对Gala的回答进行了详细分析，其中还将包括例外情况的原因：

private String extrapolateStackTrace(Exception ex) {
    Throwable e = ex;
    String trace = e.toString() + "\n";
    for (StackTraceElement e1 : e.getStackTrace()) {
        trace += "\t at " + e1.toString() + "\n";
    }
    while (e.getCause() != null) {
        e = e.getCause();
        trace += "Cause by: " + e.toString() + "\n";
        for (StackTraceElement e1 : e.getStackTrace()) {
            trace += "\t at " + e1.toString() + "\n";
        }
    }
    return trace;
}

Apache Commons Lang 3.4（JavaDoc）代码：

public static String getStackTrace(final Throwable throwable) {
    final StringWriter sw = new StringWriter();
    final PrintWriter pw = new PrintWriter(sw, true);
    throwable.printStackTrace(pw);
    return sw.getBuffer().toString();
}

与其他答案的不同之处在于，它在PrintWriter上使用autoFlush。

使用Throwable.printStackTrace（PrintWriter pw）将堆栈跟踪发送到适当的编写器。

import java.io.StringWriter;
import java.io.PrintWriter;

// ...

StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw);
e.printStackTrace(pw);
String sStackTrace = sw.toString(); // stack trace as a string
System.out.println(sStackTrace);

Kotlin>=1.4

在Throwable上使用内置函数stackTraceToString（）。

Kotlin<1.4

扩展Throwable类将提供String属性error.stackTraceString：

val Throwable.stackTraceString: String
  get() {
    val sw = StringWriter()
    val pw = PrintWriter(sw)
    this.printStackTrace(pw)
    return sw.toString()
  }

将堆栈跟踪打印到字符串

import java.io.PrintWriter;
import java.io.StringWriter;

public class StackTraceUtils {
    public static String stackTraceToString(StackTraceElement[] stackTrace) {
        StringWriter sw = new StringWriter();
        printStackTrace(stackTrace, new PrintWriter(sw));
        return sw.toString();
    }
    public static void printStackTrace(StackTraceElement[] stackTrace, PrintWriter pw) {
        for(StackTraceElement stackTraceEl : stackTrace) {
            pw.println(stackTraceEl);
        }
    }
}

当您想要打印当前线程堆栈跟踪而不创建Throwable实例时，这非常有用，但请注意，创建新的Throwable并从中获取堆栈跟踪实际上比调用thread.getStackTrace更快、更便宜。

没有java.io.*，它可以这样做。

String trace = e.toString() + "\n";                     

for (StackTraceElement e1 : e.getStackTrace()) {
    trace += "\t at " + e1.toString() + "\n";
}   

然后跟踪变量保存堆栈跟踪。输出也包含初始原因，输出与printStackTrace（）相同

例如，printStackTrace（）产生：

java.io.FileNotFoundException: / (Is a directory)
    at java.io.FileOutputStream.open0(Native Method)
    at java.io.FileOutputStream.open(FileOutputStream.java:270)
    at java.io.FileOutputStream.<init>(FileOutputStream.java:213)
    at java.io.FileOutputStream.<init>(FileOutputStream.java:101)
    at Test.main(Test.java:9)

当打印到stdout时，跟踪字符串保持

java.io.FileNotFoundException: / (Is a directory)
     at java.io.FileOutputStream.open0(Native Method)
     at java.io.FileOutputStream.open(FileOutputStream.java:270)
     at java.io.FileOutputStream.<init>(FileOutputStream.java:213)
     at java.io.FileOutputStream.<init>(FileOutputStream.java:101)
     at Test.main(Test.java:9)