavaMethod.java:73)
    at org.gradle.api.internal.project.taskfactory.IncrementalTaskAction.doExecute(IncrementalTaskAction.java:50)
    at org.gradle.api.internal.project.taskfactory.StandardTaskAction.execute(StandardTaskAction.java:39)
    at org.gradle.api.internal.project.taskfactory.StandardTaskAction.execute(StandardTaskAction.java:26)
    at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter$1.run(ExecuteActionsTaskExecuter.java:124)
    at org.gradle.internal.progress.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:336)
    at org.gradle.internal.progress.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:328)
    at org.gradle.internal.progress.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:199)
    at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:110)
    at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeAction(ExecuteActionsTaskExecuter.java:113)
    at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:95)
    ... 108 more

这是因为图片使用了数字作为名字开头.

这个是个坑.....

我们再来修改下图片的名字

image.png

将xml文件也做相应的修改

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        tools:srcCompat="@drawable/p001" />

再次编译,这时就可以了O(∩_∩)O

image.png

加载图片还是挺方便的.

下面尝试再添加个按钮,点击按钮后更换ImageView中的图片

小实验

首先添加个next按钮:

    <Button
        android:id="@+id/next"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="next" />

并在代码中获取到按钮:

next = (Button)findViewById(R.id.next);

再为按钮设定好点击监听事件:

       next.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v) {
                i++;

                if(i % 2 != 0)
                    image.setImageResource(R.drawable.p123);
                else
                    image.setImageResource(R.drawable.p001);
            }
        });

基本就差不多了.

全部代码

MainActivity.java文件:

package com.example.user.image;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;


public class MainActivity extends AppCompatActivity {

    Button next;
    ImageView image;

    int i = 0;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        next = (Button)findViewById(R.id.next);
        image = (ImageView) findViewById(R.id.imageView);

        image.setImageResource(R.drawable.p001);

        next.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v) {
                i++;

                if(i % 2 != 0)
                    image.setImageResource(R.drawable.p123);
                else
                    image.setImageResource(R.drawable.p001);
            }
        });
    }
}

activity_main.xml文件

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 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"
    tools:context=".MainActivity">


    <ImageView
        android:id="@+id/imageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        tools:srcCompat="@drawable/p001" />

    <Button
        android:id="@+id/next"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="next" />

</android.support.constraint.ConstraintLayout>

运行效果: