我想在数组中找到最大值。我在Apples文档中找到了.max（）方法。
let heights = [67.5, 65.7, 64.3, 61.1, 58.5, 60.3, 64.9]
let greatestHeight = heights.max()
print(greatestHeight)
// Prints "Optional(67.5)"
我的数组具有自定义数据类型。数据类型包含两个来自整数类型的变量。如何从其中一个变量中找到最大值？
这是我的课程。
class Example: Codable {
// Variables
var value1: Int
var value2: Int
// Init
init(_value1: Int, _value2: Int) {
value1 = _value1
value2 = _value2
}
}
答案 0 :(得分：2)
好吧，class UsersController < ApiController
def show
@user = User.find(params[:id])
render json: @user, root: 'User', include: ['*', 'subscription', 'user_courses']
end
def index
@users = User.all
render json: @users, root: 'Users', include: ['*' ,'user_courses', 'courses']
end
def update
@user = User.find(params[:id])
uc = UserCourse.where(user_id: params[:id], course_id: params[:course_id]).first
uc.update_attributes(completed_quizzes: params[:completed_quizzes]) if params[:completed_quizzes]
uc.update_attributes(completed_lessons: params[:completed_lessons]) if params[:completed_lessons]
uc.update_attributes(completed: params[:completed]) if params[:completed]
end
end实例不是Class，因此您无法访问Array Array，但是可以在其中使用自定义functions获得更大的价值。
类似的东西是一种选择。
func更新：正如OP所指出的，他只需要比较第一个值。 编辑@Ashley答案，这可以解决
因为class Example: Codable {
// Variables
var value1: Int
var value2: Int
// Init
init(_value1: Int, _value2: Int) {
value1 = _value1
value2 = _value2
}
func max() -> Int {
if value1 > value2 {
return value1
}
return value2
}
}
// USAGE
var example = Example(_value1: 10, _value2: 20)
example.max()
将返回.max()，其中包含最高的object。
Value1答案 1 :(得分：2)
您可以通过遵循@OnLongClick(R.id.capture)
public boolean captureLongPressed() {
startRecord();
mMediaRecorder.start();
return true;
}
@OnTouch(R.id.capture)
public boolean captureOnTouch(MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_UP) {
if (isRecordButtonLongPressed) {
mIsRecording = false;
try {
mMediaRecorder.stop();
mMediaRecorder.reset();
} catch (RuntimeException ex) {
}
if (listener != null)
listener.onVideoRecorded(mVideoFileName);
return true;
}
}
return false;
}
private void startRecord() {
try {
setupMediaRecorder();
SurfaceTexture surfaceTexture = mTextureView.getSurfaceTexture();
surfaceTexture.setDefaultBufferSize(mPreviewSize.getWidth(), mPreviewSize.getHeight());
Surface previewSurface = new Surface(surfaceTexture);
Surface recordSurface = mMediaRecorder.getSurface();
mCaptureRequestBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_RECORD);
mCaptureRequestBuilder.addTarget(previewSurface);
mCaptureRequestBuilder.addTarget(recordSurface);
mCameraDevice.createCaptureSession(Arrays.asList(previewSurface, recordSurface), new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(@NonNull CameraCaptureSession session) {
try {
session.setRepeatingRequest(mCaptureRequestBuilder.build(), null, null);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
public void onConfigureFailed(@NonNull CameraCaptureSession session) {
}
}, null);
} catch (Exception e) {
e.printStackTrace();
}
}
private void setupMediaRecorder() throws IOException {
mMediaRecorder.setVideoSource(MediaRecorder.VideoSource.SURFACE);
mMediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
mMediaRecorder.setOutputFile(mVideoFileName);
mMediaRecorder.setVideoEncodingBitRate(1000000);
mMediaRecorder.setVideoFrameRate(30);
mMediaRecorder.setVideoSize(mVideoSize.getWidth(), mVideoSize.getHeight());
mMediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.H264);
mMediaRecorder.setOrientationHint(mTotalRotation);
mMediaRecorder.prepare();
}
@Override
public void onPause() {
closeCamera();
stopBackgroundThread();
super.onPause();
}
private void closeCamera() {
if (null != mCameraDevice) {
mCameraDevice.close();
mCameraDevice = null;
}
}
协议并实现Comparable（在这种情况下，我将2个值的总和进行比较）来实现此目的
func <答案 2 :(得分：1)
正如您在评论中澄清的那样：
我想找出该数组中所有对象的value1的最大值
可以通过将每个对象映射到其value1然后确定
最大值：
let maxValue1 = examples.map { $0.value1 }.max()
如果给定的数组真的很大，那么对 使用“惰性变体”来避免创建中间数组：
let maxValue1 = examples.lazy.map { $0.value1 }.max()