我昨天安装了Android Studio，我试着用LogCat查看日志。但是日志里什么都没有。我使用终端运行。/adb logcat，它工作。
有人能给我解释一下如何在Android Studio中使用logcat吗?
当前回答
我检查了答案，只是在检查我的日志时偶然发现我的错误。 确保右边的方框显示“只显示选定的应用程序”。我的显示的是“Firebase”，所以它显示了来自Firebase的消息。
其他回答
我刚把它修好了。在DDMS显示的最右边寻找恢复Devices Logcat视图和ADB视图的小图标。
When the DDMS first came up with both the "ADB Logs" and the "Devices | logcat" tab showing. The "Devices | logcat" is the one that should be showing the device output, but was blank. Somehow I managed to hide one or the other of those tabs, I forget exactly how. But, off to the right there was a tiny icon that said "Restore ADB" view, and I clicked it and it came up. Then there was another tiny icon that said "Restore Devices logcat view". I clicked that, and all of a sudden it appeared and was showing the device output again.
**
如果你仍然被logcat为空所困扰，请阅读这篇文章
**
经过几个月的烦恼和麻烦，我刚刚解决了这个问题。 没有任何帮助，设备监视器在调试期间工作良好，但标准的logcat视图总是空的。
原因简单得令人恼火: logcat视图在那里，但它已被移动到0宽度的更新!
你在“ALT 6”选项卡，你看到两个选项卡“ADB日志”和“设备| logcat” Devices | logcat实际上意味着它由Devices和logcat组成，用垂直边界分隔。 垂直边界可以移动，在更新期间，它似乎已经移动到100%正确。
这将导致logcat被收集但不显示，将鼠标指针移动到工具窗口的右侧，并将logcat拖回视图。
这个解决方案不会帮助每个人，但我发现许多人与工作ADB连接仍然没有logcat输出，这些可能会受到同样的问题。
这不是一个技术性的答案，但您可能想要检查logcat的搜索框。如果输入了任何字符，你的logcat将为空，因为它将搜索特定的字符或单词，然后如果它不存在，你的logcat日志将完全为空。
这偶尔发生在我使用模拟器。我只需插入一个设备并运行应用程序。Logcat就可以继续工作，当我回到模拟器时它也可以这样做。 我想只要切换两个设备和/或模拟器就可以了。
当其他方法都不管用的时候，我是这么做的。由于adb logcat工作得很好，我决定依赖它。在Android Studio的嵌入式终端中运行adb logcat -v color，输出与普通的logcat类似，并且允许代码链接工作:
但这也带来了一些问题:
您不能指定要监视的包。使用——pid=<your pid >选项，您可以查看单个进程的输出。但由于每次重新启动应用程序，PID都会发生变化，因此每次重新启动时都要重新运行此命令。 (在我看来)这些颜色令人讨厌。 输出字段没有与之前的消息对齐，整个事情没有很好地格式化，这使得跟踪logcat比它应该发生的要困难得多(尽管嵌入的logcat也发生了同样的情况)。
所以我决定制作自己的工具来自动监视我的包PID并美化logcat输出:
import java.awt.AWTException;
import java.io.*;
import java.util.ArrayList;
import java.awt.Robot;
import java.awt.event.KeyEvent;
public class Logcat {
private static final String ADB_FILE_PATH = "adb";
// Customizations,
private static final Color V_COLOR = Color.RESET;
private static final Color D_COLOR = Color.RESET;
private static final Color I_COLOR = Color.RESET;
private static final Color W_COLOR = Color.BLUE;
private static final Color E_COLOR = Color.RED_BRIGHT;
private static final Color HINT_COLOR = Color.MAGENTA_BOLD_BRIGHT;
private static final Color OTHER_COLOR = Color.GREEN_BOLD_BRIGHT;
private static final int DATE_LENGTH = 5;
private static final int TIME_LENGTH = 12;
private static final int PROCESS_ID_LENGTH = 5;
private static final int THREAD_ID_LENGTH = 5;
private static final int LOG_LEVEL_LENGTH = 1;
private static final int TAG_LENGTH = 20;
private static final int MESSAGE_LENGTH = 110;
private static final String SEPARATOR = " | ";
private static final String CONTINUATION = "→";
private static final String INDENTATION = " ";
private static final int PROCESS_IDS_UPDATE_INTERVAL_MILLIS = 1224;
private static final int HISTORY_LENGTH = 1000;
// State,
private static boolean skipProcessIDCheck;
private static ArrayList<String> processIDs = new ArrayList<String>();
private static String logLevelToShow="V"; // All.
private static Process logcatProcess;
private static boolean appClosed;
private static boolean stopEverything;
private static String[] history = new String[HISTORY_LENGTH];
private static int currentLocationInHistory, historyLength;
public static void main(final String args[]) {
clearAndroidStudioConsole();
System.out.println("besm Allah");
// Get processes ids of the provided package,
if (args.length==0) {
skipProcessIDCheck = true;
} else {
skipProcessIDCheck = false;
getProcessIDs (args[0]); // Do it once before we start.
monitorProcessIDs(args[0]); // Do it periodically from now on.
}
// Start capturing and prettifying logcat,
if (!monitorLogcat()) {
stopEverything = true;
return;
}
// Handle user input,
handleUserInput();
}
private static void watch(final Process process, final ProcessListener listener) {
// Read process standard output and send it to the listener line by line,
new Thread() {
public void run() {
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(process.getInputStream()));
String line = "";
try {
do {
if (bufferedReader.ready()) {
line = bufferedReader.readLine();
if (line!=null && !line.isEmpty()) listener.onNewLine(line);
} else {
Thread.sleep(100);
}
} while (line!=null && !stopEverything);
} catch (Exception e) { e.printStackTrace(); }
}
}.start();
}
private static void monitorProcessIDs(String packageName) {
// Continuously monitor the process IDs of this package and update when changed,
new Thread() {
public void run() {
do {
try { Thread.sleep(PROCESS_IDS_UPDATE_INTERVAL_MILLIS); } catch (InterruptedException e) {}
getProcessIDs(packageName);
} while (!stopEverything);
}
}.start();
}
private static void getProcessIDs(String packageName) {
// Get the process IDs associated with this package once,
ArrayList<String> newProcessIDs = new ArrayList<String>();
Runtime runtime = Runtime.getRuntime();
try {
Process getPIDProcess = runtime.exec(ADB_FILE_PATH + " shell ps");
watch(getPIDProcess, (line) -> {
if (line.contains(packageName)) {
newProcessIDs.add(removeRedundantSpaces(line).split(" ")[1]);
}
});
getPIDProcess.waitFor();
Thread.sleep(500); // Make sure we've already handled all the input from the process.
} catch (Exception e) { e.printStackTrace(); }
// Return immediately if program is closed,
if (stopEverything) return ;
// Some action upon getting the pid(s),
boolean shouldRepeatHistory = false;
if (newProcessIDs.isEmpty()) {
// Just closed,
if (!appClosed) {
appClosed = true;
prettify("----- App closed -----");
}
} else if (appClosed) {
// Just opened, clear,
appClosed = false;
clearAndroidStudioConsole();
prettify("----- App opened -----");
shouldRepeatHistory = true;
} else {
// Detect changes in processes,
for (String pid : newProcessIDs) {
if (!processIDs.contains(pid)) {
clearAndroidStudioConsole();
prettify("----- Process(es) changed (or app restarted - some logs could have been missed) -----");
shouldRepeatHistory = true;
break ;
}
}
}
// Set the new PID(s),
processIDs = newProcessIDs;
if (shouldRepeatHistory) repeatHistory();
}
private static boolean monitorLogcat() {
Runtime runtime = Runtime.getRuntime();
try {
logcatProcess = runtime.exec(ADB_FILE_PATH + " logcat -v threadtime");
watch(logcatProcess, (line) -> {
// Learn history, in case we need to repeat it,
if (appClosed || processLogcatLine(line)) {
history[currentLocationInHistory] = line;
currentLocationInHistory = (currentLocationInHistory + 1) % history.length;
if (historyLength<history.length) historyLength++;
}
});
} catch (Exception e) {
e.printStackTrace();
return false;
}
return true;
}
private static boolean processLogcatLine(String line) {
try {
return prettify(line);
} catch (Exception e) {
print(line, OTHER_COLOR);
System.out.println();
// Debug,
e.printStackTrace();
return true;
}
}
// Returns true if line should be kept in history,
private static synchronized boolean prettify(String line) {
if (line.startsWith("-")) {
// It's a "beginning of <something>" line,
print(line, HINT_COLOR);
System.out.println();
return true;
}
// Get the individual fields,
String date = line.substring(0, line.indexOf(' ')); line = line.substring(line.indexOf(' ')+1); line = line.trim();
String time = line.substring(0, line.indexOf(' ')); line = line.substring(line.indexOf(' ')+1); line = line.trim();
String processID = line.substring(0, line.indexOf(' ')); line = line.substring(line.indexOf(' ')+1); line = line.trim();
// Break early if possible,
if (!skipProcessIDCheck && !processIDs.contains(processID.trim())) return false;
// Continue parsing,
String threadID = line.substring(0, line.indexOf(' ')); line = line.substring(line.indexOf(' ')+1); line = line.trim();
String logLevel = line.substring(0, line.indexOf(' ')); line = line.substring(line.indexOf(' ')+1); line = line.trim();
// Break early if possible,
switch (logLevel) {
case "V": if (!"V" .contains(logLevelToShow)) return true; break;
case "D": if (!"VD" .contains(logLevelToShow)) return true; break;
case "I": if (!"VDI" .contains(logLevelToShow)) return true; break;
case "W": if (!"VDIW" .contains(logLevelToShow)) return true; break;
case "E": if (!"VDIWE".contains(logLevelToShow)) return true; break;
}
// Continue parsing,
String tag = line.substring(0, line.indexOf(':')); line = line.substring(line.indexOf(':')+1); line = line.trim();
// Because some tags have a trailing ":",
if (line.startsWith(":")) {
tag += ":";
line = line.substring(1);
}
// Indent lines starting by "at",
String indentation = "";
if (line.startsWith("at ")) {
indentation = " " + INDENTATION;
line = " " + INDENTATION + line;
}
// Print the prettified log,
Color color;
switch (logLevel) {
case "V": color = V_COLOR; break;
case "D": color = D_COLOR; break;
case "I": color = I_COLOR; break;
case "W": color = W_COLOR; break;
case "E": color = E_COLOR; break;
default:
color = Color.RESET;
}
String fields = adjustLength( date, DATE_LENGTH) + SEPARATOR +
adjustLength( time, TIME_LENGTH) + SEPARATOR +
adjustLength(processID, PROCESS_ID_LENGTH) + SEPARATOR +
adjustLength( threadID, THREAD_ID_LENGTH) + SEPARATOR +
adjustLength( logLevel, LOG_LEVEL_LENGTH) + SEPARATOR +
adjustLength( tag, TAG_LENGTH) + SEPARATOR;
// Split the message onto multiple lines if needed,
String message = chunkPreservingParentheses(line, MESSAGE_LENGTH, 2);
print(fields + message, color);
System.out.println();
while (line.length() > message.length()) {
// Debug,
//print(line, OTHER_COLOR);
//System.out.println("Line: " + line.length() + "length: " + message.length() + ", cont: " + CONTINUATION.length() + "dent: " + indentation.length());
//System.out.println();
// Remove the already printed part.
line = line.substring(message.length()-CONTINUATION.length());
// Add a dot to make links work,
boolean shouldAddDot=false;
if (line.matches("^[^\\.]*\\(.*:[123456789][1234567890]*\\).*")) shouldAddDot = true;
// Indent,
line = (shouldAddDot ? "." : (indentation.isEmpty() ? "" : " ")) + indentation + line;
// Take another chunk,
message = chunkPreservingParentheses(line, MESSAGE_LENGTH, 2+indentation.length());
// Front pad to align this part with the message body,
String paddedMessage = message;
for (int i=0; i<fields.length(); i++) paddedMessage = ' ' + paddedMessage;
// Print,
print(paddedMessage, color);
System.out.println();
}
return true; // Keep in local buffer.
}
private static String adjustLength(String text, int length) {
while (text.length() < length) text += ' ';
if (text.length() > length) {
text = text.substring(0, length-CONTINUATION.length());
text += CONTINUATION;
}
return text;
}
private static String chunkPreservingParentheses(String text, int length, int minChunckLength) {
if (text.length() <= length) return text;
// Take a chunk out of the text,
String chunk = text.substring(0, length-CONTINUATION.length()) + CONTINUATION;
// Check if a paranthesis was opened and not closed,
int lastOpenParanthesisIndex = chunk.lastIndexOf('(');
int lastCloseParanthesisIndex = chunk.lastIndexOf(')');
if (lastCloseParanthesisIndex <= lastOpenParanthesisIndex) { // Also works when either is not found.
if (minChunckLength<1) minChunckLength = 1;
if (lastOpenParanthesisIndex > minChunckLength+CONTINUATION.length()) { // Avoid endless loops.
int includeParenthesisSize = (CONTINUATION.length()>0) ? 1 : 0;
chunk = text.substring(0, lastOpenParanthesisIndex+includeParenthesisSize-CONTINUATION.length()) + CONTINUATION;
}
}
return chunk;
}
private static void repeatHistory() {
int index = currentLocationInHistory-historyLength;
if (index < 0) index += history.length;
for (int i=0; i<historyLength; i++) {
processLogcatLine(history[index]);
index = (index + 1) % history.length;
}
}
private static void print(String text, Color color) {
System.out.print(color);
System.out.print(text);
System.out.print(Color.RESET);
}
private static String removeRedundantSpaces(String text) {
String newText = text.replace(" ", " ");
while (!text.equals(newText)) {
text = newText;
newText = text.replace(" ", " ");
}
return text;
}
private static void clearAndroidStudioConsole() {
// Couldn't find a reliable way to clear Intellij terminal scrollback, so we just print
// a LOT of newlines,
StringBuilder bunchOfNewLines = new StringBuilder();
for (int i=0; i<124; i++) bunchOfNewLines.append(System.lineSeparator());
System.out.print(bunchOfNewLines);
// Scroll the current line to the top of the window,
try {
// If we are on Windows,
new ProcessBuilder("cmd", "/c", "cls").inheritIO().start().waitFor();
} catch (Exception e) {
// We are not on Windows,
bunchOfNewLines = new StringBuilder();
for (int i=0; i<124; i++) bunchOfNewLines.append("\b\r");
System.out.print(bunchOfNewLines);
}
}
private static void handleUserInput() {
// Line read. Unfortunately, java doesn't provide character by character reading out of the box.
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
String input = "";
do {
try {
if (bufferedReader.ready()) {
input = input = bufferedReader.readLine().toUpperCase();
// Set log level,
if (input.equals("V")||input.equals("D")||input.equals("I")||input.equals("W")||input.equals("E")) {
if (!logLevelToShow.equals(input)) {
logLevelToShow = input;
clearAndroidStudioConsole();
repeatHistory();
}
prettify("----- Log level set to " + logLevelToShow + " -----");
} else if (input.equals("C")) {
// Clear screen and history,
clearAndroidStudioConsole();
historyLength = 0;
}
} else {
Thread.sleep(100);
}
} catch (Exception e) { e.printStackTrace(); }
// Check if the logcat process is still alive,
if (!logcatProcess.isAlive()) {
prettify("----- adb logcat process terminated -----");
stopEverything = true;
}
} while (!stopEverything && !input.equals("Q"));
// Allow all monitoring threads to exit,
stopEverything = true;
}
interface ProcessListener {
void onNewLine(String line);
}
enum Color {
// Thanks to this answer: https://stackoverflow.com/a/51944613/1942069
//Color end string, color reset
RESET("\033[0m"),
// Regular Colors. Normal color, no bold, background color etc.
BLACK ("\033[0;30m"),
RED ("\033[0;31m"),
GREEN ("\033[0;32m"),
YELLOW ("\033[0;33m"),
BLUE ("\033[0;34m"),
MAGENTA("\033[0;35m"),
CYAN ("\033[0;36m"),
WHITE ("\033[0;37m"),
// Bold
BLACK_BOLD ("\033[1;30m"),
RED_BOLD ("\033[1;31m"),
GREEN_BOLD ("\033[1;32m"),
YELLOW_BOLD ("\033[1;33m"),
BLUE_BOLD ("\033[1;34m"),
MAGENTA_BOLD("\033[1;35m"),
CYAN_BOLD ("\033[1;36m"),
WHITE_BOLD ("\033[1;37m"),
// Underline
BLACK_UNDERLINED ("\033[4;30m"),
RED_UNDERLINED ("\033[4;31m"),
GREEN_UNDERLINED ("\033[4;32m"),
YELLOW_UNDERLINED ("\033[4;33m"),
BLUE_UNDERLINED ("\033[4;34m"),
MAGENTA_UNDERLINED("\033[4;35m"),
CYAN_UNDERLINED ("\033[4;36m"),
WHITE_UNDERLINED ("\033[4;37m"),
// Background
BLACK_BACKGROUND ("\033[40m"),
RED_BACKGROUND ("\033[41m"),
GREEN_BACKGROUND ("\033[42m"),
YELLOW_BACKGROUND ("\033[43m"),
BLUE_BACKGROUND ("\033[44m"),
MAGENTA_BACKGROUND("\033[45m"),
CYAN_BACKGROUND ("\033[46m"),
WHITE_BACKGROUND ("\033[47m"),
// High Intensity
BLACK_BRIGHT ("\033[0;90m"),
RED_BRIGHT ("\033[0;91m"),
GREEN_BRIGHT ("\033[0;92m"),
YELLOW_BRIGHT ("\033[0;93m"),
BLUE_BRIGHT ("\033[0;94m"),
MAGENTA_BRIGHT("\033[0;95m"),
CYAN_BRIGHT ("\033[0;96m"),
WHITE_BRIGHT ("\033[0;97m"),
// Bold High Intensity
BLACK_BOLD_BRIGHT ("\033[1;90m"),
RED_BOLD_BRIGHT ("\033[1;91m"),
GREEN_BOLD_BRIGHT ("\033[1;92m"),
YELLOW_BOLD_BRIGHT ("\033[1;93m"),
BLUE_BOLD_BRIGHT ("\033[1;94m"),
MAGENTA_BOLD_BRIGHT("\033[1;95m"),
CYAN_BOLD_BRIGHT ("\033[1;96m"),
WHITE_BOLD_BRIGHT ("\033[1;97m"),
// High Intensity backgrounds
BLACK_BACKGROUND_BRIGHT ("\033[0;100m"),
RED_BACKGROUND_BRIGHT ("\033[0;101m"),
GREEN_BACKGROUND_BRIGHT ("\033[0;102m"),
YELLOW_BACKGROUND_BRIGHT ("\033[0;103m"),
BLUE_BACKGROUND_BRIGHT ("\033[0;104m"),
MAGENTA_BACKGROUND_BRIGHT("\033[0;105m"),
CYAN_BACKGROUND_BRIGHT ("\033[0;106m"),
WHITE_BACKGROUND_BRIGHT ("\033[0;107m");
private final String code;
Color(String code) { this.code = code; }
@Override public String toString() { return code; }
}
}
只需将这段代码转储到Logcat.java并使用以下方法进行编译:
javac Logcat.java
并在Android Studio的嵌入式终端中运行:
java Logcat <your.package.name>
例如:
java Logcat com.nomone.vr_desktop
结果如下所示:
它是高度可定制的，我在应用程序的第一部分分离了大部分选项，所以你可以很容易地调整颜色和格式。如果adb工具不在PATH环境变量中，只需在编译前在ADB_FILE_PATH变量中设置它的完整路径(在代码中)。
当应用程序正在运行时，您可以键入以下快捷方式:
C清除屏幕和本地缓冲区。 V, i, d, w, e来改变logcat的级别。 优雅地退出。Ctrl+c也可以。
不幸的是，在按完这些键后，您必须按回车键。似乎Java不允许在不编写系统特定代码的情况下从控制台输入单个字符。对不起!
免责声明
如果使用adb连接多个设备，这将不起作用。 我还没有彻底测试这个。我只在少数设备上使用过一段时间。 我还没有在Windows或Mac上测试，但我尽量避免使用任何特定于系统的东西，所以它应该仍然有效。
我希望这能解决你的问题:)
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